Don't use SkipLocalsInit

Add test and probable fix for Issue 617

.github/workflows/dotnetcore.yml

@@ -12,13 +12,9 @@ jobs:
     - uses: actions/checkout@v1
     - uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 5.0.101
+        dotnet-version: 5.0.401
     - run: dotnet run -p build/build.csproj
     - uses: actions/upload-artifact@v2
       with:
         name: ${{ matrix.os }}-sharpcompress.nupkg
         path: artifacts/*
-    - uses: actions/upload-artifact@v2
-      with:
-        name: ${{ matrix.os }}-sharpcompress.snupkg
-        path: artifacts/*

build/Program.cs

@@ -49,20 +49,20 @@ class Program
         Target(Build, DependsOn(Format),
                framework =>
                {
-                   if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && framework == "net46")
-                   {
-                       return;
-                   }
                    Run("dotnet", "build src/SharpCompress/SharpCompress.csproj -c Release");
                });
 
-        Target(Test, DependsOn(Build), ForEach("net5.0"),
+        Target(Test, DependsOn(Build), ForEach("net5.0", "net461"),
                framework =>
                {
                    IEnumerable<string> GetFiles(string d)
                    {
                        return Glob.Files(".", d);
                    }
+                   if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && framework == "net461")
+                   {
+                       return;
+                   }
 
                    foreach (var file in GetFiles("**/*.Test.csproj"))
                    {

build/build.csproj

@@ -6,9 +6,9 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Bullseye" Version="3.6.0" />
+    <PackageReference Include="Bullseye" Version="3.8.0" />
     <PackageReference Include="Glob" Version="1.1.8" />
-    <PackageReference Include="SimpleExec" Version="6.4.0" />
+    <PackageReference Include="SimpleExec" Version="8.0.0" />
   </ItemGroup>
 
 </Project>

global.json

@@ -1,5 +1,6 @@
 {
   "sdk": {
-    "version": "5.0.101"
+    "version": "5.0.300",
+    "rollForward": "latestFeature"
   }
 }

src/SharpCompress/Algorithms/Alder32.cs

@@ -4,7 +4,7 @@
 using System;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
-#if !NETSTANDARD2_0 && !NETSTANDARD2_1
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
 using System.Runtime.Intrinsics;
 using System.Runtime.Intrinsics.X86;
 #endif
@@ -22,7 +22,7 @@ namespace SharpCompress.Algorithms
         /// </summary>
         public const uint SeedValue = 1U;
 
-#if !NETSTANDARD2_0 && !NETSTANDARD2_1
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
         private const int MinBufferSize = 64;
 #endif
 
@@ -51,12 +51,7 @@ namespace SharpCompress.Algorithms
         /// <returns>The <see cref="uint"/>.</returns>
         public static uint Calculate(uint adler, ReadOnlySpan<byte> buffer)
         {
-            if (buffer.IsEmpty)
-            {
-                return SeedValue;
-            }
-
-#if !NETSTANDARD2_0 && !NETSTANDARD2_1
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
             if (Sse3.IsSupported && buffer.Length >= MinBufferSize)
             {
                 return CalculateSse(adler, buffer);
@@ -69,7 +64,7 @@ namespace SharpCompress.Algorithms
         }
 
         // Based on https://github.com/chromium/chromium/blob/master/third_party/zlib/adler32_simd.c
-#if !NETSTANDARD2_0 && !NETSTANDARD2_1
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
         private static unsafe uint CalculateSse(uint adler, ReadOnlySpan<byte> buffer)
         {
             uint s1 = adler & 0xFFFF;
@@ -282,4 +277,4 @@ namespace SharpCompress.Algorithms
             return (s2 << 16) | s1;
         }
     }
-}
+}

src/SharpCompress/Archives/ArchiveFactory.cs

@@ -1,6 +1,5 @@
 using System;
 using System.IO;
-using SharpCompress.Archives.Dmg;
 using SharpCompress.Archives.GZip;
 using SharpCompress.Archives.Rar;
 using SharpCompress.Archives.SevenZip;
@@ -45,12 +44,6 @@ namespace SharpCompress.Archives
                 return GZipArchive.Open(stream, readerOptions);
             }
             stream.Seek(0, SeekOrigin.Begin);
-            if (DmgArchive.IsDmgFile(stream))
-            {
-                stream.Seek(0, SeekOrigin.Begin);
-                return DmgArchive.Open(stream, readerOptions);
-            }
-            stream.Seek(0, SeekOrigin.Begin);
             if (RarArchive.IsRarFile(stream, readerOptions))
             {
                 stream.Seek(0, SeekOrigin.Begin);
@@ -62,7 +55,7 @@ namespace SharpCompress.Archives
                 stream.Seek(0, SeekOrigin.Begin);
                 return TarArchive.Open(stream, readerOptions);
             }
-            throw new InvalidOperationException("Cannot determine compressed stream type. Supported Archive Formats: Zip, GZip, Tar, Rar, 7Zip, LZip, Dmg");
+            throw new InvalidOperationException("Cannot determine compressed stream type. Supported Archive Formats: Zip, GZip, Tar, Rar, 7Zip, LZip");
         }
 
         public static IWritableArchive Create(ArchiveType type)
@@ -113,12 +106,6 @@ namespace SharpCompress.Archives
                 return GZipArchive.Open(fileInfo, options);
             }
             stream.Seek(0, SeekOrigin.Begin);
-            if (DmgArchive.IsDmgFile(stream))
-            {
-                stream.Seek(0, SeekOrigin.Begin);
-                return DmgArchive.Open(fileInfo, options);
-            }
-            stream.Seek(0, SeekOrigin.Begin);
             if (RarArchive.IsRarFile(stream, options))
             {
                 return RarArchive.Open(fileInfo, options);
@@ -128,7 +115,7 @@ namespace SharpCompress.Archives
             {
                 return TarArchive.Open(fileInfo, options);
             }
-            throw new InvalidOperationException("Cannot determine compressed stream type. Supported Archive Formats: Zip, GZip, Tar, Rar, 7Zip, Dmg");
+            throw new InvalidOperationException("Cannot determine compressed stream type. Supported Archive Formats: Zip, GZip, Tar, Rar, 7Zip");
         }
 
         /// <summary>

src/SharpCompress/Archives/Dmg/DmgArchive.cs

@@ -1,117 +0,0 @@
-using SharpCompress.Common;
-using SharpCompress.Common.Dmg;
-using SharpCompress.Common.Dmg.Headers;
-using SharpCompress.Common.Dmg.HFS;
-using SharpCompress.Readers;
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-
-namespace SharpCompress.Archives.Dmg
-{
-    public class DmgArchive : AbstractArchive<DmgArchiveEntry, DmgVolume>
-    {
-        private readonly string _fileName;
-
-        internal DmgArchive(FileInfo fileInfo, ReaderOptions readerOptions)
-            : base(ArchiveType.Dmg, fileInfo, readerOptions)
-        {
-            _fileName = fileInfo.FullName;
-        }
-
-        internal DmgArchive(Stream stream, ReaderOptions readerOptions)
-            : base(ArchiveType.Dmg, stream.AsEnumerable(), readerOptions)
-        {
-            _fileName = string.Empty;
-        }
-
-        protected override IReader CreateReaderForSolidExtraction()
-            => new DmgReader(ReaderOptions, this, _fileName);
-
-        protected override IEnumerable<DmgArchiveEntry> LoadEntries(IEnumerable<DmgVolume> volumes)
-            => volumes.Single().LoadEntries();
-
-        protected override IEnumerable<DmgVolume> LoadVolumes(FileInfo file)
-            => new DmgVolume(this, file.OpenRead(), file.FullName, ReaderOptions).AsEnumerable();
-
-        protected override IEnumerable<DmgVolume> LoadVolumes(IEnumerable<Stream> streams)
-            => new DmgVolume(this, streams.Single(), string.Empty, ReaderOptions).AsEnumerable();
-
-        public static bool IsDmgFile(FileInfo fileInfo)
-        {
-            if (!fileInfo.Exists) return false;
-
-            using var stream = fileInfo.OpenRead();
-            return IsDmgFile(stream);
-        }
-
-        public static bool IsDmgFile(Stream stream)
-        {
-            long headerPos = stream.Length - DmgHeader.HeaderSize;
-            if (headerPos < 0) return false;
-            stream.Position = headerPos;
-
-            return DmgHeader.TryRead(stream, out _);
-        }
-
-        /// <summary>
-        /// Constructor expects a filepath to an existing file.
-        /// </summary>
-        /// <param name="filePath"></param>
-        /// <param name="readerOptions"></param>
-        public static DmgArchive Open(string filePath, ReaderOptions? readerOptions = null)
-        {
-            filePath.CheckNotNullOrEmpty(nameof(filePath));
-            return Open(new FileInfo(filePath), readerOptions ?? new ReaderOptions());
-        }
-
-        /// <summary>
-        /// Constructor with a FileInfo object to an existing file.
-        /// </summary>
-        /// <param name="fileInfo"></param>
-        /// <param name="readerOptions"></param>
-        public static DmgArchive Open(FileInfo fileInfo, ReaderOptions? readerOptions = null)
-        {
-            fileInfo.CheckNotNull(nameof(fileInfo));
-            return new DmgArchive(fileInfo, readerOptions ?? new ReaderOptions());
-        }
-
-        /// <summary>
-        /// Takes a seekable Stream as a source
-        /// </summary>
-        /// <param name="stream"></param>
-        /// <param name="readerOptions"></param>
-        public static DmgArchive Open(Stream stream, ReaderOptions? readerOptions = null)
-        {
-            stream.CheckNotNull(nameof(stream));
-            return new DmgArchive(stream, readerOptions ?? new ReaderOptions());
-        }
-
-        private sealed class DmgReader : AbstractReader<DmgEntry, DmgVolume>
-        {
-            private readonly DmgArchive _archive;
-            private readonly string _fileName;
-            private readonly Stream? _partitionStream;
-
-            public override DmgVolume Volume { get; }
-
-            internal DmgReader(ReaderOptions readerOptions, DmgArchive archive, string fileName)
-                : base(readerOptions, ArchiveType.Dmg)
-            {
-                _archive = archive;
-                _fileName = fileName;
-                Volume = archive.Volumes.Single();
-
-                using var compressedStream = DmgUtil.LoadHFSPartitionStream(Volume.Stream, Volume.Header);
-                _partitionStream = compressedStream?.Decompress();
-            }
-
-            protected override IEnumerable<DmgEntry> GetEntries(Stream stream)
-            {
-                if (_partitionStream is null) return Array.Empty<DmgArchiveEntry>();
-                else return HFSUtil.LoadEntriesFromPartition(_partitionStream, _fileName, _archive);
-            }
-        }
-    }
-}

src/SharpCompress/Archives/Dmg/DmgArchiveEntry.cs

@@ -1,32 +0,0 @@
-using SharpCompress.Common.Dmg;
-using SharpCompress.Common.Dmg.HFS;
-using System;
-using System.IO;
-
-namespace SharpCompress.Archives.Dmg
-{
-    public sealed class DmgArchiveEntry : DmgEntry, IArchiveEntry
-    {
-        private readonly Stream? _stream;
-
-        public bool IsComplete { get; } = true;
-
-        public IArchive Archive { get; }
-
-        internal DmgArchiveEntry(Stream? stream, DmgArchive archive, HFSCatalogRecord record, string path, DmgFilePart part)
-            : base(record, path, stream?.Length ?? 0, part)
-        {
-            _stream = stream;
-            Archive = archive;
-        }
-
-        public Stream OpenEntryStream()
-        {
-            if (IsDirectory)
-                throw new NotSupportedException("Directories cannot be opened as stream");
-
-            _stream!.Position = 0;
-            return _stream;
-        }
-    }
-}

src/SharpCompress/Archives/Rar/RarArchive.cs

@@ -10,7 +10,7 @@ using SharpCompress.Readers.Rar;
 
 namespace SharpCompress.Archives.Rar
 {
-    public class 
+    public class
         RarArchive : AbstractArchive<RarArchiveEntry, RarVolume>
     {
         internal Lazy<IRarUnpack> UnpackV2017 { get; } = new Lazy<IRarUnpack>(() => new SharpCompress.Compressors.Rar.UnpackV2017.Unpack());

src/SharpCompress/AssemblyInfo.cs

@@ -5,7 +5,7 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyTitle("SharpCompress")]
 [assembly: AssemblyProduct("SharpCompress")]
 [assembly: InternalsVisibleTo("SharpCompress.Test" + SharpCompress.AssemblyInfo.PublicKeySuffix)]
-[assembly: CLSCompliant(true)]
+[assembly: CLSCompliant(false)]
 
 namespace SharpCompress
 {

src/SharpCompress/Common/ArchiveEncoding.cs

@@ -36,7 +36,7 @@ namespace SharpCompress.Common
             Password = password;
         }
 
-#if !NET461
+#if !NETFRAMEWORK
         static ArchiveEncoding()
         {
             Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);

src/SharpCompress/Common/ArchiveException.cs

@@ -8,10 +8,5 @@ namespace SharpCompress.Common
             : base(message)
         {
         }
-
-        public ArchiveException(string message, Exception inner)
-            : base(message, inner)
-        {
-        }
     }
 }

src/SharpCompress/Common/ArchiveType.cs

@@ -7,6 +7,6 @@
         Tar,
         SevenZip,
         GZip,
-        Dmg
+        ZStandard
     }
 }

src/SharpCompress/Common/CompressionType.cs

@@ -14,6 +14,7 @@
         LZip,
         Xz,
         Unknown,
-        Deflate64
+        Deflate64,
+        ZStandard,
     }
 }

src/SharpCompress/Common/Dmg/DmgBlockDataStream.cs

@@ -1,323 +0,0 @@
-using SharpCompress.Common.Dmg.Headers;
-using SharpCompress.Compressors;
-using SharpCompress.Compressors.ADC;
-using SharpCompress.Compressors.BZip2;
-using SharpCompress.Compressors.Deflate;
-using SharpCompress.IO;
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Threading.Tasks;
-
-namespace SharpCompress.Common.Dmg
-{
-    internal sealed class DmgBlockDataStream : Stream
-    {
-        private readonly Stream _baseStream;
-        private readonly DmgHeader _header;
-        private readonly BlkxTable _table;
-        private long _position;
-        private bool _isEnded;
-        private int _chunkIndex;
-        private Stream? _chunkStream;
-        private long _chunkPos;
-        
-        public override bool CanRead => true;
-        public override bool CanWrite => false;
-        public override bool CanSeek => true;
-        public override long Length { get; }
-
-        public override long Position
-        {
-            get => _position;
-            set
-            {
-                if ((value < 0) || (value > Length)) throw new ArgumentOutOfRangeException(nameof(value));
-
-                if (value == Length)
-                {
-                    // End of the stream
-
-                    _position = Length;
-                    _isEnded = true;
-                    _chunkIndex = -1;
-                    _chunkStream = null;
-                }
-                else if (value != _position)
-                {
-                    _position = value;
-
-                    // We can only seek over entire chunks at a time because some chunks may be compressed.
-                    // So we first find the chunk that we are now in, then we read to the exact position inside that chunk.
-
-                    for (int i = 0; i < _table.Chunks.Count; i++)
-                    {
-                        var chunk = _table.Chunks[i];
-                        if (IsChunkValid(chunk) && (chunk.UncompressedOffset <= (ulong)_position)
-                            && ((chunk.UncompressedOffset + chunk.UncompressedLength) > (ulong)_position))
-                        {
-                            if (i == _chunkIndex)
-                            {
-                                // We are still in the same chunk, so if the new position is
-                                // behind the previous one we can just read to the new position.
-
-                                long offset = (long)chunk.UncompressedOffset + _chunkPos;
-                                if (offset <= _position)
-                                {
-                                    long skip = _position - offset;
-                                    _chunkStream!.Skip(skip);
-                                    _chunkPos += skip;
-                                    break;
-                                }
-                            }
-
-                            _chunkIndex = i;
-                            _chunkStream = GetChunkStream();
-                            _chunkPos = 0;
-
-                            // If the chunk happens to not be compressed this read will still result in a fast seek
-                            if ((ulong)_position != chunk.UncompressedOffset)
-                            {
-                                long skip = _position - (long)chunk.UncompressedOffset;
-                                _chunkStream.Skip(skip);
-                                _chunkPos = skip;
-                            }
-
-                            break;
-                        }
-                    }
-                }
-            }
-        }
-
-        public DmgBlockDataStream(Stream baseStream, DmgHeader header, BlkxTable table)
-        {
-            if (!baseStream.CanRead) throw new ArgumentException("Requires a readable stream", nameof(baseStream));
-            if (!baseStream.CanSeek) throw new ArgumentException("Requires a seekable stream", nameof(baseStream));
-
-            _baseStream = baseStream;
-            _header = header;
-            _table = table;
-
-            Length = 0;
-            foreach (var chunk in table.Chunks)
-            {
-                if (IsChunkValid(chunk))
-                    Length += (long)chunk.UncompressedLength;
-            }
-
-            _position = 0;
-            _chunkIndex = -1;
-            _chunkIndex = GetNextChunk();
-            _isEnded = _chunkIndex < 0;
-            if (!_isEnded) _chunkStream = GetChunkStream();
-            _chunkPos = 0;
-        }
-
-        private static bool IsChunkValid(BlkxChunk chunk)
-        {
-            return chunk.Type switch
-            {
-                BlkxChunkType.Zero => true,
-                BlkxChunkType.Uncompressed => true,
-                BlkxChunkType.Ignore => true,
-                BlkxChunkType.AdcCompressed => true,
-                BlkxChunkType.ZlibCompressed => true,
-                BlkxChunkType.Bz2Compressed => true,
-                _ => false
-            };
-        }
-
-        private int GetNextChunk()
-        {
-            int index = _chunkIndex;
-            bool isValid = false;
-            while (!isValid)
-            {
-                index++;
-                if (index >= _table.Chunks.Count) return -1;
-
-                var chunk = _table.Chunks[index];
-                if (chunk.Type == BlkxChunkType.Last) return -1;
-
-                isValid = IsChunkValid(chunk);
-            }
-            return index;
-        }
-
-        private Stream GetChunkStream()
-        {
-            if (_chunkIndex < 0)
-                throw new InvalidOperationException("Invalid chunk index");
-
-            var chunk = _table.Chunks[_chunkIndex];
-
-            // For our purposes, ignore behaves the same as zero
-            if ((chunk.Type == BlkxChunkType.Zero) || (chunk.Type == BlkxChunkType.Ignore))
-                return new ConstantStream(0, (long)chunk.UncompressedLength);
-
-            // We first create a sub-stream on the region of the base stream where the
-            // (possibly compressed) data is physically located at.
-            var subStream = new SeekableSubStream(_baseStream,
-                (long)(_header.DataForkOffset + _table.DataOffset + chunk.CompressedOffset),
-                (long)chunk.CompressedLength);
-
-            // Then we nest that sub-stream into the apropriate compressed stream.
-            return chunk.Type switch
-            {
-                BlkxChunkType.Uncompressed => subStream,
-                BlkxChunkType.AdcCompressed => new ADCStream(subStream, CompressionMode.Decompress),
-                BlkxChunkType.ZlibCompressed => new ZlibStream(subStream, CompressionMode.Decompress),
-                BlkxChunkType.Bz2Compressed => new BZip2Stream(subStream, CompressionMode.Decompress, false),
-                _ => throw new InvalidOperationException("Invalid chunk type")
-            };
-        }
-
-        // Decompresses the entire stream in memory for faster extraction.
-        // This is about two orders of magnitude faster than decompressing
-        // on-the-fly while extracting, but also eats RAM for breakfest.
-        public Stream Decompress()
-        {
-            // We have to load all the chunks into separate memory streams first
-            // because otherwise the decompression threads would block each other
-            // and actually be slower than just a single decompression thread.
-
-            var rawStreams = new Stream?[_table.Chunks.Count];
-            for (int i = 0; i < rawStreams.Length; i++)
-            {
-                var chunk = _table.Chunks[i];
-                if (IsChunkValid(chunk))
-                {
-                    if ((chunk.Type == BlkxChunkType.Zero) || (chunk.Type == BlkxChunkType.Ignore))
-                    {
-                        rawStreams[i] = new ConstantStream(0, (long)chunk.UncompressedLength);
-                    }
-                    else
-                    {
-                        var subStream = new SeekableSubStream(_baseStream,
-                        (long)(_header.DataForkOffset + _table.DataOffset + chunk.CompressedOffset),
-                        (long)chunk.CompressedLength);
-
-                        var memStream = new MemoryStream();
-                        subStream.CopyTo(memStream);
-                        memStream.Position = 0;
-                        rawStreams[i] = memStream;
-                    }
-                }
-                else
-                {
-                    rawStreams[i] = null;
-                }
-            }
-
-            // Now we can decompress the chunks multithreaded
-
-            var streams = new Stream?[_table.Chunks.Count];
-            Parallel.For(0, streams.Length, i =>
-            {
-                var rawStream = rawStreams[i];
-                if (rawStream is not null)
-                {
-                    var chunk = _table.Chunks[i];
-                    if ((chunk.Type == BlkxChunkType.Zero)
-                     || (chunk.Type == BlkxChunkType.Ignore)
-                     || (chunk.Type == BlkxChunkType.Uncompressed))
-                    {
-                        streams[i] = rawStream;
-                    }
-                    else
-                    {
-                        Stream compStream = chunk.Type switch
-                        {
-                            BlkxChunkType.AdcCompressed => new ADCStream(rawStream, CompressionMode.Decompress),
-                            BlkxChunkType.ZlibCompressed => new ZlibStream(rawStream, CompressionMode.Decompress),
-                            BlkxChunkType.Bz2Compressed => new BZip2Stream(rawStream, CompressionMode.Decompress, false),
-                            _ => throw new InvalidOperationException("Invalid chunk type")
-                        };
-
-                        var memStream = new MemoryStream();
-                        compStream.CopyTo(memStream);
-                        compStream.Dispose();
-
-                        memStream.Position = 0;
-                        streams[i] = memStream;
-                    }
-
-                    rawStream.Dispose();
-                    rawStreams[i] = null;
-                }
-                else
-                {
-                    streams[i] = null;
-                }
-            });
-
-            return new CompositeStream((IEnumerable<Stream>)streams.Where(s => s is not null));
-        }
-
-        public override int Read(byte[] buffer, int offset, int count)
-        {
-            if (_isEnded) return 0;
-
-            int readCount = _chunkStream!.Read(buffer, offset, count);
-            _chunkPos += readCount;
-
-            while (readCount < count)
-            {
-                // Current chunk has ended, so we have to continue reading from the next chunk.
-
-                _chunkIndex = GetNextChunk();
-                if (_chunkIndex < 0)
-                {
-                    // We have reached the last chunk
-
-                    _isEnded = true;
-                    _chunkPos = 0;
-                    _position += readCount;
-                    return readCount;
-                }
-
-                _chunkStream = GetChunkStream();
-                int rc = _chunkStream.Read(buffer, offset + readCount, count - readCount);
-                _chunkPos = rc;
-                readCount += rc;
-            }
-
-            _position += readCount;
-            return readCount;
-        }
-
-        public override void Flush()
-        { }
-
-        public override long Seek(long offset, SeekOrigin origin)
-        {
-            switch (origin)
-            {
-                case SeekOrigin.Begin:
-                    Position = offset;
-                    break;
-
-                case SeekOrigin.Current:
-                    Position += offset;
-                    break;
-
-                case SeekOrigin.End:
-                    Position = Length - offset;
-                    break;
-            }
-
-            return Position;
-        }
-
-        public override void SetLength(long value)
-            => throw new NotSupportedException();
-
-        public override void Write(byte[] buffer, int offset, int count)
-            => throw new NotSupportedException();
-
-        protected override void Dispose(bool disposing)
-        { }
-    }
-}

src/SharpCompress/Common/Dmg/DmgEntry.cs

@@ -1,52 +0,0 @@
-using SharpCompress.Common.Dmg.HFS;
-using System;
-using System.Collections.Generic;
-
-namespace SharpCompress.Common.Dmg
-{
-    public abstract class DmgEntry : Entry
-    {
-        public override string Key { get; }
-        public override bool IsDirectory { get; }
-        public override long Size { get; }
-        public override long CompressedSize { get; }
-        public override CompressionType CompressionType { get; }
-        public override DateTime? LastModifiedTime { get; }
-        public override DateTime? CreatedTime { get; }
-        public override DateTime? LastAccessedTime { get; }
-        public override DateTime? ArchivedTime { get; }
-        
-        public override long Crc { get; } = 0; // Not stored
-        public override string? LinkTarget { get; } = null;
-        public override bool IsEncrypted { get; } = false;
-        public override bool IsSplitAfter { get; } = false;
-
-        internal override IEnumerable<FilePart> Parts { get; }
-
-        internal DmgEntry(HFSCatalogRecord record, string path, long size, DmgFilePart part)
-        {
-            Key = path;
-            IsDirectory = record.Type == HFSCatalogRecordType.Folder;
-            Size = CompressedSize = size;              // There is no way to get the actual compressed size or the compression type of
-            CompressionType = CompressionType.Unknown; // a file in a DMG archive since the files are nested inside the HFS partition.
-            Parts = part.AsEnumerable();
-
-            if (IsDirectory)
-            {
-                var folder = (HFSCatalogFolder)record;
-                LastModifiedTime = (folder.AttributeModDate > folder.ContentModDate) ? folder.AttributeModDate : folder.ContentModDate;
-                CreatedTime = folder.CreateDate;
-                LastAccessedTime = folder.AccessDate;
-                ArchivedTime = folder.BackupDate;
-            }
-            else
-            {
-                var file = (HFSCatalogFile)record;
-                LastModifiedTime = (file.AttributeModDate > file.ContentModDate) ? file.AttributeModDate : file.ContentModDate;
-                CreatedTime = file.CreateDate;
-                LastAccessedTime = file.AccessDate;
-                ArchivedTime = file.BackupDate;
-            }
-        }
-    }
-}

src/SharpCompress/Common/Dmg/DmgFilePart.cs

@@ -1,21 +0,0 @@
-using System.IO;
-
-namespace SharpCompress.Common.Dmg
-{
-    internal sealed class DmgFilePart : FilePart
-    {
-        private readonly Stream _stream;
-
-        internal override string FilePartName { get; }
-
-        public DmgFilePart(Stream stream, string fileName)
-            : base(new ArchiveEncoding())
-        {
-            _stream = stream;
-            FilePartName = fileName;
-        }
-
-        internal override Stream GetCompressedStream() => _stream;
-        internal override Stream? GetRawStream() => null;
-    }
-}

src/SharpCompress/Common/Dmg/DmgUtil.cs

@@ -1,183 +0,0 @@
-using SharpCompress.Common.Dmg.Headers;
-using System;
-using System.Collections.Generic;
-using System.Globalization;
-using System.IO;
-using System.Text;
-using System.Xml.Linq;
-
-namespace SharpCompress.Common.Dmg
-{
-    internal static class DmgUtil
-    {
-        private const string MalformedXmlMessage = "Malformed XML block";
-
-        private static T[] ParseArray<T>(in XElement parent, in Func<XElement, T> parseElement)
-        {
-            var list = new List<T>();
-
-            foreach (var node in parent.Elements())
-                list.Add(parseElement(node));
-
-            return list.ToArray();
-        }
-
-        private static Dictionary<string, T> ParseDict<T>(in XElement parent, in Func<XElement, T> parseValue)
-        {
-            var dict = new Dictionary<string, T>();
-
-            string? key = null;
-            foreach (var node in parent.Elements())
-            {
-                if (string.Equals(node.Name.LocalName, "key", StringComparison.Ordinal))
-                {
-                    key = node.Value;
-                }
-                else if (key is not null)
-                {
-                    var value = parseValue(node);
-                    dict.Add(key, value);
-                    key = null;
-                }
-            }
-
-            return dict;
-        }
-
-        private static Dictionary<string, Dictionary<string, Dictionary<string, string>[]>> ParsePList(in XDocument doc)
-        {
-            var dictNode = doc.Root?.Element("dict");
-            if (dictNode is null) throw new InvalidFormatException(MalformedXmlMessage);
-
-            static Dictionary<string, string> ParseObject(XElement parent)
-                => ParseDict(parent, node => node.Value);
-
-            static Dictionary<string, string>[] ParseObjectArray(XElement parent)
-                => ParseArray(parent, ParseObject);
-
-            static Dictionary<string, Dictionary<string, string>[]> ParseSubDict(XElement parent)
-                => ParseDict(parent, ParseObjectArray);
-
-            return ParseDict(dictNode, ParseSubDict);
-        }
-
-        private static BlkxData CreateDataFromDict(in Dictionary<string, string> dict)
-        {
-            static bool TryParseHex(string? s, out uint value)
-            {
-                value = 0;
-                if (string.IsNullOrEmpty(s)) return false;
-
-                if (s!.StartsWith("0x", StringComparison.OrdinalIgnoreCase))
-                    s = s.Substring(2);
-
-                return uint.TryParse(s, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out value);
-            }
-
-            if (!dict.TryGetValue("ID", out string? idStr) || !int.TryParse(idStr, out int id))
-                throw new InvalidFormatException(MalformedXmlMessage);
-            if (!dict.TryGetValue("Name", out string? name))
-                throw new InvalidFormatException(MalformedXmlMessage);
-            if (!dict.TryGetValue("Attributes", out string? attribStr) || !TryParseHex(attribStr, out uint attribs))
-                throw new InvalidFormatException(MalformedXmlMessage);
-            if (!dict.TryGetValue("Data", out string? base64Data) || string.IsNullOrEmpty(base64Data))
-                throw new InvalidFormatException(MalformedXmlMessage);
-
-            try
-            {
-                var data = Convert.FromBase64String(base64Data);
-                if (!BlkxTable.TryRead(data, out var table))
-                    throw new InvalidFormatException("Invalid BLKX table");
-
-                return new BlkxData(id, name, attribs, table!);
-            }
-            catch (FormatException ex)
-            {
-                throw new InvalidFormatException(MalformedXmlMessage, ex);
-            }
-        }
-
-        public static DmgBlockDataStream? LoadHFSPartitionStream(Stream baseStream, DmgHeader header)
-        {
-            if ((header.XMLOffset + header.XMLLength) >= (ulong)baseStream.Length)
-                throw new IncompleteArchiveException("XML block incomplete");
-            if ((header.DataForkOffset + header.DataForkLength) >= (ulong)baseStream.Length)
-                throw new IncompleteArchiveException("Data block incomplete");
-
-            baseStream.Position = (long)header.XMLOffset;
-            var xmlBuffer = new byte[header.XMLLength];
-            baseStream.Read(xmlBuffer, 0, (int)header.XMLLength);
-            var xml = Encoding.ASCII.GetString(xmlBuffer);
-
-            var doc = XDocument.Parse(xml);
-            var pList = ParsePList(doc);
-            if (!pList.TryGetValue("resource-fork", out var resDict) || !resDict.TryGetValue("blkx", out var blkxDicts))
-                throw new InvalidFormatException(MalformedXmlMessage);
-
-            var objs = new BlkxData[blkxDicts.Length];
-            for (int i = 0; i < objs.Length; i++)
-                objs[i] = CreateDataFromDict(blkxDicts[i]);
-
-            // Index 0 is the protective MBR partition
-            // Index 1 is the GPT header
-            // Index 2 is the GPT partition table
-
-            try
-            {
-                var headerData = objs[1];
-                using var headerStream = new DmgBlockDataStream(baseStream, header, headerData.Table);
-                if (!GptHeader.TryRead(headerStream, out var gptHeader))
-                    throw new InvalidFormatException("Invalid GPT header");
-
-                var tableData = objs[2];
-                using var tableStream = new DmgBlockDataStream(baseStream, header, tableData.Table);
-                var gptTable = new GptPartitionEntry[gptHeader!.EntriesCount];
-                for (int i = 0; i < gptHeader.EntriesCount; i++)
-                    gptTable[i] = GptPartitionEntry.Read(tableStream);
-
-                foreach (var entry in gptTable)
-                {
-                    if (entry.TypeGuid == PartitionFormat.AppleHFS)
-                    {
-                        BlkxData? partitionData = null;
-                        for (int i = 3; i < objs.Length; i++)
-                        {
-                            if (objs[i].Name.StartsWith(entry.Name, StringComparison.Ordinal))
-                            {
-                                partitionData = objs[i];
-                                break;
-                            }
-                        }
-
-                        if (partitionData is null)
-                            throw new InvalidFormatException($"Missing partition {entry.Name}");
-
-                        return new DmgBlockDataStream(baseStream, header, partitionData.Table);
-                    }
-                }
-
-                return null;
-            }
-            catch (EndOfStreamException ex)
-            {
-                throw new IncompleteArchiveException("Partition incomplete", ex);
-            }
-        }
-
-        private sealed class BlkxData
-        {
-            public int Id { get; }
-            public string Name { get; }
-            public uint Attributes { get; }
-            public BlkxTable Table { get; }
-
-            public BlkxData(int id, string name, uint attributes, BlkxTable table)
-            {
-                Id = id;
-                Name = name;
-                Attributes = attributes;
-                Table = table;
-            }
-        }
-    }
-}

src/SharpCompress/Common/Dmg/DmgVolume.cs

@@ -1,38 +0,0 @@
-using SharpCompress.Archives.Dmg;
-using SharpCompress.Common.Dmg.Headers;
-using SharpCompress.Common.Dmg.HFS;
-using System;
-using System.Collections.Generic;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg
-{
-    public class DmgVolume : Volume
-    {
-        private readonly DmgArchive _archive;
-        private readonly string _fileName;
-
-        internal DmgHeader Header { get; }
-
-        public DmgVolume(DmgArchive archive, Stream stream, string fileName, Readers.ReaderOptions readerOptions)
-            : base(stream, readerOptions)
-        {
-            _archive = archive;
-            _fileName = fileName;
-
-            long pos = stream.Length - DmgHeader.HeaderSize;
-            if (pos < 0) throw new InvalidFormatException("Invalid DMG volume");
-            stream.Position = pos;
-
-            if (DmgHeader.TryRead(stream, out var header)) Header = header!;
-            else throw new InvalidFormatException("Invalid DMG volume");
-        }
-
-        internal IEnumerable<DmgArchiveEntry> LoadEntries()
-        {
-            var partitionStream = DmgUtil.LoadHFSPartitionStream(Stream, Header);
-            if (partitionStream is null) return Array.Empty<DmgArchiveEntry>();
-            else return HFSUtil.LoadEntriesFromPartition(partitionStream, _fileName, _archive);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSCatalogRecord.cs

@@ -1,336 +0,0 @@
-using System;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal sealed class HFSCatalogKey : HFSStructBase, IEquatable<HFSCatalogKey>, IComparable<HFSCatalogKey>, IComparable
-    {
-        private readonly StringComparer _comparer;
-
-        public uint ParentId { get; }
-
-        public string Name { get; }
-
-        private static StringComparer GetComparer(HFSKeyCompareType compareType, bool isHFSX)
-        {
-            if (isHFSX)
-            {
-                return compareType switch
-                {
-                    HFSKeyCompareType.CaseFolding => StringComparer.InvariantCultureIgnoreCase,
-                    HFSKeyCompareType.BinaryCompare => StringComparer.Ordinal,
-                    _ => StringComparer.InvariantCultureIgnoreCase
-                };
-            }
-            else
-            {
-                return StringComparer.InvariantCultureIgnoreCase;
-            }
-        }
-
-        public HFSCatalogKey(uint parentId, string name, HFSKeyCompareType compareType, bool isHFSX)
-        {
-            ParentId = parentId;
-            Name = name;
-            _comparer = GetComparer(compareType, isHFSX);
-        }
-
-        public HFSCatalogKey(byte[] key, HFSKeyCompareType compareType, bool isHFSX)
-        {
-            ReadOnlySpan<byte> data = key.AsSpan();
-            ParentId = ReadUInt32(ref data);
-            Name = ReadString(ref data, true);
-            _comparer = GetComparer(compareType, isHFSX);
-        }
-
-        public bool Equals(HFSCatalogKey? other)
-        {
-            if (other is null) return false;
-            else return (ParentId == other.ParentId) && _comparer.Equals(Name, other.Name);
-        }
-
-        public override bool Equals(object? obj)
-        {
-            if (obj is HFSCatalogKey other) return Equals(other);
-            else return false;
-        }
-
-        public int CompareTo(HFSCatalogKey? other)
-        {
-            if (other is null) return 1;
-
-            int result = ParentId.CompareTo(other.ParentId);
-            if (result == 0) result = _comparer.Compare(Name, other.Name);
-            return result;
-        }
-
-        public int CompareTo(object? obj)
-        {
-            if (obj is null) return 1;
-            else if (obj is HFSCatalogKey other) return CompareTo(other);
-            else throw new ArgumentException("Object is not of type CatalogKey", nameof(obj));
-        }
-
-        public override int GetHashCode()
-            => ParentId.GetHashCode() ^ _comparer.GetHashCode(Name);
-
-        public static bool operator ==(HFSCatalogKey? left, HFSCatalogKey? right)
-        {
-            if (left is null) return right is null;
-            else return left.Equals(right);
-        }
-
-        public static bool operator !=(HFSCatalogKey? left, HFSCatalogKey? right)
-        {
-            if (left is null) return right is not null;
-            else return !left.Equals(right);
-        }
-
-        public static bool operator <(HFSCatalogKey? left, HFSCatalogKey? right)
-        {
-            if (left is null) return right is not null;
-            else return left.CompareTo(right) < 0;
-        }
-
-        public static bool operator >(HFSCatalogKey? left, HFSCatalogKey? right)
-        {
-            if (left is null) return false;
-            else return left.CompareTo(right) > 0;
-        }
-
-        public static bool operator <=(HFSCatalogKey? left, HFSCatalogKey? right)
-        {
-            if (left is null) return true;
-            else return left.CompareTo(right) <= 0;
-        }
-
-        public static bool operator >=(HFSCatalogKey? left, HFSCatalogKey? right)
-        {
-            if (left is null) return right is null;
-            else return left.CompareTo(right) >= 0;
-        }
-    }
-
-    internal enum HFSCatalogRecordType : ushort
-    {
-        Folder = 0x0001,
-        File = 0x0002,
-        FolderThread = 0x0003,
-        FileThread = 0x0004
-    }
-
-    internal abstract class HFSCatalogRecord : HFSStructBase
-    {
-        public HFSCatalogRecordType Type { get; }
-
-        protected HFSCatalogRecord(HFSCatalogRecordType type)
-            => Type = type;
-
-        public static bool TryRead(ref ReadOnlySpan<byte> data, HFSKeyCompareType compareType, bool isHFSX, out HFSCatalogRecord? record)
-        {
-            record = null;
-
-            ushort rawType = ReadUInt16(ref data);
-            if (!Enum.IsDefined(typeof(HFSCatalogRecordType), rawType)) return false;
-
-            var type = (HFSCatalogRecordType)rawType;
-            switch (type)
-            {
-                case HFSCatalogRecordType.Folder:
-                    record = HFSCatalogFolder.Read(ref data);
-                    return true;
-
-                case HFSCatalogRecordType.File:
-                    record = HFSCatalogFile.Read(ref data);
-                    return true;
-
-                case HFSCatalogRecordType.FolderThread:
-                    record = HFSCatalogThread.Read(ref data, false, compareType, isHFSX);
-                    return true;
-
-                case HFSCatalogRecordType.FileThread:
-                    record = HFSCatalogThread.Read(ref data, true, compareType, isHFSX);
-                    return true;
-            }
-
-            return false;
-        }
-    }
-
-    internal sealed class HFSCatalogFolder : HFSCatalogRecord
-    {
-        public uint Valence { get; }
-        public uint FolderId { get; }
-        public DateTime CreateDate { get; }
-        public DateTime ContentModDate { get; }
-        public DateTime AttributeModDate { get; }
-        public DateTime AccessDate { get; }
-        public DateTime BackupDate { get; }
-        public HFSPermissions Permissions { get; }
-        public HFSFolderInfo Info { get; }
-        public uint TextEncoding { get; }
-
-        private HFSCatalogFolder(
-            uint valence,
-            uint folderId,
-            DateTime createDate,
-            DateTime contentModDate,
-            DateTime attributeModDate,
-            DateTime accessDate,
-            DateTime backupDate,
-            HFSPermissions permissions,
-            HFSFolderInfo info,
-            uint textEncoding)
-            : base(HFSCatalogRecordType.Folder)
-        {
-            Valence = valence;
-            FolderId = folderId;
-            CreateDate = createDate;
-            ContentModDate = contentModDate;
-            AttributeModDate = attributeModDate;
-            AccessDate = accessDate;
-            BackupDate = backupDate;
-            Permissions = permissions;
-            Info = info;
-            TextEncoding = textEncoding;
-        }
-
-        public static HFSCatalogFolder Read(ref ReadOnlySpan<byte> data)
-        {
-            _ = ReadUInt16(ref data); // reserved
-            uint valence = ReadUInt32(ref data);
-            uint folderId = ReadUInt32(ref data);
-            var createDate = ReadDate(ref data);
-            var contentModDate = ReadDate(ref data);
-            var attributeModDate = ReadDate(ref data);
-            var accessDate = ReadDate(ref data);
-            var backupDate = ReadDate(ref data);
-            var permissions = HFSPermissions.Read(ref data);
-            var info = HFSFolderInfo.Read(ref data);
-            uint textEncoding = ReadUInt32(ref data);
-            _ = ReadUInt32(ref data); // reserved
-
-            return new HFSCatalogFolder(
-                valence,
-                folderId,
-                createDate,
-                contentModDate,
-                attributeModDate,
-                accessDate,
-                backupDate,
-                permissions,
-                info,
-                textEncoding);
-        }
-    }
-
-    internal enum HFSFileFlags : ushort
-    {
-        LockedBit = 0x0000,
-        LockedMask = 0x0001,
-        ThreadExistsBit = 0x0001,
-        ThreadExistsMask = 0x0002
-    }
-
-    internal sealed class HFSCatalogFile : HFSCatalogRecord
-    {
-        public HFSFileFlags Flags { get; }
-        public uint FileId { get; }
-        public DateTime CreateDate { get; }
-        public DateTime ContentModDate { get; }
-        public DateTime AttributeModDate { get; }
-        public DateTime AccessDate { get; }
-        public DateTime BackupDate { get; }
-        public HFSPermissions Permissions { get; }
-        public HFSFileInfo Info { get; }
-        public uint TextEncoding { get; }
-
-        public HFSForkData DataFork { get; }
-        public HFSForkData ResourceFork { get; }
-
-        private HFSCatalogFile(
-            HFSFileFlags flags,
-            uint fileId,
-            DateTime createDate,
-            DateTime contentModDate,
-            DateTime attributeModDate,
-            DateTime accessDate,
-            DateTime backupDate,
-            HFSPermissions permissions,
-            HFSFileInfo info,
-            uint textEncoding,
-            HFSForkData dataFork,
-            HFSForkData resourceFork)
-            :base(HFSCatalogRecordType.File)
-        {
-            Flags = flags;
-            FileId = fileId;
-            CreateDate = createDate;
-            ContentModDate = contentModDate;
-            AttributeModDate = attributeModDate;
-            AccessDate = accessDate;
-            BackupDate = backupDate;
-            Permissions = permissions;
-            Info = info;
-            TextEncoding = textEncoding;
-            DataFork = dataFork;
-            ResourceFork = resourceFork;
-        }
-
-        public static HFSCatalogFile Read(ref ReadOnlySpan<byte> data)
-        {
-            var flags = (HFSFileFlags)ReadUInt16(ref data);
-            _ = ReadUInt32(ref data); // reserved
-            uint fileId = ReadUInt32(ref data);
-            var createDate = ReadDate(ref data);
-            var contentModDate = ReadDate(ref data);
-            var attributeModDate = ReadDate(ref data);
-            var accessDate = ReadDate(ref data);
-            var backupDate = ReadDate(ref data);
-            var permissions = HFSPermissions.Read(ref data);
-            var info = HFSFileInfo.Read(ref data);
-            uint textEncoding = ReadUInt32(ref data);
-            _ = ReadUInt32(ref data); // reserved
-
-            var dataFork = HFSForkData.Read(ref data);
-            var resourceFork = HFSForkData.Read(ref data);
-
-            return new HFSCatalogFile(
-                flags,
-                fileId,
-                createDate,
-                contentModDate,
-                attributeModDate,
-                accessDate,
-                backupDate,
-                permissions,
-                info,
-                textEncoding,
-                dataFork,
-                resourceFork);
-        }
-    }
-
-    internal sealed class HFSCatalogThread : HFSCatalogRecord
-    {
-        public uint ParentId { get; }
-        public string NodeName { get; }
-        public HFSCatalogKey CatalogKey { get; }
-
-        private HFSCatalogThread(uint parentId, string nodeName, bool isFile, HFSKeyCompareType compareType, bool isHFSX)
-            : base(isFile ? HFSCatalogRecordType.FileThread : HFSCatalogRecordType.FolderThread)
-        {
-            ParentId = parentId;
-            NodeName = nodeName;
-            CatalogKey = new HFSCatalogKey(ParentId, NodeName, compareType, isHFSX);
-        }
-
-        public static HFSCatalogThread Read(ref ReadOnlySpan<byte> data, bool isFile, HFSKeyCompareType compareType, bool isHFSX)
-        {
-            _ = ReadInt16(ref data); // reserved
-            uint parentId = ReadUInt32(ref data);
-            string nodeName = ReadString(ref data, true);
-
-            return new HFSCatalogThread(parentId, nodeName, isFile, compareType, isHFSX);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSExtentDescriptor.cs

@@ -1,31 +0,0 @@
-using System;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal sealed class HFSExtentDescriptor : HFSStructBase
-    {
-        public uint StartBlock { get; }
-        public uint BlockCount { get; }
-
-        private HFSExtentDescriptor(uint startBlock, uint blockCount)
-        {
-            StartBlock = startBlock;
-            BlockCount = blockCount;
-        }
-
-        public static HFSExtentDescriptor Read(Stream stream)
-        {
-            return new HFSExtentDescriptor(
-                ReadUInt32(stream),
-                ReadUInt32(stream));
-        }
-
-        public static HFSExtentDescriptor Read(ref ReadOnlySpan<byte> data)
-        {
-            return new HFSExtentDescriptor(
-                ReadUInt32(ref data),
-                ReadUInt32(ref data));
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSExtentRecord.cs

@@ -1,115 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal sealed class HFSExtentKey : HFSStructBase, IEquatable<HFSExtentKey>, IComparable<HFSExtentKey>, IComparable
-    {
-        public byte ForkType { get; }
-        public uint FileId { get; }
-        public uint StartBlock { get; }
-
-        public HFSExtentKey(byte forkType, uint fileId, uint startBlock)
-        {
-            ForkType = forkType;
-            FileId = fileId;
-            StartBlock = startBlock;
-        }
-
-        public HFSExtentKey(byte[] key)
-        {
-            ReadOnlySpan<byte> data = key.AsSpan();
-            ForkType = ReadUInt8(ref data);
-            _ = ReadUInt8(ref data); // padding
-            FileId = ReadUInt32(ref data);
-            StartBlock = ReadUInt32(ref data);
-        }
-
-        public bool Equals(HFSExtentKey? other)
-        {
-            if (other is null) return false;
-            else return (ForkType == other.ForkType) && (FileId == other.FileId) && (StartBlock == other.StartBlock);
-        }
-
-        public override bool Equals(object? obj)
-        {
-            if (obj is HFSExtentKey other) return Equals(other);
-            else return false;
-        }
-
-        public int CompareTo(HFSExtentKey? other)
-        {
-            if (other is null) return 1;
-
-            int result = FileId.CompareTo(other.FileId);
-            if (result == 0) result = ForkType.CompareTo(other.ForkType);
-            if (result == 0) result = StartBlock.CompareTo(other.StartBlock);
-            return result;
-        }
-
-        public int CompareTo(object? obj)
-        {
-            if (obj is null) return 1;
-            else if (obj is HFSExtentKey other) return CompareTo(other);
-            else throw new ArgumentException("Object is not of type ExtentKey", nameof(obj));
-        }
-
-        public override int GetHashCode()
-            => ForkType.GetHashCode() ^ FileId.GetHashCode() ^ StartBlock.GetHashCode();
-
-        public static bool operator ==(HFSExtentKey? left, HFSExtentKey? right)
-        {
-            if (left is null) return right is null;
-            else return left.Equals(right);
-        }
-
-        public static bool operator !=(HFSExtentKey? left, HFSExtentKey? right)
-        {
-            if (left is null) return right is not null;
-            else return !left.Equals(right);
-        }
-
-        public static bool operator <(HFSExtentKey? left, HFSExtentKey? right)
-        {
-            if (left is null) return right is not null;
-            else return left.CompareTo(right) < 0;
-        }
-
-        public static bool operator >(HFSExtentKey? left, HFSExtentKey? right)
-        {
-            if (left is null) return false;
-            else return left.CompareTo(right) > 0;
-        }
-
-        public static bool operator <=(HFSExtentKey? left, HFSExtentKey? right)
-        {
-            if (left is null) return true;
-            else return left.CompareTo(right) <= 0;
-        }
-
-        public static bool operator >=(HFSExtentKey? left, HFSExtentKey? right)
-        {
-            if (left is null) return right is null;
-            else return left.CompareTo(right) >= 0;
-        }
-    }
-
-    internal sealed class HFSExtentRecord : HFSStructBase
-    {
-        private const int ExtentCount = 8;
-
-        public IReadOnlyList<HFSExtentDescriptor> Extents { get; }
-
-        private HFSExtentRecord(IReadOnlyList<HFSExtentDescriptor> extents)
-            => Extents = extents;
-
-        public static HFSExtentRecord Read(ref ReadOnlySpan<byte> data)
-        {
-            var extents = new HFSExtentDescriptor[ExtentCount];
-            for (int i = 0; i < ExtentCount; i++)
-                extents[i] = HFSExtentDescriptor.Read(ref data);
-
-            return new HFSExtentRecord(extents);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSFinderInfo.cs

@@ -1,145 +0,0 @@
-using System;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal struct HFSPoint
-    {
-        public short V;
-        public short H;
-    }
-
-    internal struct HFSRect
-    {
-        public short Top;
-        public short Left;
-        public short Bottom;
-        public short Right;
-    }
-
-    [Flags]
-    internal enum HFSFinderFlags : ushort
-    {
-        None = 0x0000,
-
-        IsOnDesk = 0x0001,      /* Files and folders (System 6) */
-        Color = 0x000E,         /* Files and folders */
-        IsShared = 0x0040,      /* Files only (Applications only) If */
-                                /* clear, the application needs */
-                                /* to write to its resource fork, */
-                                /* and therefore cannot be shared */
-                                /* on a server */
-        HasNoINITs = 0x0080,    /* Files only (Extensions/Control */
-                                /* Panels only) */
-                                /* This file contains no INIT resource */
-        HasBeenInited = 0x0100, /* Files only.  Clear if the file */
-                                /* contains desktop database resources */
-                                /* ('BNDL', 'FREF', 'open', 'kind'...) */
-                                /* that have not been added yet.  Set */
-                                /* only by the Finder. */
-                                /* Reserved for folders */
-        HasCustomIcon = 0x0400, /* Files and folders */
-        IsStationery = 0x0800,  /* Files only */
-        NameLocked = 0x1000,    /* Files and folders */
-        HasBundle = 0x2000,     /* Files only */
-        IsInvisible = 0x4000,   /* Files and folders */
-        IsAlias = 0x8000        /* Files only */
-    }
-
-    [Flags]
-    internal enum HFSExtendedFinderFlags : ushort
-    {
-        None = 0x0000,
-
-        ExtendedFlagsAreInvalid = 0x8000, /* The other extended flags */
-                                          /* should be ignored */
-        HasCustomBadge = 0x0100,          /* The file or folder has a */
-                                          /* badge resource */
-        HasRoutingInfo = 0x0004           /* The file contains routing */
-                                          /* info resource */
-    }
-
-    internal sealed class HFSFileInfo : HFSStructBase
-    {
-        public string FileType { get; }             /* The type of the file */
-        public string FileCreator { get; }          /* The file's creator */
-        public HFSFinderFlags FinderFlags { get; }
-        public HFSPoint Location { get; }           /* File's location in the folder. */
-        public HFSExtendedFinderFlags ExtendedFinderFlags { get; }
-        public int PutAwayFolderId { get; }
-
-        private HFSFileInfo(
-            string fileType,
-            string fileCreator,
-            HFSFinderFlags finderFlags,
-            HFSPoint location,
-            HFSExtendedFinderFlags extendedFinderFlags,
-            int putAwayFolderId)
-        {
-            FileType = fileType;
-            FileCreator = fileCreator;
-            FinderFlags = finderFlags;
-            Location = location;
-            ExtendedFinderFlags = extendedFinderFlags;
-            PutAwayFolderId = putAwayFolderId;
-        }
-
-        public static HFSFileInfo Read(ref ReadOnlySpan<byte> data)
-        {
-            string fileType = ReadOSType(ref data);
-            string fileCreator = ReadOSType(ref data);
-            var finderFlags = (HFSFinderFlags)ReadUInt16(ref data);
-            var location = ReadPoint(ref data);
-            _ = ReadUInt16(ref data); // reserved
-            data = data.Slice(4 * sizeof(short)); // reserved
-            var extendedFinderFlags = (HFSExtendedFinderFlags)ReadUInt16(ref data);
-            _ = ReadInt16(ref data); // reserved
-            int putAwayFolderId = ReadInt32(ref data);
-
-            return new HFSFileInfo(fileType, fileCreator, finderFlags, location, extendedFinderFlags, putAwayFolderId);
-        }
-    }
-
-    internal sealed class HFSFolderInfo : HFSStructBase
-    {
-        public HFSRect WindowBounds { get; }    /* The position and dimension of the */
-                                                /* folder's window */
-        public HFSFinderFlags FinderFlags { get; }
-        public HFSPoint Location { get; }       /* Folder's location in the parent */
-                                                /* folder. If set to {0, 0}, the Finder */
-                                                /* will place the item automatically */
-        public HFSPoint ScrollPosition { get; } /* Scroll position (for icon views) */
-        public HFSExtendedFinderFlags ExtendedFinderFlags { get; }
-        public int PutAwayFolderId { get; }
-
-        private HFSFolderInfo(
-            HFSRect windowBounds,
-            HFSFinderFlags finderFlags,
-            HFSPoint location,
-            HFSPoint scrollPosition,
-            HFSExtendedFinderFlags extendedFinderFlags,
-            int putAwayFolderId)
-        {
-            WindowBounds = windowBounds;
-            FinderFlags = finderFlags;
-            Location = location;
-            ScrollPosition = scrollPosition;
-            ExtendedFinderFlags = extendedFinderFlags;
-            PutAwayFolderId = putAwayFolderId;
-        }
-
-        public static HFSFolderInfo Read(ref ReadOnlySpan<byte> data)
-        {
-            var windowBounds = ReadRect(ref data);
-            var finderFlags = (HFSFinderFlags)ReadUInt16(ref data);
-            var location = ReadPoint(ref data);
-            _ = ReadUInt16(ref data); // reserved
-            var scrollPosition = ReadPoint(ref data);
-            _ = ReadInt32(ref data); // reserved
-            var extendedFinderFlags = (HFSExtendedFinderFlags)ReadUInt16(ref data);
-            _ = ReadInt16(ref data); // reserved
-            int putAwayFolderId = ReadInt32(ref data);
-
-            return new HFSFolderInfo(windowBounds, finderFlags, location, scrollPosition, extendedFinderFlags, putAwayFolderId);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSForkData.cs

@@ -1,50 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal sealed class HFSForkData : HFSStructBase
-    {
-        private const int ExtentCount = 8;
-
-        public ulong LogicalSize { get; }
-        public uint ClumpSize { get; }
-        public uint TotalBlocks { get; }
-        public IReadOnlyList<HFSExtentDescriptor> Extents { get; }
-
-        private HFSForkData(ulong logicalSize, uint clumpSize, uint totalBlocks, IReadOnlyList<HFSExtentDescriptor> extents)
-        {
-            LogicalSize = logicalSize;
-            ClumpSize = clumpSize;
-            TotalBlocks = totalBlocks;
-            Extents = extents;
-        }
-
-        public static HFSForkData Read(Stream stream)
-        {
-            ulong logicalSize = ReadUInt64(stream);
-            uint clumpSize = ReadUInt32(stream);
-            uint totalBlocks = ReadUInt32(stream);
-
-            var extents = new HFSExtentDescriptor[ExtentCount];
-            for (int i = 0; i < ExtentCount; i++)
-                extents[i] = HFSExtentDescriptor.Read(stream);
-
-            return new HFSForkData(logicalSize, clumpSize, totalBlocks, extents);
-        }
-
-        public static HFSForkData Read(ref ReadOnlySpan<byte> data)
-        {
-            ulong logicalSize = ReadUInt64(ref data);
-            uint clumpSize = ReadUInt32(ref data);
-            uint totalBlocks = ReadUInt32(ref data);
-
-            var extents = new HFSExtentDescriptor[ExtentCount];
-            for (int i = 0; i < ExtentCount; i++)
-                extents[i] = HFSExtentDescriptor.Read(ref data);
-
-            return new HFSForkData(logicalSize, clumpSize, totalBlocks, extents);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSForkStream.cs

@@ -1,196 +0,0 @@
-using SharpCompress.IO;
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal sealed class HFSForkStream : Stream
-    {
-        private readonly Stream _baseStream;
-        private readonly HFSVolumeHeader _volumeHeader;
-        private readonly IReadOnlyList<HFSExtentDescriptor> _extents;
-        private long _position;
-        private bool _isEnded;
-        private int _extentIndex;
-        private Stream? _extentStream;
-
-        public override bool CanRead => true;
-        public override bool CanWrite => false;
-        public override bool CanSeek => true;
-        public override long Length { get; }
-
-        public override long Position
-        {
-            get => _position;
-            set
-            {
-                if ((value < 0) || (value > Length)) throw new ArgumentOutOfRangeException(nameof(value));
-
-                if (value == Length)
-                {
-                    // End of the stream
-
-                    _position = Length;
-                    _isEnded = true;
-                    _extentIndex = -1;
-                    _extentStream = null;
-                }
-                else if (value != _position)
-                {
-                    _position = value;
-
-                    // We first have to determine in which extent we are now, then we seek to the exact position in that extent.
-
-                    long offsetInExtent = _position;
-                    for (int i = 0; i < _extents.Count; i++)
-                    {
-                        var extent = _extents[i];
-                        long extentSize = extent.BlockCount * _volumeHeader.BlockSize;
-                        if (extentSize < offsetInExtent)
-                        {
-                            if (i == _extentIndex)
-                            {
-                                // We are in the same extent so just seek to the correct position
-                                _extentStream!.Position = offsetInExtent;
-                            }
-                            else
-                            {
-                                _extentIndex = i;
-                                _extentStream = GetExtentStream();
-                                _extentStream.Position = offsetInExtent;
-                            }
-
-                            break;
-                        }
-                        else
-                        {
-                            offsetInExtent -= extentSize;
-                        }
-                    }
-                }
-            }
-        }
-
-        public HFSForkStream(Stream baseStream, HFSVolumeHeader volumeHeader, HFSForkData forkData)
-        {
-            _baseStream = baseStream;
-            _volumeHeader = volumeHeader;
-            _extents = forkData.Extents;
-            Length = (long)forkData.LogicalSize;
-
-            _position = 0;
-            _extentIndex = -1;
-            _extentIndex = GetNextExtent();
-            _isEnded = _extentIndex < 0;
-            if (!_isEnded) _extentStream = GetExtentStream();
-        }
-
-        public HFSForkStream(
-            Stream baseStream, HFSVolumeHeader volumeHeader, HFSForkData forkData, uint fileId,
-            IReadOnlyDictionary<HFSExtentKey, HFSExtentRecord> extents)
-        {
-            _baseStream = baseStream;
-            _volumeHeader = volumeHeader;
-            Length = (long)forkData.LogicalSize;
-
-            uint blocks = (uint)forkData.Extents.Sum(e => e.BlockCount);
-            var totalExtents = new List<HFSExtentDescriptor>(forkData.Extents);
-            _extents = totalExtents;
-
-            var nextKey = new HFSExtentKey(0, fileId, blocks);
-            while (extents.TryGetValue(nextKey, out var record))
-            {
-                blocks += (uint)record.Extents.Sum(e => e.BlockCount);
-                totalExtents.AddRange(record.Extents);
-
-                nextKey = new HFSExtentKey(0, fileId, blocks);
-            }
-
-            _position = 0;
-            _extentIndex = -1;
-            _extentIndex = GetNextExtent();
-            _isEnded = _extentIndex < 0;
-            if (!_isEnded) _extentStream = GetExtentStream();
-        }
-
-        private int GetNextExtent()
-        {
-            int index = _extentIndex + 1;
-            if (index >= _extents.Count) return -1;
-
-            var extent = _extents[index];
-            if ((extent.StartBlock == 0) && (extent.BlockCount == 0)) return -1;
-            return index;
-        }
-
-        private Stream GetExtentStream()
-        {
-            if (_extentIndex < 0)
-                throw new InvalidOperationException("Invalid extent index");
-
-            var extent = _extents[_extentIndex];
-            return new HFSExtentStream(_baseStream, _volumeHeader, extent);
-        }
-
-        public override void Flush()
-        { }
-
-        public override int Read(byte[] buffer, int offset, int count)
-        {
-            if (_isEnded) return 0;
-
-            count = (int)Math.Min(count, Length - Position);
-            int readCount = _extentStream!.Read(buffer, offset, count);
-            while (readCount < count)
-            {
-                _extentIndex = GetNextExtent();
-                if (_extentIndex < 0)
-                {
-                    _isEnded = true;
-                    return readCount;
-                }
-
-                _extentStream = GetExtentStream();
-                readCount += _extentStream.Read(buffer, offset + readCount, count - readCount);
-            }
-
-            _position += readCount;
-            return readCount;
-        }
-
-        public override long Seek(long offset, SeekOrigin origin)
-        {
-            switch (origin)
-            {
-                case SeekOrigin.Begin:
-                    Position = offset;
-                    break;
-
-                case SeekOrigin.Current:
-                    Position += offset;
-                    break;
-
-                case SeekOrigin.End:
-                    Position = Length - offset;
-                    break;
-            }
-
-            return Position;
-        }
-
-        public override void SetLength(long value)
-            => throw new NotSupportedException();
-
-        public override void Write(byte[] buffer, int offset, int count)
-            => throw new NotSupportedException();
-
-        private sealed class HFSExtentStream : SeekableSubStream
-        {
-            public HFSExtentStream(Stream stream, HFSVolumeHeader volumeHeader, HFSExtentDescriptor extent)
-                : base(stream, (long)extent.StartBlock * volumeHeader.BlockSize, (long)extent.BlockCount * volumeHeader.BlockSize)
-            { }
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSKeyedRecord.cs

@@ -1,91 +0,0 @@
-using System;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal abstract class HFSKeyedRecord : HFSStructBase
-    {
-        private readonly HFSKeyCompareType _compareType;
-        private readonly bool _isHFSX;
-        private HFSCatalogKey? _catalogKey;
-        private HFSExtentKey? _extentKey;
-
-        public byte[] Key { get; }
-
-        public HFSCatalogKey GetCatalogKey() => _catalogKey ??= new HFSCatalogKey(Key, _compareType, _isHFSX);
-
-        public HFSExtentKey GetExtentKey() => _extentKey ??= new HFSExtentKey(Key);
-
-        protected HFSKeyedRecord(byte[] key, HFSKeyCompareType compareType, bool isHFSX)
-        {
-            Key = key;
-            _compareType = compareType;
-            _isHFSX = isHFSX;
-        }
-    }
-
-    internal sealed class HFSPointerRecord : HFSKeyedRecord
-    {
-        public uint NodeNumber { get; }
-
-        private HFSPointerRecord(byte[] key, uint nodeNumber, HFSKeyCompareType compareType, bool isHFSX)
-            : base(key, compareType, isHFSX)
-        {
-            NodeNumber = nodeNumber;
-        }
-
-        public static HFSPointerRecord Read(ref ReadOnlySpan<byte> data, HFSTreeHeaderRecord headerRecord, bool isHFSX)
-        {
-            bool isBigKey = headerRecord.Attributes.HasFlag(HFSTreeAttributes.BigKeys);
-            ushort keyLength = isBigKey ? ReadUInt16(ref data) : ReadUInt8(ref data);
-            if (!headerRecord.Attributes.HasFlag(HFSTreeAttributes.VariableIndexKeys)) keyLength = headerRecord.MaxKeyLength;
-            int keySize = (isBigKey ? 2 : 1) + keyLength;
-
-            var key = new byte[keyLength];
-            data.Slice(0, keyLength).CopyTo(key);
-            data = data.Slice(keyLength);
-
-            // data is always aligned to 2 bytes
-            if (keySize % 2 == 1) data = data.Slice(1);
-
-            uint nodeNumber = ReadUInt32(ref data);
-
-            return new HFSPointerRecord(key, nodeNumber, headerRecord.KeyCompareType, isHFSX);
-        }
-    }
-
-    internal sealed class HFSDataRecord : HFSKeyedRecord
-    {
-        public byte[] Data { get; }
-
-        private HFSDataRecord(byte[] key, byte[] data, HFSKeyCompareType compareType, bool isHFSX)
-            : base(key, compareType, isHFSX)
-        {
-            Data = data;
-        }
-
-        public static HFSDataRecord Read(ref ReadOnlySpan<byte> data, int size, HFSTreeHeaderRecord headerRecord, bool isHFSX)
-        {
-            bool isBigKey = headerRecord.Attributes.HasFlag(HFSTreeAttributes.BigKeys);
-            ushort keyLength = isBigKey ? ReadUInt16(ref data) : ReadUInt8(ref data);
-            int keySize = (isBigKey ? 2 : 1) + keyLength;
-            size -= keySize;
-
-            var key = new byte[keyLength];
-            data.Slice(0, keyLength).CopyTo(key);
-            data = data.Slice(keyLength);
-
-            // data is always aligned to 2 bytes
-            if (keySize % 2 == 1)
-            {
-                data = data.Slice(1);
-                size--;
-            }
-
-            var structData = new byte[size];
-            data.Slice(0, size).CopyTo(structData);
-            data = data.Slice(size);
-
-            return new HFSDataRecord(key, structData, headerRecord.KeyCompareType, isHFSX);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSPermissions.cs

@@ -1,35 +0,0 @@
-using System;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal sealed class HFSPermissions : HFSStructBase
-    {
-        public uint OwnerID { get; }
-        public uint GroupID { get; }
-        public byte AdminFlags { get; }
-        public byte OwnerFlags { get; }
-        public ushort FileMode { get; }
-        public uint Special { get; }
-
-        private HFSPermissions(uint ownerID, uint groupID, byte adminFlags, byte ownerFlags, ushort fileMode, uint special)
-        {
-            OwnerID = ownerID;
-            GroupID = groupID;
-            AdminFlags = adminFlags;
-            OwnerFlags = ownerFlags;
-            FileMode = fileMode;
-            Special = special;
-        }
-
-        public static HFSPermissions Read(ref ReadOnlySpan<byte> data)
-        {
-            return new HFSPermissions(
-                ReadUInt32(ref data),
-                ReadUInt32(ref data),
-                ReadUInt8(ref data),
-                ReadUInt8(ref data),
-                ReadUInt16(ref data),
-                ReadUInt32(ref data));
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSStructBase.cs

@@ -1,187 +0,0 @@
-using System;
-using System.Buffers.Binary;
-using System.IO;
-using System.Text;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal abstract class HFSStructBase
-    {
-        private const int StringSize = 510;
-        private const int OSTypeSize = 4;
-        private static readonly DateTime Epoch = new DateTime(1904, 1, 1, 0, 0, 0, DateTimeKind.Utc);
-        private static readonly byte[] _buffer = new byte[StringSize];
-
-        protected static byte ReadUInt8(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(byte)) != sizeof(byte))
-                throw new EndOfStreamException();
-
-            return _buffer[0];
-        }
-
-        protected static ushort ReadUInt16(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(ushort)) != sizeof(ushort))
-                throw new EndOfStreamException();
-
-            return BinaryPrimitives.ReadUInt16BigEndian(_buffer);
-        }
-
-        protected static short ReadInt16(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(short)) != sizeof(short))
-                throw new EndOfStreamException();
-
-            return BinaryPrimitives.ReadInt16BigEndian(_buffer);
-        }
-
-        protected static uint ReadUInt32(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(uint)) != sizeof(uint))
-                throw new EndOfStreamException();
-
-            return BinaryPrimitives.ReadUInt32BigEndian(_buffer);
-        }
-
-        protected static int ReadInt32(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(int)) != sizeof(int))
-                throw new EndOfStreamException();
-
-            return BinaryPrimitives.ReadInt32BigEndian(_buffer);
-        }
-
-        protected static ulong ReadUInt64(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(ulong)) != sizeof(ulong))
-                throw new EndOfStreamException();
-
-            return BinaryPrimitives.ReadUInt64BigEndian(_buffer);
-        }
-
-        protected static long ReadInt64(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(long)) != sizeof(long))
-                throw new EndOfStreamException();
-
-            return BinaryPrimitives.ReadInt64BigEndian(_buffer);
-        }
-
-        protected static string ReadString(Stream stream)
-        {
-            ushort length = ReadUInt16(stream);
-            if (stream.Read(_buffer, 0, StringSize) != StringSize)
-                throw new EndOfStreamException();
-            return Encoding.Unicode.GetString(_buffer, 0, Math.Min(length * 2, StringSize));
-        }
-
-        protected static DateTime ReadDate(Stream stream)
-        {
-            uint seconds = ReadUInt32(stream);
-            var span = TimeSpan.FromSeconds(seconds);
-            return Epoch + span;
-        }
-
-        protected static byte ReadUInt8(ref ReadOnlySpan<byte> data)
-        {
-            byte val = data[0];
-            data = data.Slice(sizeof(byte));
-            return val;
-        }
-
-        protected static ushort ReadUInt16(ref ReadOnlySpan<byte> data)
-        {
-            ushort val = BinaryPrimitives.ReadUInt16BigEndian(data);
-            data = data.Slice(sizeof(ushort));
-            return val;
-        }
-
-        protected static short ReadInt16(ref ReadOnlySpan<byte> data)
-        {
-            short val = BinaryPrimitives.ReadInt16BigEndian(data);
-            data = data.Slice(sizeof(short));
-            return val;
-        }
-
-        protected static uint ReadUInt32(ref ReadOnlySpan<byte> data)
-        {
-            uint val = BinaryPrimitives.ReadUInt32BigEndian(data);
-            data = data.Slice(sizeof(uint));
-            return val;
-        }
-
-        protected static int ReadInt32(ref ReadOnlySpan<byte> data)
-        {
-            int val = BinaryPrimitives.ReadInt32BigEndian(data);
-            data = data.Slice(sizeof(int));
-            return val;
-        }
-
-        protected static ulong ReadUInt64(ref ReadOnlySpan<byte> data)
-        {
-            ulong val = BinaryPrimitives.ReadUInt64BigEndian(data);
-            data = data.Slice(sizeof(ulong));
-            return val;
-        }
-
-        protected static long ReadInt64(ref ReadOnlySpan<byte> data)
-        {
-            long val = BinaryPrimitives.ReadInt64BigEndian(data);
-            data = data.Slice(sizeof(long));
-            return val;
-        }
-
-        protected static string ReadString(ref ReadOnlySpan<byte> data, bool truncate)
-        {
-            int length = ReadUInt16(ref data);
-            if (truncate)
-            {
-                length = Math.Min(length * 2, StringSize);
-                data.Slice(0, length).CopyTo(_buffer);
-                data = data.Slice(length);
-                return Encoding.BigEndianUnicode.GetString(_buffer, 0, length);
-            }
-            else
-            {
-                data.Slice(0, StringSize).CopyTo(_buffer);
-                data = data.Slice(StringSize);
-                return Encoding.BigEndianUnicode.GetString(_buffer, 0, Math.Min(length * 2, StringSize));
-            }
-        }
-
-        protected static DateTime ReadDate(ref ReadOnlySpan<byte> data)
-        {
-            uint seconds = ReadUInt32(ref data);
-            var span = TimeSpan.FromSeconds(seconds);
-            return Epoch + span;
-        }
-
-        protected static string ReadOSType(ref ReadOnlySpan<byte> data)
-        {
-            data.Slice(0, OSTypeSize).CopyTo(_buffer);
-            data = data.Slice(OSTypeSize);
-            return Encoding.ASCII.GetString(_buffer, 0, OSTypeSize).NullTerminate();
-        }
-
-        protected static HFSPoint ReadPoint(ref ReadOnlySpan<byte> data)
-        {
-            return new HFSPoint()
-            {
-                V = ReadInt16(ref data),
-                H = ReadInt16(ref data)
-            };
-        }
-
-        protected static HFSRect ReadRect(ref ReadOnlySpan<byte> data)
-        {
-            return new HFSRect()
-            {
-                Top = ReadInt16(ref data),
-                Left = ReadInt16(ref data),
-                Bottom = ReadInt16(ref data),
-                Right = ReadInt16(ref data)
-            };
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSTreeHeaderRecord.cs

@@ -1,108 +0,0 @@
-using System;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal enum HFSTreeType : byte
-    {
-        HFS = 0,         // control file
-        User = 128,      // user btree type starts from 128
-        Reserved = 255
-    }
-
-    internal enum HFSKeyCompareType : byte
-    {
-        CaseFolding = 0xCF,	  // case-insensitive
-        BinaryCompare = 0xBC  // case-sensitive
-    }
-
-    [Flags]
-    internal enum HFSTreeAttributes : uint
-    {
-        None = 0x00000000,
-        BadClose = 0x00000001,
-        BigKeys = 0x00000002,
-        VariableIndexKeys = 0x00000004
-    }
-
-    internal sealed class HFSTreeHeaderRecord : HFSStructBase
-    {
-        public ushort TreeDepth;
-        public uint RootNode;
-        public uint LeafRecords;
-        public uint FirstLeafNode;
-        public uint LastLeafNode;
-        public ushort NodeSize;
-        public ushort MaxKeyLength;
-        public uint TotalNodes;
-        public uint FreeNodes;
-        public uint ClumpSize;
-        public HFSTreeType TreeType;
-        public HFSKeyCompareType KeyCompareType;
-        public HFSTreeAttributes Attributes;
-
-        private HFSTreeHeaderRecord(
-            ushort treeDepth,
-            uint rootNode,
-            uint leafRecords,
-            uint firstLeafNode,
-            uint lastLeafNode,
-            ushort nodeSize,
-            ushort maxKeyLength,
-            uint totalNodes,
-            uint freeNodes,
-            uint clumpSize,
-            HFSTreeType treeType,
-            HFSKeyCompareType keyCompareType,
-            HFSTreeAttributes attributes)
-        {
-            TreeDepth = treeDepth;
-            RootNode = rootNode;
-            LeafRecords = leafRecords;
-            FirstLeafNode = firstLeafNode;
-            LastLeafNode = lastLeafNode;
-            NodeSize = nodeSize;
-            MaxKeyLength = maxKeyLength;
-            TotalNodes = totalNodes;
-            FreeNodes = freeNodes;
-            ClumpSize = clumpSize;
-            TreeType = treeType;
-            KeyCompareType = keyCompareType;
-            Attributes = attributes;
-        }
-
-        public static HFSTreeHeaderRecord Read(Stream stream)
-        {
-            ushort treeDepth = ReadUInt16(stream);
-            uint rootNode = ReadUInt32(stream);
-            uint leafRecords = ReadUInt32(stream);
-            uint firstLeafNode = ReadUInt32(stream);
-            uint lastLeafNode = ReadUInt32(stream);
-            ushort nodeSize = ReadUInt16(stream);
-            ushort maxKeyLength = ReadUInt16(stream);
-            uint totalNodes = ReadUInt32(stream);
-            uint freeNodes = ReadUInt32(stream);
-            _ = ReadUInt16(stream); // reserved
-            uint clumpSize = ReadUInt32(stream);
-            var treeType = (HFSTreeType)ReadUInt8(stream);
-            var keyCompareType = (HFSKeyCompareType)ReadUInt8(stream);
-            var attributes = (HFSTreeAttributes)ReadUInt32(stream);
-            for (int i = 0; i < 16; i++) _ = ReadUInt32(stream); // reserved
-
-            return new HFSTreeHeaderRecord(
-                treeDepth,
-                rootNode,
-                leafRecords,
-                firstLeafNode,
-                lastLeafNode,
-                nodeSize,
-                maxKeyLength,
-                totalNodes,
-                freeNodes,
-                clumpSize,
-                treeType,
-                keyCompareType,
-                attributes);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSTreeNode.cs

@@ -1,167 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal abstract class HFSTreeNode : HFSStructBase
-    {
-        private static byte[]? _buffer = null;
-
-        public HFSTreeNodeDescriptor Descriptor { get; }
-
-        protected HFSTreeNode(HFSTreeNodeDescriptor descriptor)
-            => Descriptor = descriptor;
-
-        public static bool TryRead(Stream stream, HFSTreeHeaderRecord headerRecord, bool isHFSX, out HFSTreeNode? node)
-        {
-            node = null;
-
-            if (!HFSTreeNodeDescriptor.TryRead(stream, out var descriptor)) return false;
-
-            int size = (int)headerRecord.NodeSize - HFSTreeNodeDescriptor.Size;
-            if ((_buffer is null) || (_buffer.Length < size))
-                _buffer = new byte[size * 2];
-
-            if (stream.Read(_buffer, 0, size) != size)
-                throw new EndOfStreamException();
-            ReadOnlySpan<byte> data = _buffer.AsSpan(0, size);
-
-            switch (descriptor!.Kind)
-            {
-                case HFSTreeNodeKind.Leaf:
-                    node = HFSLeafTreeNode.Read(descriptor, data, headerRecord, isHFSX);
-                    return true;
-
-                case HFSTreeNodeKind.Index:
-                    node = HFSIndexTreeNode.Read(descriptor, data, headerRecord, isHFSX);
-                    return true;
-
-                case HFSTreeNodeKind.Map:
-                    node = HFSMapTreeNode.Read(descriptor, data);
-                    return true;
-            }
-
-            return false;
-        }
-    }
-
-    internal sealed class HFSHeaderTreeNode : HFSTreeNode
-    {
-        private const int UserDataSize = 128;
-
-        public HFSTreeHeaderRecord HeaderRecord { get; }
-
-        public IReadOnlyList<byte> UserData { get; }
-
-        public IReadOnlyList<byte> Map { get; }
-
-        private HFSHeaderTreeNode(
-            HFSTreeNodeDescriptor descriptor,
-            HFSTreeHeaderRecord headerRecord,
-            IReadOnlyList<byte> userData,
-            IReadOnlyList<byte> map)
-            : base(descriptor)
-        {
-            HeaderRecord = headerRecord;
-            UserData = userData;
-            Map = map;
-        }
-
-        public static HFSHeaderTreeNode Read(HFSTreeNodeDescriptor descriptor, Stream stream)
-        {
-            if (descriptor.Kind != HFSTreeNodeKind.Header)
-                throw new ArgumentException("Descriptor does not define a header node");
-
-            var headerRecord = HFSTreeHeaderRecord.Read(stream);
-            var userData = new byte[UserDataSize];
-            if (stream.Read(userData, 0, UserDataSize) != UserDataSize)
-                throw new EndOfStreamException();
-
-            int mapSize = (int)(headerRecord.NodeSize - 256);
-            var map = new byte[mapSize];
-            if (stream.Read(map, 0, mapSize) != mapSize)
-                throw new EndOfStreamException();
-
-            // offset values (not required for header node)
-            _ = ReadUInt16(stream);
-            _ = ReadUInt16(stream);
-            _ = ReadUInt16(stream);
-            _ = ReadUInt16(stream);
-
-            return new HFSHeaderTreeNode(descriptor, headerRecord, userData, map);
-        }
-    }
-
-    internal sealed class HFSMapTreeNode : HFSTreeNode
-    {
-        public IReadOnlyList<byte> Map { get; }
-
-        private HFSMapTreeNode(HFSTreeNodeDescriptor descriptor, IReadOnlyList<byte> map)
-            : base(descriptor)
-        {
-            Map = map;
-        }
-
-        public static HFSMapTreeNode Read(HFSTreeNodeDescriptor descriptor, ReadOnlySpan<byte> data)
-        {
-            int mapSize = data.Length - 6;
-            var map = new byte[mapSize];
-            data.Slice(0, mapSize).CopyTo(map);
-
-            return new HFSMapTreeNode(descriptor, map);
-        }
-    }
-
-    internal sealed class HFSIndexTreeNode : HFSTreeNode
-    {
-        public IReadOnlyList<HFSPointerRecord> Records { get; }
-
-        private HFSIndexTreeNode(HFSTreeNodeDescriptor descriptor, IReadOnlyList<HFSPointerRecord> records)
-            : base(descriptor)
-        {
-            Records = records;
-        }
-
-        public static HFSIndexTreeNode Read(HFSTreeNodeDescriptor descriptor, ReadOnlySpan<byte> data, HFSTreeHeaderRecord headerRecord, bool isHFSX)
-        {
-            int recordCount = descriptor.NumRecords;
-            var records = new HFSPointerRecord[recordCount];
-            for (int i = 0; i < recordCount; i++)
-                records[i] = HFSPointerRecord.Read(ref data, headerRecord, isHFSX);
-            return new HFSIndexTreeNode(descriptor, records);
-        }
-    }
-
-    internal sealed class HFSLeafTreeNode : HFSTreeNode
-    {
-        public IReadOnlyList<HFSDataRecord> Records { get; }
-
-        private HFSLeafTreeNode(HFSTreeNodeDescriptor descriptor, IReadOnlyList<HFSDataRecord> records)
-            : base(descriptor)
-        {
-            Records = records;
-        }
-
-        public static HFSLeafTreeNode Read(HFSTreeNodeDescriptor descriptor, ReadOnlySpan<byte> data, HFSTreeHeaderRecord headerRecord, bool isHFSX)
-        {
-            int recordCount = descriptor.NumRecords;
-            var recordOffsets = new int[recordCount + 1];
-            for (int i = 0; i < recordOffsets.Length; i++)
-            {
-                var offsetData = data.Slice(data.Length - (2 * i) - 2);
-                ushort offset = ReadUInt16(ref offsetData);
-                recordOffsets[i] = offset;
-            }
-
-            var records = new HFSDataRecord[recordCount];
-            for (int i = 0; i < recordCount; i++)
-            {
-                int size = recordOffsets[i + 1] - recordOffsets[i];
-                records[i] = HFSDataRecord.Read(ref data, size, headerRecord, isHFSX);
-            }
-
-            return new HFSLeafTreeNode(descriptor, records);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSTreeNodeDescriptor.cs

@@ -1,55 +0,0 @@
-using System;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal enum HFSTreeNodeKind : sbyte
-    {
-        Leaf = -1,
-        Index = 0,
-        Header = 1,
-        Map = 2
-    }
-
-    internal sealed class HFSTreeNodeDescriptor : HFSStructBase
-    {
-        public const int Size = 14;
-
-        public uint FLink { get; }
-        public uint BLink { get; }
-        public HFSTreeNodeKind Kind { get; }
-        public byte Height { get; }
-        public ushort NumRecords { get; }
-
-        private HFSTreeNodeDescriptor(uint fLink, uint bLink, HFSTreeNodeKind kind, byte height, ushort numRecords)
-        {
-            FLink = fLink;
-            BLink = bLink;
-            Kind = kind;
-            Height = height;
-            NumRecords = numRecords;
-        }
-
-        public static bool TryRead(Stream stream, out HFSTreeNodeDescriptor? descriptor)
-        {
-            descriptor = null;
-
-            uint fLink = ReadUInt32(stream);
-            uint bLink = ReadUInt32(stream);
-
-            sbyte rawKind = (sbyte)ReadUInt8(stream);
-            if (!Enum.IsDefined(typeof(HFSTreeNodeKind), rawKind)) return false;
-            var kind = (HFSTreeNodeKind)rawKind;
-
-            byte height = ReadUInt8(stream);
-            if (((kind == HFSTreeNodeKind.Header) || (kind == HFSTreeNodeKind.Map)) && (height != 0)) return false;
-            if ((kind == HFSTreeNodeKind.Leaf) && (height != 1)) return false;
-
-            ushort numRecords = ReadUInt16(stream);
-            _ = ReadUInt16(stream); // reserved
-
-            descriptor = new HFSTreeNodeDescriptor(fLink, bLink, kind, height, numRecords);
-            return true;
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSUtil.cs

@@ -1,206 +0,0 @@
-using SharpCompress.Archives.Dmg;
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Text;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal static class HFSUtil
-    {
-        private const string CorruptHFSMessage = "Corrupt HFS volume";
-
-        private static (HFSHeaderTreeNode, IReadOnlyList<HFSTreeNode>) ReadTree(Stream stream, bool isHFSX)
-        {
-            if (!HFSTreeNodeDescriptor.TryRead(stream, out var headerDesc))
-                throw new InvalidFormatException(CorruptHFSMessage);
-            var header = HFSHeaderTreeNode.Read(headerDesc!, stream);
-
-            var nodes = new HFSTreeNode[header.HeaderRecord.TotalNodes];
-            nodes[0] = header;
-
-            for (int i = 1; i < nodes.Length; i++)
-            {
-                if (!HFSTreeNode.TryRead(stream, header.HeaderRecord, isHFSX, out var node))
-                    throw new InvalidFormatException(CorruptHFSMessage);
-
-                nodes[i] = node!;
-            }
-
-            return (header, nodes);
-        }
-
-        private static void EnumerateExtentsTree(
-            IReadOnlyList<HFSTreeNode> extentsTree,
-            IDictionary<HFSExtentKey, HFSExtentRecord> records,
-            int parentIndex)
-        {
-            var parent = extentsTree[parentIndex];
-            if (parent is HFSLeafTreeNode leafNode)
-            {
-                foreach (var record in leafNode.Records)
-                {
-                    ReadOnlySpan<byte> data = record.Data.AsSpan();
-                    var recordData = HFSExtentRecord.Read(ref data);
-                    var key = record.GetExtentKey();
-                    records.Add(key, recordData);
-                }
-            }
-            else if (parent is HFSIndexTreeNode indexNode)
-            {
-                foreach (var record in indexNode.Records)
-                    EnumerateExtentsTree(extentsTree, records, (int)record.NodeNumber);
-            }
-            else
-            {
-                throw new InvalidFormatException(CorruptHFSMessage);
-            }
-        }
-
-        private static IReadOnlyDictionary<HFSExtentKey, HFSExtentRecord> LoadExtents(IReadOnlyList<HFSTreeNode> extentsTree, int rootIndex)
-        {
-            var records = new Dictionary<HFSExtentKey, HFSExtentRecord>();
-            if (rootIndex == 0) return records;
-
-            EnumerateExtentsTree(extentsTree, records, rootIndex);
-            return records;
-        }
-
-        private static void EnumerateCatalogTree(
-            HFSHeaderTreeNode catalogHeader,
-            IReadOnlyList<HFSTreeNode> catalogTree,
-            IDictionary<HFSCatalogKey, HFSCatalogRecord> records,
-            IDictionary<uint, HFSCatalogThread> threads,
-            int parentIndex,
-            bool isHFSX)
-        {
-            var parent = catalogTree[parentIndex];
-            if (parent is HFSLeafTreeNode leafNode)
-            {
-                foreach (var record in leafNode.Records)
-                {
-                    ReadOnlySpan<byte> data = record.Data.AsSpan();
-                    if (HFSCatalogRecord.TryRead(ref data, catalogHeader.HeaderRecord.KeyCompareType, isHFSX, out var recordData))
-                    {
-                        var key = record.GetCatalogKey();
-                        if ((recordData!.Type == HFSCatalogRecordType.FileThread) || (recordData!.Type == HFSCatalogRecordType.FolderThread))
-                        {
-                            threads.Add(key.ParentId, (HFSCatalogThread)recordData);
-                        }
-                        else
-                        {
-                            records.Add(key, recordData);
-                        }
-                    }
-                    else
-                    {
-                        throw new InvalidFormatException(CorruptHFSMessage);
-                    }
-                }
-            }
-            else if (parent is HFSIndexTreeNode indexNode)
-            {
-                foreach (var record in indexNode.Records)
-                    EnumerateCatalogTree(catalogHeader, catalogTree, records, threads, (int)record.NodeNumber, isHFSX);
-            }
-            else
-            {
-                throw new InvalidFormatException(CorruptHFSMessage);
-            }
-        }
-
-        private static (HFSCatalogKey, HFSCatalogRecord) GetRecord(uint id, IDictionary<HFSCatalogKey, HFSCatalogRecord> records, IDictionary<uint, HFSCatalogThread> threads)
-        {
-            if (threads.TryGetValue(id, out var thread))
-            {
-                if (records.TryGetValue(thread.CatalogKey, out var record))
-                    return (thread.CatalogKey, record!);
-            }
-
-            throw new InvalidFormatException(CorruptHFSMessage);
-        }
-
-        private static string SanitizePath(string path)
-        {
-            var sb = new StringBuilder(path.Length);
-            foreach (char c in path)
-            {
-                if (!char.IsControl(c))
-                    sb.Append(c);
-            }
-            return sb.ToString();
-        }
-
-        private static string GetPath(HFSCatalogKey key, IDictionary<HFSCatalogKey, HFSCatalogRecord> records, IDictionary<uint, HFSCatalogThread> threads)
-        {
-            if (key.ParentId == 1)
-            {
-                return key.Name;
-            }
-            else
-            {
-                var (parentKey, _) = GetRecord(key.ParentId, records, threads);
-                var path = Path.Combine(GetPath(parentKey, records, threads), key.Name);
-                return SanitizePath(path);
-            }
-        }
-
-        private static IEnumerable<DmgArchiveEntry> LoadEntriesFromCatalogTree(
-            Stream partitionStream,
-            DmgFilePart filePart,
-            HFSVolumeHeader volumeHeader,
-            HFSHeaderTreeNode catalogHeader,
-            IReadOnlyList<HFSTreeNode> catalogTree,
-            IReadOnlyDictionary<HFSExtentKey, HFSExtentRecord> extents,
-            DmgArchive archive,
-            int rootIndex)
-        {
-            if (rootIndex == 0) return Array.Empty<DmgArchiveEntry>();
-
-            var records = new Dictionary<HFSCatalogKey, HFSCatalogRecord>();
-            var threads = new Dictionary<uint, HFSCatalogThread>();
-            EnumerateCatalogTree(catalogHeader, catalogTree, records, threads, rootIndex, volumeHeader.IsHFSX);
-
-            var entries = new List<DmgArchiveEntry>();
-            foreach (var kvp in records)
-            {
-                var key = kvp.Key;
-                var record = kvp.Value;
-
-                string path = GetPath(key, records, threads);
-                var stream = (record is HFSCatalogFile file) ? new HFSForkStream(partitionStream, volumeHeader, file.DataFork, file.FileId, extents) : null;
-                var entry = new DmgArchiveEntry(stream, archive, record, path, filePart);
-                entries.Add(entry);
-            }
-
-            return entries;
-        }
-
-        public static IEnumerable<DmgArchiveEntry> LoadEntriesFromPartition(Stream partitionStream, string fileName, DmgArchive archive)
-        {
-            if (!HFSVolumeHeader.TryRead(partitionStream, out var volumeHeader))
-                throw new InvalidFormatException(CorruptHFSMessage);
-            var filePart = new DmgFilePart(partitionStream, fileName);
-
-            var extentsFile = volumeHeader!.ExtentsFile;
-            var extentsStream = new HFSForkStream(partitionStream, volumeHeader, extentsFile);
-            var (extentsHeader, extentsTree) = ReadTree(extentsStream, volumeHeader.IsHFSX);
-
-            var extents = LoadExtents(extentsTree, (int)extentsHeader.HeaderRecord.RootNode);
-
-            var catalogFile = volumeHeader!.CatalogFile;
-            var catalogStream = new HFSForkStream(partitionStream, volumeHeader, catalogFile);
-            var (catalogHeader, catalogTree) = ReadTree(catalogStream, volumeHeader.IsHFSX);
-
-            return LoadEntriesFromCatalogTree(
-                partitionStream,
-                filePart,
-                volumeHeader,
-                catalogHeader,
-                catalogTree,
-                extents,
-                archive,
-                (int)catalogHeader.HeaderRecord.RootNode);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/HFS/HFSVolumeHeader.cs

@@ -1,179 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg.HFS
-{
-    internal sealed class HFSVolumeHeader : HFSStructBase
-    {
-        private const ushort SignaturePlus = 0x482B;
-        private const ushort SignatureX = 0x4858;
-        private const int FinderInfoCount = 8;
-
-        public bool IsHFSX { get; }
-        public ushort Version { get; }
-        public uint Attributes { get; }
-        public uint LastMountedVersion { get; }
-        public uint JournalInfoBlock { get; }
-
-        public DateTime CreateDate { get; }
-        public DateTime ModifyDate { get; }
-        public DateTime BackupDate { get; }
-        public DateTime CheckedDate { get; }
-
-        public uint FileCount { get; }
-        public uint FolderCount { get; }
-
-        public uint BlockSize { get; }
-        public uint TotalBlocks { get; }
-        public uint FreeBlocks { get; }
-
-        public uint NextAllocation { get; }
-        public uint RsrcClumpSize { get; }
-        public uint DataClumpSize { get; }
-        public uint NextCatalogID { get; }
-
-        public uint WriteCount { get; }
-        public ulong EncodingsBitmap { get; }
-
-        public IReadOnlyList<uint> FinderInfo { get; }
-
-        public HFSForkData AllocationFile { get; }
-        public HFSForkData ExtentsFile { get; }
-        public HFSForkData CatalogFile { get; }
-        public HFSForkData AttributesFile { get; }
-        public HFSForkData StartupFile { get; }
-
-        public HFSVolumeHeader(
-            bool isHFSX,
-            ushort version,
-            uint attributes,
-            uint lastMountedVersion,
-            uint journalInfoBlock,
-            DateTime createDate,
-            DateTime modifyDate,
-            DateTime backupDate,
-            DateTime checkedDate,
-            uint fileCount,
-            uint folderCount,
-            uint blockSize,
-            uint totalBlocks,
-            uint freeBlocks,
-            uint nextAllocation,
-            uint rsrcClumpSize,
-            uint dataClumpSize,
-            uint nextCatalogID,
-            uint writeCount,
-            ulong encodingsBitmap,
-            IReadOnlyList<uint> finderInfo,
-            HFSForkData allocationFile,
-            HFSForkData extentsFile,
-            HFSForkData catalogFile,
-            HFSForkData attributesFile,
-            HFSForkData startupFile)
-        {
-            IsHFSX = isHFSX;
-            Version = version;
-            Attributes = attributes;
-            LastMountedVersion = lastMountedVersion;
-            JournalInfoBlock = journalInfoBlock;
-            CreateDate = createDate;
-            ModifyDate = modifyDate;
-            BackupDate = backupDate;
-            CheckedDate = checkedDate;
-            FileCount = fileCount;
-            FolderCount = folderCount;
-            BlockSize = blockSize;
-            TotalBlocks = totalBlocks;
-            FreeBlocks = freeBlocks;
-            NextAllocation = nextAllocation;
-            RsrcClumpSize = rsrcClumpSize;
-            DataClumpSize = dataClumpSize;
-            NextCatalogID = nextCatalogID;
-            WriteCount = writeCount;
-            EncodingsBitmap = encodingsBitmap;
-            FinderInfo = finderInfo;
-            AllocationFile = allocationFile;
-            ExtentsFile = extentsFile;
-            CatalogFile = catalogFile;
-            AttributesFile = attributesFile;
-            StartupFile = startupFile;
-        }
-
-        private static IReadOnlyList<uint> ReadFinderInfo(Stream stream)
-        {
-            var finderInfo = new uint[FinderInfoCount];
-            for (int i = 0; i < FinderInfoCount; i++)
-                finderInfo[i] = ReadUInt32(stream);
-            return finderInfo;
-        }
-
-        public static bool TryRead(Stream stream, out HFSVolumeHeader? header)
-        {
-            header = null;
-            stream.Skip(1024); // reserved bytes
-
-            bool isHFSX;
-            ushort sig = ReadUInt16(stream);
-            if (sig == SignaturePlus) isHFSX = false;
-            else if (sig == SignatureX) isHFSX = true;
-            else return false;
-
-            ushort version = ReadUInt16(stream);
-            uint attributes = ReadUInt32(stream);
-            uint lastMountedVersion = ReadUInt32(stream);
-            uint journalInfoBlock = ReadUInt32(stream);
-            DateTime createDate = ReadDate(stream);
-            DateTime modifyDate = ReadDate(stream);
-            DateTime backupDate = ReadDate(stream);
-            DateTime checkedDate = ReadDate(stream);
-            uint fileCount = ReadUInt32(stream);
-            uint folderCount = ReadUInt32(stream);
-            uint blockSize = ReadUInt32(stream);
-            uint totalBlocks = ReadUInt32(stream);
-            uint freeBlocks = ReadUInt32(stream);
-            uint nextAllocation = ReadUInt32(stream);
-            uint rsrcClumpSize = ReadUInt32(stream);
-            uint dataClumpSize = ReadUInt32(stream);
-            uint nextCatalogID = ReadUInt32(stream);
-            uint writeCount = ReadUInt32(stream);
-            ulong encodingsBitmap = ReadUInt64(stream);
-            IReadOnlyList<uint> finderInfo = ReadFinderInfo(stream);
-            HFSForkData allocationFile = HFSForkData.Read(stream);
-            HFSForkData extentsFile = HFSForkData.Read(stream);
-            HFSForkData catalogFile = HFSForkData.Read(stream);
-            HFSForkData attributesFile = HFSForkData.Read(stream);
-            HFSForkData startupFile = HFSForkData.Read(stream);
-
-            header = new HFSVolumeHeader(
-                isHFSX,
-                version,
-                attributes,
-                lastMountedVersion,
-                journalInfoBlock,
-                createDate,
-                modifyDate,
-                backupDate,
-                checkedDate,
-                fileCount,
-                folderCount,
-                blockSize,
-                totalBlocks,
-                freeBlocks,
-                nextAllocation,
-                rsrcClumpSize,
-                dataClumpSize,
-                nextCatalogID,
-                writeCount,
-                encodingsBitmap,
-                finderInfo,
-                allocationFile,
-                extentsFile,
-                catalogFile,
-                attributesFile,
-                startupFile);
-
-            return true;
-        }
-    }
-}

src/SharpCompress/Common/Dmg/Headers/BlkxChunk.cs

@@ -1,49 +0,0 @@
-using System;
-
-namespace SharpCompress.Common.Dmg.Headers
-{
-    internal enum BlkxChunkType : uint
-    {
-        Zero = 0x00000000u,
-        Uncompressed = 0x00000001u,
-        Ignore = 0x00000002u,
-        AdcCompressed = 0x80000004u,
-        ZlibCompressed = 0x80000005u,
-        Bz2Compressed = 0x80000006u,
-        Comment = 0x7FFFFFFEu,
-        Last = 0xFFFFFFFFu,
-    }
-
-    internal sealed class BlkxChunk : DmgStructBase
-    {
-        private const int SectorSize = 512;
-
-        public BlkxChunkType Type { get; }      // Compression type used or chunk type
-        public uint Comment { get; }            // "+beg" or "+end", if EntryType is comment (0x7FFFFFFE). Else reserved.
-        public ulong UncompressedOffset { get; }      // Start sector of this chunk
-        public ulong UncompressedLength { get; }       // Number of sectors in this chunk
-        public ulong CompressedOffset { get; }  // Start of chunk in data fork
-        public ulong CompressedLength { get; }  // Count of bytes of chunk, in data fork
-
-        private BlkxChunk(BlkxChunkType type, uint comment, ulong sectorNumber, ulong sectorCount, ulong compressedOffset, ulong compressedLength)
-        {
-            Type = type;
-            Comment = comment;
-            UncompressedOffset = sectorNumber * SectorSize;
-            UncompressedLength = sectorCount * SectorSize;
-            CompressedOffset = compressedOffset;
-            CompressedLength = compressedLength;
-        }
-
-        public static bool TryRead(ref ReadOnlySpan<byte> data, out BlkxChunk? chunk)
-        {
-            chunk = null;
-
-            var type = (BlkxChunkType)ReadUInt32(ref data);
-            if (!Enum.IsDefined(typeof(BlkxChunkType), type)) return false;
-
-            chunk = new BlkxChunk(type, ReadUInt32(ref data), ReadUInt64(ref data), ReadUInt64(ref data), ReadUInt64(ref data), ReadUInt64(ref data));
-            return true;
-        }
-    }
-}

src/SharpCompress/Common/Dmg/Headers/BlkxTable.cs

@@ -1,75 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace SharpCompress.Common.Dmg.Headers
-{
-    internal sealed class BlkxTable : DmgStructBase
-    {
-        private const uint Signature = 0x6d697368u;
-
-        public uint Version { get; }             // Current version is 1
-        public ulong SectorNumber { get; }       // Starting disk sector in this blkx descriptor
-        public ulong SectorCount { get; }        // Number of disk sectors in this blkx descriptor
-
-        public ulong DataOffset { get; }
-        public uint BuffersNeeded { get; }
-        public uint BlockDescriptors { get; }    // Number of descriptors
-
-        public UdifChecksum Checksum { get; }
-
-        public IReadOnlyList<BlkxChunk> Chunks { get; }
-
-        private BlkxTable(
-            uint version,
-            ulong sectorNumber,
-            ulong sectorCount,
-            ulong dataOffset,
-            uint buffersNeeded,
-            uint blockDescriptors,
-            UdifChecksum checksum,
-            IReadOnlyList<BlkxChunk> chunks)
-        {
-            Version = version;
-            SectorNumber = sectorNumber;
-            SectorCount = sectorCount;
-            DataOffset = dataOffset;
-            BuffersNeeded = buffersNeeded;
-            BlockDescriptors = blockDescriptors;
-            Checksum = checksum;
-            Chunks = chunks;
-        }
-
-        public static bool TryRead(in byte[] buffer, out BlkxTable? header)
-        {
-            header = null;
-
-            ReadOnlySpan<byte> data = buffer.AsSpan();
-
-            uint sig = ReadUInt32(ref data);
-            if (sig != Signature) return false;
-
-            uint version = ReadUInt32(ref data);
-            ulong sectorNumber = ReadUInt64(ref data);
-            ulong sectorCount = ReadUInt64(ref data);
-
-            ulong dataOffset = ReadUInt64(ref data);
-            uint buffersNeeded = ReadUInt32(ref data);
-            uint blockDescriptors = ReadUInt32(ref data);
-
-            data = data.Slice(6 * sizeof(uint)); // reserved
-
-            var checksum = UdifChecksum.Read(ref data);
-
-            uint chunkCount = ReadUInt32(ref data);
-            var chunks = new BlkxChunk[chunkCount];
-            for (int i = 0; i < chunkCount; i++)
-            {
-                if (!BlkxChunk.TryRead(ref data, out var chunk)) return false;
-                chunks[i] = chunk!;
-            }
-
-            header = new BlkxTable(version, sectorNumber, sectorCount, dataOffset, buffersNeeded, blockDescriptors, checksum, chunks);
-            return true;
-        }
-    }
-}

src/SharpCompress/Common/Dmg/Headers/DmgHeader.cs

@@ -1,138 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg.Headers
-{
-    internal sealed class DmgHeader : DmgStructBase
-    {
-        public const int HeaderSize = 512;
-        private const uint Signature = 0x6B6F6C79u;
-        private const int UuidSize = 16; // 128 bit
-
-        public uint Version { get; }                     // Current version is 4
-        public uint Flags { get; }                       // Flags
-        public ulong RunningDataForkOffset { get; }      //
-        public ulong DataForkOffset { get; }             // Data fork offset (usually 0, beginning of file)
-        public ulong DataForkLength { get; }             // Size of data fork (usually up to the XMLOffset, below)
-        public ulong RsrcForkOffset { get; }             // Resource fork offset, if any
-        public ulong RsrcForkLength { get; }             // Resource fork length, if any
-        public uint SegmentNumber { get; }               // Usually 1, may be 0
-        public uint SegmentCount { get; }                // Usually 1, may be 0
-        public IReadOnlyList<byte> SegmentID { get; }    // 128-bit GUID identifier of segment (if SegmentNumber !=0)
-
-        public UdifChecksum DataChecksum { get; }
-
-        public ulong XMLOffset { get; }                  // Offset of property list in DMG, from beginning
-        public ulong XMLLength { get; }                  // Length of property list
-
-        public UdifChecksum Checksum { get; }
-        
-        public uint ImageVariant { get; }                // Commonly 1
-        public ulong SectorCount { get; }                // Size of DMG when expanded, in sectors
-
-        private DmgHeader(
-            uint version,
-            uint flags,
-            ulong runningDataForkOffset,
-            ulong dataForkOffset,
-            ulong dataForkLength,
-            ulong rsrcForkOffset,
-            ulong rsrcForkLength,
-            uint segmentNumber,
-            uint segmentCount,
-            IReadOnlyList<byte> segmentID,
-            UdifChecksum dataChecksum,
-            ulong xMLOffset,
-            ulong xMLLength,
-            UdifChecksum checksum,
-            uint imageVariant,
-            ulong sectorCount)
-        {
-            Version = version;
-            Flags = flags;
-            RunningDataForkOffset = runningDataForkOffset;
-            DataForkOffset = dataForkOffset;
-            DataForkLength = dataForkLength;
-            RsrcForkOffset = rsrcForkOffset;
-            RsrcForkLength = rsrcForkLength;
-            SegmentNumber = segmentNumber;
-            SegmentCount = segmentCount;
-            SegmentID = segmentID;
-            DataChecksum = dataChecksum;
-            XMLOffset = xMLOffset;
-            XMLLength = xMLLength;
-            Checksum = checksum;
-            ImageVariant = imageVariant;
-            SectorCount = sectorCount;
-        }
-
-        private static void ReadUuid(ref ReadOnlySpan<byte> data, byte[] buffer)
-        {
-            data.Slice(0, UuidSize).CopyTo(buffer);
-            data = data.Slice(UuidSize);
-        }
-
-        internal static bool TryRead(Stream input, out DmgHeader? header)
-        {
-            header = null;
-
-            var buffer = new byte[HeaderSize];
-            int count = input.Read(buffer, 0, HeaderSize);
-            if (count != HeaderSize) return false;
-            ReadOnlySpan<byte> data = buffer.AsSpan();
-
-            uint sig = ReadUInt32(ref data);
-            if (sig != Signature) return false;
-
-            uint version = ReadUInt32(ref data);
-
-            uint size = ReadUInt32(ref data);
-            if (size != (uint)HeaderSize) return false;
-
-            uint flags = ReadUInt32(ref data);
-            ulong runningDataForkOffset = ReadUInt64(ref data);
-            ulong dataForkOffset = ReadUInt64(ref data);
-            ulong dataForkLength = ReadUInt64(ref data);
-            ulong rsrcForkOffset = ReadUInt64(ref data);
-            ulong rsrcForkLength = ReadUInt64(ref data);
-            uint segmentNumber = ReadUInt32(ref data);
-            uint segmentCount = ReadUInt32(ref data);
-
-            var segmentID = new byte[UuidSize];
-            ReadUuid(ref data, segmentID);
-
-            var dataChecksum = UdifChecksum.Read(ref data);
-
-            ulong xmlOffset = ReadUInt64(ref data);
-            ulong xmlLength = ReadUInt64(ref data);
-
-            data = data.Slice(120); // Reserved bytes
-
-            var checksum = UdifChecksum.Read(ref data);
-
-            uint imageVariant = ReadUInt32(ref data);
-            ulong sectorCount = ReadUInt64(ref data);
-
-            header = new DmgHeader(
-                version,
-                flags,
-                runningDataForkOffset,
-                dataForkOffset,
-                dataForkLength,
-                rsrcForkOffset,
-                rsrcForkLength,
-                segmentNumber,
-                segmentCount,
-                segmentID,
-                dataChecksum,
-                xmlOffset,
-                xmlLength,
-                checksum,
-                imageVariant,
-                sectorCount);
-
-            return true;
-        }
-    }
-}

src/SharpCompress/Common/Dmg/Headers/DmgStructBase.cs

@@ -1,22 +0,0 @@
-using System;
-using System.Buffers.Binary;
-
-namespace SharpCompress.Common.Dmg.Headers
-{
-    internal abstract class DmgStructBase
-    {
-        protected static uint ReadUInt32(ref ReadOnlySpan<byte> data)
-        {
-            uint val = BinaryPrimitives.ReadUInt32BigEndian(data);
-            data = data.Slice(sizeof(uint));
-            return val;
-        }
-
-        protected static ulong ReadUInt64(ref ReadOnlySpan<byte> data)
-        {
-            ulong val = BinaryPrimitives.ReadUInt64BigEndian(data);
-            data = data.Slice(sizeof(ulong));
-            return val;
-        }
-    }
-}

src/SharpCompress/Common/Dmg/Headers/GptHeader.cs

@@ -1,90 +0,0 @@
-using System;
-using System.Buffers.Binary;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg.Headers
-{
-    internal sealed class GptHeader : GptStructBase
-    {
-        private const int HeaderSize = 92;
-        private static readonly ulong Signature = BinaryPrimitives.ReadUInt64LittleEndian(new byte[] { 69, 70, 73, 32, 80, 65, 82, 84 });
-
-        public uint Revision { get; }
-        public uint Crc32Header { get; }
-        public ulong CurrentLba { get; }
-        public ulong BackupLba { get; }
-        public ulong FirstUsableLba { get; }
-        public ulong LastUsableLba { get; }
-        public Guid DiskGuid { get; }
-        public ulong EntriesStart { get; }
-        public uint EntriesCount { get; }
-        public uint EntriesSize { get; }
-        public uint Crc32Array { get; }
-
-        private GptHeader(
-            uint revision,
-            uint crc32Header,
-            ulong currentLba,
-            ulong backupLba,
-            ulong firstUsableLba,
-            ulong lastUsableLba,
-            Guid diskGuid,
-            ulong entriesStart,
-            uint entriesCount,
-            uint entriesSize,
-            uint crc32Array)
-        {
-            Revision = revision;
-            Crc32Header = crc32Header;
-            CurrentLba = currentLba;
-            BackupLba = backupLba;
-            FirstUsableLba = firstUsableLba;
-            LastUsableLba = lastUsableLba;
-            DiskGuid = diskGuid;
-            EntriesStart = entriesStart;
-            EntriesCount = entriesCount;
-            EntriesSize = entriesSize;
-            Crc32Array = crc32Array;
-        }
-
-        public static bool TryRead(Stream stream, out GptHeader? header)
-        {
-            header = null;
-
-            ulong sig = ReadUInt64(stream);
-            if (sig != Signature) return false;
-
-            uint revision = ReadUInt32(stream);
-
-            uint headerSize = ReadUInt32(stream);
-            if (headerSize != HeaderSize) return false;
-
-            uint crc32Header = ReadUInt32(stream);
-            _ = ReadUInt32(stream); // reserved
-            ulong currentLba = ReadUInt64(stream);
-            ulong backupLba = ReadUInt64(stream);
-            ulong firstUsableLba = ReadUInt64(stream);
-            ulong lastUsableLba = ReadUInt64(stream);
-            Guid diskGuid = ReadGuid(stream);
-            ulong entriesStart = ReadUInt64(stream);
-            uint entriesCount = ReadUInt32(stream);
-            uint entriesSize = ReadUInt32(stream);
-            uint crc32Array = ReadUInt32(stream);
-
-            header = new GptHeader(
-                revision,
-                crc32Header,
-                currentLba,
-                backupLba,
-                firstUsableLba,
-                lastUsableLba,
-                diskGuid,
-                entriesStart,
-                entriesCount,
-                entriesSize,
-                crc32Array);
-
-            return true;
-        }
-    }
-}

src/SharpCompress/Common/Dmg/Headers/GptPartitionEntry.cs

@@ -1,36 +0,0 @@
-using System;
-using System.IO;
-
-namespace SharpCompress.Common.Dmg.Headers
-{
-    internal sealed class GptPartitionEntry : GptStructBase
-    {
-        public Guid TypeGuid { get; }
-        public Guid Guid { get; }
-        public ulong FirstLba { get; }
-        public ulong LastLba { get; }
-        public ulong Attributes { get; }
-        public string Name { get; }
-
-        private GptPartitionEntry(Guid typeGuid, Guid guid, ulong firstLba, ulong lastLba, ulong attributes, string name)
-        {
-            TypeGuid = typeGuid;
-            Guid = guid;
-            FirstLba = firstLba;
-            LastLba = lastLba;
-            Attributes = attributes;
-            Name = name;
-        }
-
-        public static GptPartitionEntry Read(Stream stream)
-        {
-            return new GptPartitionEntry(
-                ReadGuid(stream),
-                ReadGuid(stream),
-                ReadUInt64(stream),
-                ReadUInt64(stream),
-                ReadUInt64(stream),
-                ReadString(stream, 72));
-        }
-    }
-}

src/SharpCompress/Common/Dmg/Headers/GptStructBase.cs

@@ -1,56 +0,0 @@
-using System;
-using System.Buffers.Binary;
-using System.IO;
-using System.Text;
-
-namespace SharpCompress.Common.Dmg.Headers
-{
-    internal abstract class GptStructBase
-    {
-        private static readonly byte[] _buffer = new byte[8];
-
-        protected static ushort ReadUInt16(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(ushort)) != sizeof(ushort))
-                throw new EndOfStreamException();
-
-            return BinaryPrimitives.ReadUInt16LittleEndian(_buffer);
-        }
-
-        protected static uint ReadUInt32(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(uint)) != sizeof(uint))
-                throw new EndOfStreamException();
-
-            return BinaryPrimitives.ReadUInt32LittleEndian(_buffer);
-        }
-
-        protected static ulong ReadUInt64(Stream stream)
-        {
-            if (stream.Read(_buffer, 0, sizeof(ulong)) != sizeof(ulong))
-                throw new EndOfStreamException();
-
-            return BinaryPrimitives.ReadUInt64LittleEndian(_buffer);
-        }
-
-        protected static Guid ReadGuid(Stream stream)
-        {
-            int a = (int)ReadUInt32(stream);
-            short b = (short)ReadUInt16(stream);
-            short c = (short)ReadUInt16(stream);
-
-            if (stream.Read(_buffer, 0, 8) != 8)
-                throw new EndOfStreamException();
-
-            return new Guid(a, b, c, _buffer);
-        }
-
-        protected static string ReadString(Stream stream, int byteSize)
-        {
-            var buffer = new byte[byteSize];
-            if (stream.Read(buffer, 0, byteSize) != byteSize)
-                throw new EndOfStreamException();
-            return Encoding.Unicode.GetString(buffer).NullTerminate();
-        }
-    }
-}

src/SharpCompress/Common/Dmg/Headers/UdifChecksum.cs

@@ -1,33 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace SharpCompress.Common.Dmg.Headers
-{
-    internal sealed class UdifChecksum : DmgStructBase
-    {
-        private const int MaxSize = 32; // * 4 to get byte size
-
-        public uint Type { get; }
-        public uint Size { get; } // in bits
-        public IReadOnlyList<uint> Bits { get; }
-
-        private UdifChecksum(uint type, uint size, IReadOnlyList<uint> bits)
-        {
-            Type = type;
-            Size = size;
-            Bits = bits;
-        }
-
-        public static UdifChecksum Read(ref ReadOnlySpan<byte> data)
-        {
-            uint type = ReadUInt32(ref data);
-            uint size = ReadUInt32(ref data);
-
-            var bits = new uint[MaxSize];
-            for (int i = 0; i < MaxSize; i++)
-                bits[i] = ReadUInt32(ref data);
-
-            return new UdifChecksum(type, size, bits);
-        }
-    }
-}

src/SharpCompress/Common/Dmg/PartitionFormat.cs

@@ -1,14 +0,0 @@
-using System;
-
-namespace SharpCompress.Common.Dmg
-{
-    internal static class PartitionFormat
-    {
-        public static readonly Guid AppleHFS         = new Guid("48465300-0000-11AA-AA11-00306543ECAC");
-        public static readonly Guid AppleUFS         = new Guid("55465300-0000-11AA-AA11-00306543ECAC");
-        public static readonly Guid AppleBoot        = new Guid("426F6F74-0000-11AA-AA11-00306543ECAC");
-        public static readonly Guid AppleRaid        = new Guid("52414944-0000-11AA-AA11-00306543ECAC");
-        public static readonly Guid AppleRaidOffline = new Guid("52414944-5F4F-11AA-AA11-00306543ECAC");
-        public static readonly Guid AppleLabel       = new Guid("4C616265-6C00-11AA-AA11-00306543ECAC");
-    }
-}

src/SharpCompress/Common/ExtractionMethods.cs

@@ -14,14 +14,25 @@ namespace SharpCompress.Common
                                                  Action<string, ExtractionOptions?> write)
         {
             string destinationFileName;
-            string file = Path.GetFileName(entry.Key);
             string fullDestinationDirectoryPath = Path.GetFullPath(destinationDirectory);
 
+            //check for trailing slash.
+            if (fullDestinationDirectoryPath[fullDestinationDirectoryPath.Length - 1] != Path.DirectorySeparatorChar)
+            {
+                fullDestinationDirectoryPath += Path.DirectorySeparatorChar;
+            }
+
+            if (!Directory.Exists(fullDestinationDirectoryPath))
+            {
+                throw new ExtractionException($"Directory does not exist to extract to: {fullDestinationDirectoryPath}");
+            }
+
             options ??= new ExtractionOptions()
             {
                 Overwrite = true
             };
 
+            string file = Path.GetFileName(entry.Key);
             if (options.ExtractFullPath)
             {
                 string folder = Path.GetDirectoryName(entry.Key)!;

src/SharpCompress/Common/IncompleteArchiveException.cs

@@ -1,6 +1,4 @@
-using System;
-
-namespace SharpCompress.Common
+namespace SharpCompress.Common
 {
     public class IncompleteArchiveException : ArchiveException
     {
@@ -8,10 +6,5 @@ namespace SharpCompress.Common
             : base(message)
         {
         }
-
-        public IncompleteArchiveException(string message, Exception inner)
-            : base(message, inner)
-        {
-        }
     }
 }

src/SharpCompress/Common/ZStandard/ZStandardEntry.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using SharpCompress.Common.GZip;
+
+namespace SharpCompress.Common.ZStandard
+{
+    public class ZStandardEntry : Entry
+    {
+        private readonly ZStandardFilePart _filePart;
+
+        internal ZStandardEntry(ZStandardFilePart filePart)
+        {
+            _filePart = filePart;
+        }
+
+        public override CompressionType CompressionType => CompressionType.GZip;
+
+        public override long Crc => _filePart.Crc ?? 0;
+
+        public override string Key => _filePart.FilePartName;
+
+        public override string? LinkTarget => null;
+
+        public override long CompressedSize => 0;
+
+        public override long Size => _filePart.UncompressedSize ?? 0;
+
+        public override DateTime? LastModifiedTime => _filePart.DateModified;
+
+        public override DateTime? CreatedTime => null;
+
+        public override DateTime? LastAccessedTime => null;
+
+        public override DateTime? ArchivedTime => null;
+
+        public override bool IsEncrypted => false;
+
+        public override bool IsDirectory => false;
+
+        public override bool IsSplitAfter => false;
+
+        internal override IEnumerable<FilePart> Parts => _filePart.AsEnumerable<FilePart>();
+
+        internal static IEnumerable<GZipEntry> GetEntries(Stream stream, OptionsBase options)
+        {
+            yield return new GZipEntry(new GZipFilePart(stream, options.ArchiveEncoding));
+        }
+    }
+}

src/SharpCompress/Common/ZStandard/ZStandardFilePart.cs

@@ -0,0 +1,37 @@
+using System;
+using System.IO;
+using ZstdSharp;
+
+namespace SharpCompress.Common.ZStandard
+{
+    internal sealed class ZStandardFilePart : FilePart
+    {
+        private string _name = "";
+        private readonly Stream _stream;
+
+        internal ZStandardFilePart(Stream stream, ArchiveEncoding archiveEncoding)
+            : base(archiveEncoding)
+        {
+            _stream = stream;
+            EntryStartPosition = stream.Position;
+        }
+
+        internal long EntryStartPosition { get; }
+
+        internal DateTime? DateModified { get; private set; }
+        internal int? Crc { get; private set; }
+        internal int? UncompressedSize { get; private set; }
+
+        internal override string FilePartName => _name!;
+
+        internal override Stream GetCompressedStream()
+        {
+            return new DecompressionStream(_stream);
+        }
+
+        internal override Stream GetRawStream()
+        {
+            return _stream;
+        }
+    }
+}

src/SharpCompress/Common/ZStandard/ZStandardVolume.cs

@@ -0,0 +1,23 @@
+using System.IO;
+using SharpCompress.Readers;
+
+namespace SharpCompress.Common.ZStandard
+{
+    public class ZStandardVolume : Volume
+    {
+        public ZStandardVolume(Stream stream, ReaderOptions options)
+            : base(stream, options)
+        {
+        }
+
+        public ZStandardVolume(FileInfo fileInfo, ReaderOptions options)
+            : base(fileInfo.OpenRead(), options)
+        {
+            options.LeaveStreamOpen = false;
+        }
+
+        public override bool IsFirstVolume => true;
+
+        public override bool IsMultiVolume => true;
+    }
+}

src/SharpCompress/Common/Zip/SeekableZipHeaderFactory.cs

@@ -36,7 +36,7 @@ namespace SharpCompress.Common.Zip
                 // ZIP64_END_OF_CENTRAL_DIRECTORY_LOCATOR should be before the EOCD
                 stream.Seek(eocd_location - ZIP64_EOCD_LENGTH - 4, SeekOrigin.Begin);
                 uint zip64_locator = reader.ReadUInt32();
-                if( zip64_locator != ZIP64_END_OF_CENTRAL_DIRECTORY_LOCATOR )
+                if (zip64_locator != ZIP64_END_OF_CENTRAL_DIRECTORY_LOCATOR)
                 {
                     throw new ArchiveException("Failed to locate the Zip64 Directory Locator");
                 }
@@ -86,11 +86,11 @@ namespace SharpCompress.Common.Zip
             }
         }
 
-        private static bool IsMatch( byte[] haystack, int position, byte[] needle)
+        private static bool IsMatch(byte[] haystack, int position, byte[] needle)
         {
-            for( int i = 0; i < needle.Length; i++ )
+            for (int i = 0; i < needle.Length; i++)
             {
-                if( haystack[ position + i ] != needle[ i ] )
+                if (haystack[position + i] != needle[i])
                 {
                     return false;
                 }
@@ -117,11 +117,12 @@ namespace SharpCompress.Common.Zip
             // Search in reverse
             Array.Reverse(seek);
 
-            var max_search_area = len - MINIMUM_EOCD_LENGTH;
+            // don't exclude the minimum eocd region, otherwise you fail to locate the header in empty zip files
+            var max_search_area = len; // - MINIMUM_EOCD_LENGTH;
 
-            for( int pos_from_end = 0; pos_from_end < max_search_area; ++pos_from_end)
+            for (int pos_from_end = 0; pos_from_end < max_search_area; ++pos_from_end)
             {
-                if( IsMatch(seek, pos_from_end, needle) )
+                if (IsMatch(seek, pos_from_end, needle))
                 {
                     stream.Seek(-pos_from_end, SeekOrigin.End);
                     return;

src/SharpCompress/Compressors/BZip2/BZip2Stream.cs

@@ -83,7 +83,7 @@ namespace SharpCompress.Compressors.BZip2
             stream.SetLength(value);
         }
 
-#if !NET461 && !NETSTANDARD2_0
+#if !NETFRAMEWORK && !NETSTANDARD2_0
 
         public override int Read(Span<byte> buffer)
         {
@@ -123,4 +123,4 @@ namespace SharpCompress.Compressors.BZip2
             return true;
         }
     }
-}
+}

src/SharpCompress/Compressors/Deflate/ZlibBaseStream.cs

@@ -502,13 +502,37 @@ namespace SharpCompress.Compressors.Deflate
                 throw new ZlibException("Cannot Read after Writing.");
             }
 
+            int rc = 0;
+
+            // set up the output of the deflate/inflate codec:
+            _z.OutputBuffer = buffer;
+            _z.NextOut = offset;
+            _z.AvailableBytesOut = count;
+
             if (count == 0)
             {
                 return 0;
             }
             if (nomoreinput && _wantCompress)
             {
-                return 0; // workitem 8557
+                // no more input data available; therefore we flush to
+                // try to complete the read
+                rc = _z.Deflate(FlushType.Finish);
+
+                if (rc != ZlibConstants.Z_OK && rc != ZlibConstants.Z_STREAM_END)
+                {
+                    throw new ZlibException(String.Format("Deflating:  rc={0}  msg={1}", rc, _z.Message));
+                }
+
+                rc = (count - _z.AvailableBytesOut);
+
+                // calculate CRC after reading
+                if (crc != null)
+                {
+                    crc.SlurpBlock(buffer, offset, rc);
+                }
+
+                return rc;
             }
             if (buffer is null)
             {
@@ -527,13 +551,6 @@ namespace SharpCompress.Compressors.Deflate
                 throw new ArgumentOutOfRangeException(nameof(count));
             }
 
-            int rc = 0;
-
-            // set up the output of the deflate/inflate codec:
-            _z.OutputBuffer = buffer;
-            _z.NextOut = offset;
-            _z.AvailableBytesOut = count;
-
             // This is necessary in case _workingBuffer has been resized. (new byte[])
             // (The first reference to _workingBuffer goes through the private accessor which
             // may initialize it.)

src/SharpCompress/Compressors/LZMA/LZipStream.cs

@@ -118,7 +118,7 @@ namespace SharpCompress.Compressors.LZMA
         public override void SetLength(long value) => throw new NotImplementedException();
 
 
-#if !NET461 && !NETSTANDARD2_0
+#if !NETFRAMEWORK && !NETSTANDARD2_0
 
         public override int Read(Span<byte> buffer)
         {

src/SharpCompress/Compressors/Zstd/CompressionStream.cs

@@ -0,0 +1,201 @@
+using System;
+using System.Buffers;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using ZstdSharp.Unsafe;
+
+namespace ZstdSharp
+{
+    public class CompressionStream : Stream
+    {
+        private readonly Stream innerStream;
+        private readonly byte[] outputBuffer;
+        private Compressor compressor;
+        private ZSTD_outBuffer_s output;
+
+        public CompressionStream(Stream stream, int level = Compressor.DefaultCompressionLevel,
+            int bufferSize = 0)
+        {
+            if (stream == null)
+                throw new ArgumentNullException(nameof(stream));
+
+            if (!stream.CanWrite)
+                throw new ArgumentException("Stream is not writable", nameof(stream));
+
+            if (bufferSize < 0)
+                throw new ArgumentOutOfRangeException(nameof(bufferSize));
+
+            innerStream = stream;
+            compressor = new Compressor(level);
+
+            var outputBufferSize =
+                bufferSize > 0 ? bufferSize : (int) Methods.ZSTD_CStreamOutSize().EnsureZstdSuccess();
+            outputBuffer = ArrayPool<byte>.Shared.Rent(outputBufferSize);
+            output = new ZSTD_outBuffer_s {pos = 0, size = (nuint) outputBufferSize};
+        }
+
+        public void SetParameter(ZSTD_cParameter parameter, int value)
+        {
+            EnsureNotDisposed();
+            compressor.SetParameter(parameter, value);
+        }
+
+        public int GetParameter(ZSTD_cParameter parameter)
+        {
+            EnsureNotDisposed();
+            return compressor.GetParameter(parameter);
+        }
+
+        public void LoadDictionary(byte[] dict)
+        {
+            EnsureNotDisposed();
+            compressor.LoadDictionary(dict);
+        }
+
+        ~CompressionStream() => Dispose(false);
+
+#if !NETSTANDARD2_0 && !NET461
+        public override async ValueTask DisposeAsync()
+#else
+        public async ValueTask DisposeAsync()
+#endif
+        {
+            if (compressor == null)
+                return;
+
+            try
+            {
+                await FlushAsync().ConfigureAwait(false);
+            }
+            finally
+            {
+                ReleaseUnmanagedResources();
+                GC.SuppressFinalize(this);
+            }
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            if (compressor == null)
+                return;
+
+            try
+            {
+                if (disposing)
+                    Flush();
+            }
+            finally
+            {
+                ReleaseUnmanagedResources();
+            }
+        }
+
+        private void ReleaseUnmanagedResources()
+        {
+            compressor.Dispose();
+            ArrayPool<byte>.Shared.Return(outputBuffer);
+        }
+
+        public override void Flush() 
+            => WriteInternal(null, true);
+
+        public override async Task FlushAsync(CancellationToken cancellationToken)
+            => await WriteInternalAsync(null, true, cancellationToken).ConfigureAwait(false);
+
+        public override void Write(byte[] buffer, int offset, int count)
+            => Write(new ReadOnlySpan<byte>(buffer, offset, count));
+
+#if !NETSTANDARD2_0 && !NET461
+        public override void Write(ReadOnlySpan<byte> buffer)
+            => WriteInternal(buffer, false);
+#else
+        public void Write(ReadOnlySpan<byte> buffer)
+            => WriteInternal(buffer, false);
+#endif
+
+        private void WriteInternal(ReadOnlySpan<byte> buffer, bool lastChunk)
+        {
+            EnsureNotDisposed();
+
+            var input = new ZSTD_inBuffer_s {pos = 0, size = buffer != null ? (nuint) buffer.Length : 0};
+            nuint remaining;
+            do
+            {
+                output.pos = 0;
+                remaining = CompressStream(ref input, buffer,
+                    lastChunk ? ZSTD_EndDirective.ZSTD_e_end : ZSTD_EndDirective.ZSTD_e_continue);
+
+                var written = (int) output.pos;
+                if (written > 0)
+                    innerStream.Write(outputBuffer, 0, written);
+            } while (lastChunk ? remaining > 0 : input.pos < input.size);
+        }
+
+        private async ValueTask WriteInternalAsync(ReadOnlyMemory<byte>? buffer, bool lastChunk,
+            CancellationToken cancellationToken = default)
+        {
+            EnsureNotDisposed();
+
+            var input = new ZSTD_inBuffer_s { pos = 0, size = buffer.HasValue ? (nuint)buffer.Value.Length : 0 };
+            nuint remaining;
+            do
+            {
+                output.pos = 0;
+                remaining = CompressStream(ref input, buffer.HasValue ? buffer.Value.Span : null,
+                    lastChunk ? ZSTD_EndDirective.ZSTD_e_end : ZSTD_EndDirective.ZSTD_e_continue);
+
+                var written = (int) output.pos;
+                if (written > 0)
+                    await innerStream.WriteAsync(outputBuffer, 0, written, cancellationToken).ConfigureAwait(false);
+            } while (lastChunk ? remaining > 0 : input.pos < input.size);
+        }
+
+        public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+            => WriteAsync(new ReadOnlyMemory<byte>(buffer, offset, count), cancellationToken).AsTask();
+
+#if !NETSTANDARD2_0 && !NET461
+        public override async ValueTask WriteAsync(ReadOnlyMemory<byte> buffer,
+            CancellationToken cancellationToken = default)
+            => await WriteInternalAsync(buffer, false, cancellationToken).ConfigureAwait(false);
+#else
+        public async ValueTask WriteAsync(ReadOnlyMemory<byte> buffer,
+            CancellationToken cancellationToken = default)
+            => await WriteInternalAsync(buffer, false, cancellationToken).ConfigureAwait(false);
+#endif
+
+        internal unsafe nuint CompressStream(ref ZSTD_inBuffer_s input, ReadOnlySpan<byte> inputBuffer,
+            ZSTD_EndDirective directive)
+        {
+            fixed (byte* inputBufferPtr = inputBuffer)
+            fixed (byte* outputBufferPtr = outputBuffer)
+            {
+                input.src = inputBufferPtr;
+                output.dst = outputBufferPtr;
+                return compressor.CompressStream(ref input, ref output, directive).EnsureZstdSuccess();
+            }
+        }
+
+        public override bool CanRead => false;
+        public override bool CanSeek => false;
+        public override bool CanWrite => true;
+
+        public override long Length => throw new NotSupportedException();
+
+        public override long Position
+        {
+            get => throw new NotSupportedException();
+            set => throw new NotSupportedException();
+        }
+
+        public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
+        public override void SetLength(long value) => throw new NotSupportedException();
+        public override int Read(byte[] buffer, int offset, int count) => throw new NotSupportedException();
+
+        private void EnsureNotDisposed()
+        {
+            if (compressor == null)
+                throw new ObjectDisposedException(nameof(CompressionStream));
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Compressor.cs

@@ -0,0 +1,164 @@
+using System;
+using ZstdSharp.Unsafe;
+
+namespace ZstdSharp
+{
+    public unsafe class Compressor : IDisposable
+    {
+        public static int MinCompressionLevel => Methods.ZSTD_minCLevel();
+        public static int MaxCompressionLevel => Methods.ZSTD_maxCLevel();
+        public const int DefaultCompressionLevel = 0;
+
+        private int level = DefaultCompressionLevel;
+
+        private ZSTD_CCtx_s* cctx;
+
+        public int Level
+        {
+            get => level;
+            set
+            {
+                if (level != value)
+                {
+                    level = value;
+                    SetParameter(ZSTD_cParameter.ZSTD_c_compressionLevel, value);
+                }
+            }
+        }
+
+        public void SetParameter(ZSTD_cParameter parameter, int value)
+        {
+            EnsureNotDisposed();
+            Methods.ZSTD_CCtx_setParameter(cctx, parameter, value).EnsureZstdSuccess();
+        }
+
+        public int GetParameter(ZSTD_cParameter parameter)
+        {
+            EnsureNotDisposed();
+            int value;
+            Methods.ZSTD_CCtx_getParameter(cctx, parameter, &value).EnsureZstdSuccess();
+            return value;
+        }
+
+        public void LoadDictionary(byte[] dict)
+        {
+            EnsureNotDisposed();
+            if (dict == null)
+            {
+                Methods.ZSTD_CCtx_loadDictionary(cctx, null, 0).EnsureZstdSuccess();
+            }
+            else
+            {
+
+                fixed (byte* dictPtr = dict)
+                    Methods.ZSTD_CCtx_loadDictionary(cctx, dictPtr, (nuint) dict.Length).EnsureZstdSuccess();
+            }
+        }
+
+        public Compressor(int level = DefaultCompressionLevel)
+        {
+            cctx = Methods.ZSTD_createCCtx();
+            if (cctx == null)
+                throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_GENERIC, "Failed to create cctx");
+
+            Level = level;
+        }
+
+        ~Compressor()
+        {
+            ReleaseUnmanagedResources();
+        }
+
+        public static int GetCompressBound(int length) 
+            => (int) Methods.ZSTD_compressBound((nuint) length);
+
+        public static ulong GetCompressBoundLong(ulong length)
+            => Methods.ZSTD_compressBound((nuint) length);
+
+        public Span<byte> Wrap(ReadOnlySpan<byte> src)
+        {
+            var dest = new byte[GetCompressBound(src.Length)];
+            var length = Wrap(src, dest);
+            return new Span<byte>(dest, 0, length);
+        }
+
+        public int Wrap(byte[] src, byte[] dest, int offset)
+            => Wrap(src, new Span<byte>(dest, offset, dest.Length - offset));
+
+        public int Wrap(ReadOnlySpan<byte> src, Span<byte> dest)
+        {
+            EnsureNotDisposed();
+            fixed (byte* srcPtr = src)
+            fixed (byte* destPtr = dest)
+                return (int) Methods
+                    .ZSTD_compress2(cctx, destPtr, (nuint) dest.Length, srcPtr, (nuint) src.Length)
+                    .EnsureZstdSuccess();
+        }
+
+        public int Wrap(ArraySegment<byte> src, ArraySegment<byte> dest) 
+            => Wrap((ReadOnlySpan<byte>) src, dest);
+
+        public int Wrap(byte[] src, int srcOffset, int srcLength, byte[] dst, int dstOffset, int dstLength) 
+            => Wrap(new ReadOnlySpan<byte>(src, srcOffset, srcLength), new Span<byte>(dst, dstOffset, dstLength));
+
+        public bool TryWrap(byte[] src, byte[] dest, int offset, out int written)
+            => TryWrap(src, new Span<byte>(dest, offset, dest.Length - offset), out written);
+
+        public bool TryWrap(ReadOnlySpan<byte> src, Span<byte> dest, out int written)
+        {
+            EnsureNotDisposed();
+            fixed (byte* srcPtr = src)
+            fixed (byte* destPtr = dest)
+            {
+                var returnValue =
+                    Methods.ZSTD_compress2(cctx, destPtr, (nuint) dest.Length, srcPtr, (nuint) src.Length);
+
+                if (returnValue == unchecked(0 - (nuint)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall))
+                {
+                    written = default;
+                    return false;
+                }
+
+                returnValue.EnsureZstdSuccess();
+                written = (int) returnValue;
+                return true;
+            }
+        }
+
+        public bool TryWrap(ArraySegment<byte> src, ArraySegment<byte> dest, out int written)
+            => TryWrap((ReadOnlySpan<byte>)src, dest, out written);
+
+        public bool TryWrap(byte[] src, int srcOffset, int srcLength, byte[] dst, int dstOffset, int dstLength, out int written)
+            => TryWrap(new ReadOnlySpan<byte>(src, srcOffset, srcLength), new Span<byte>(dst, dstOffset, dstLength), out written);
+
+        private void ReleaseUnmanagedResources()
+        {
+            if (cctx != null)
+            {
+                Methods.ZSTD_freeCCtx(cctx);
+                cctx = null;
+            }
+        }
+
+        public void Dispose()
+        {
+            ReleaseUnmanagedResources();
+            GC.SuppressFinalize(this);
+        }
+
+        private void EnsureNotDisposed()
+        {
+            if (cctx == null)
+                throw new ObjectDisposedException(nameof(Compressor));
+        }
+
+        internal nuint CompressStream(ref ZSTD_inBuffer_s input, ref ZSTD_outBuffer_s output, ZSTD_EndDirective directive)
+        {
+            fixed (ZSTD_inBuffer_s* inputPtr = &input)
+            fixed (ZSTD_outBuffer_s* outputPtr = &output)
+            {
+                return Methods.ZSTD_compressStream2(cctx, outputPtr, inputPtr, directive).EnsureZstdSuccess();
+            }
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Constants.cs

@@ -0,0 +1,9 @@
+namespace ZstdSharp
+{
+	internal class Constants
+	{
+		//NOTE: https://docs.microsoft.com/en-us/dotnet/framework/configure-apps/file-schema/runtime/gcallowverylargeobjects-element#remarks
+		//NOTE: https://github.com/dotnet/runtime/blob/v5.0.0-rtm.20519.4/src/libraries/System.Private.CoreLib/src/System/Array.cs#L27
+		public const ulong MaxByteArrayLength = 0x7FFFFFC7;
+	}
+}

src/SharpCompress/Compressors/Zstd/DecompressionStream.cs

@@ -0,0 +1,190 @@
+using System;
+using System.Buffers;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using ZstdSharp.Unsafe;
+
+namespace ZstdSharp
+{
+    public class DecompressionStream : Stream
+    {
+        private readonly Stream innerStream;
+        private readonly byte[] inputBuffer;
+        private readonly int inputBufferSize;
+        private Decompressor decompressor;
+        private ZSTD_inBuffer_s input;
+        private nuint lastDecompressResult = 0;
+
+        public DecompressionStream(Stream stream, int bufferSize = 0)
+        {
+            if (stream == null)
+                throw new ArgumentNullException(nameof(stream));
+
+            if (!stream.CanRead)
+                throw new ArgumentException("Stream is not readable", nameof(stream));
+
+            if (bufferSize < 0)
+                throw new ArgumentOutOfRangeException(nameof(bufferSize));
+
+            innerStream = stream;
+            decompressor = new Decompressor();
+
+            inputBufferSize = bufferSize > 0 ? bufferSize : (int) Methods.ZSTD_CStreamInSize().EnsureZstdSuccess();
+            inputBuffer = ArrayPool<byte>.Shared.Rent(inputBufferSize);
+            input = new ZSTD_inBuffer_s {pos = (nuint) inputBufferSize, size = (nuint) inputBufferSize};
+        }
+
+        public void SetParameter(ZSTD_dParameter parameter, int value)
+        {
+            EnsureNotDisposed();
+            decompressor.SetParameter(parameter, value);
+        }
+
+        public int GetParameter(ZSTD_dParameter parameter)
+        {
+            EnsureNotDisposed();
+            return decompressor.GetParameter(parameter);
+        }
+
+        public void LoadDictionary(byte[] dict)
+        {
+            EnsureNotDisposed();
+            decompressor.LoadDictionary(dict);
+        }
+
+        ~DecompressionStream() => Dispose(false);
+
+        protected override void Dispose(bool disposing)
+        {
+            if (decompressor == null)
+                return;
+
+            decompressor.Dispose();
+            ArrayPool<byte>.Shared.Return(inputBuffer);
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+            => Read(new Span<byte>(buffer, offset, count));
+
+#if !NETSTANDARD2_0 && !NETFRAMEWORK
+        public override int Read(Span<byte> buffer)
+#else
+        public int Read(Span<byte> buffer)
+#endif
+        {
+            EnsureNotDisposed();
+
+            var output = new ZSTD_outBuffer_s {pos = 0, size = (nuint) buffer.Length};
+            while (output.pos < output.size)
+            {
+                if (input.pos >= input.size)
+                {
+                    int bytesRead;
+                    if ((bytesRead = innerStream.Read(inputBuffer, 0, inputBufferSize)) == 0)
+                    {
+                        if (lastDecompressResult != 0)
+                            throw new EndOfStreamException("Premature end of stream");
+
+                        break;
+                    }
+
+                    input.size = (nuint) bytesRead;
+                    input.pos = 0;
+                }
+
+                lastDecompressResult = DecompressStream(ref output, buffer);
+            }
+
+            return (int) output.pos;
+        }
+
+        public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+            => ReadAsync(new Memory<byte>(buffer, offset, count), cancellationToken).AsTask();
+
+#if !NETSTANDARD2_0 && !NET461
+        public override async ValueTask<int> ReadAsync(Memory<byte> buffer,
+            CancellationToken cancellationToken = default)
+#else
+        public async ValueTask<int> ReadAsync(Memory<byte> buffer,
+            CancellationToken cancellationToken = default)
+#endif
+        {
+            EnsureNotDisposed();
+
+            var output = new ZSTD_outBuffer_s { pos = 0, size = (nuint)buffer.Length};
+            while (output.pos < output.size)
+            {
+                if (input.pos >= input.size)
+                {
+                    int bytesRead;
+                    if ((bytesRead = await innerStream.ReadAsync(inputBuffer, 0, inputBufferSize, cancellationToken)
+                        .ConfigureAwait(false)) == 0)
+                    {
+                        if (lastDecompressResult != 0)
+                            throw new EndOfStreamException("Premature end of stream");
+
+                        break;
+                    }
+
+                    input.size = (nuint) bytesRead;
+                    input.pos = 0;
+                }
+
+                lastDecompressResult = DecompressStream(ref output, buffer.Span);
+            }
+
+            return (int) output.pos;
+        }
+
+        private unsafe nuint DecompressStream(ref ZSTD_outBuffer_s output, Span<byte> outputBuffer)
+        {
+            fixed (byte* inputBufferPtr = inputBuffer)
+            fixed (byte* outputBufferPtr = outputBuffer)
+            {
+                input.src = inputBufferPtr;
+                output.dst = outputBufferPtr;
+                return decompressor.DecompressStream(ref input, ref output);
+            }
+        }
+
+        public override bool CanRead => true;
+        public override bool CanSeek => false;
+        public override bool CanWrite => false;
+
+        public override long Length => throw new NotSupportedException();
+
+        public override long Position
+        {
+            get => throw new NotSupportedException();
+            set => throw new NotSupportedException();
+        }
+
+        public override void Flush() => throw new NotSupportedException();
+
+        public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
+        public override void SetLength(long value) => throw new NotSupportedException();
+        public override void Write(byte[] buffer, int offset, int count) => throw new NotSupportedException();
+
+        private void EnsureNotDisposed()
+        {
+            if (decompressor == null)
+                throw new ObjectDisposedException(nameof(DecompressionStream));
+        }
+
+#if NETSTANDARD2_0 || NET461
+        public virtual ValueTask DisposeAsync()
+        {
+            try
+            {
+                Dispose();
+                return default;
+            }
+            catch (Exception exc)
+            {
+                return new ValueTask(Task.FromException(exc));
+            }
+        }
+#endif
+    }
+}

src/SharpCompress/Compressors/Zstd/Decompressor.cs

@@ -0,0 +1,149 @@
+using System;
+using ZstdSharp.Unsafe;
+
+namespace ZstdSharp
+{
+    public unsafe class Decompressor : IDisposable
+    {
+        private ZSTD_DCtx_s* dctx;
+
+        public Decompressor()
+        {
+            dctx = Methods.ZSTD_createDCtx();
+            if (dctx == null)
+                throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_GENERIC, "Failed to create dctx");
+        }
+
+        ~Decompressor()
+        {
+            ReleaseUnmanagedResources();
+        }
+
+        public void SetParameter(ZSTD_dParameter parameter, int value)
+        {
+            EnsureNotDisposed();
+            Methods.ZSTD_DCtx_setParameter(dctx, parameter, value).EnsureZstdSuccess();
+        }
+
+        public int GetParameter(ZSTD_dParameter parameter)
+        {
+            EnsureNotDisposed();
+            int value;
+            Methods.ZSTD_DCtx_getParameter(dctx, parameter, &value).EnsureZstdSuccess();
+            return value;
+        }
+
+        public void LoadDictionary(byte[] dict)
+        {
+            EnsureNotDisposed();
+            if (dict == null)
+            {
+                Methods.ZSTD_DCtx_loadDictionary(dctx, null, 0).EnsureZstdSuccess();
+            }
+            else
+            {
+                fixed (byte* dictPtr = dict)
+                    Methods.ZSTD_DCtx_loadDictionary(dctx, dictPtr, (nuint) dict.Length).EnsureZstdSuccess();
+            }
+        }
+
+        public static ulong GetDecompressedSize(ReadOnlySpan<byte> src)
+        {
+            fixed (byte* srcPtr = src)
+                return Methods.ZSTD_decompressBound(srcPtr, (nuint) src.Length).EnsureContentSizeOk();
+        }
+
+        public static ulong GetDecompressedSize(ArraySegment<byte> src)
+            => GetDecompressedSize((ReadOnlySpan<byte>) src);
+
+        public static ulong GetDecompressedSize(byte[] src, int srcOffset, int srcLength)
+            => GetDecompressedSize(new ReadOnlySpan<byte>(src, srcOffset, srcLength));
+
+        public Span<byte> Unwrap(ReadOnlySpan<byte> src, int maxDecompressedSize = int.MaxValue)
+        {
+            var expectedDstSize = GetDecompressedSize(src);
+            if (expectedDstSize > (ulong) maxDecompressedSize)
+                throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall,
+                    $"Decompressed content size {expectedDstSize} is greater than {nameof(maxDecompressedSize)} {maxDecompressedSize}");
+            if (expectedDstSize > Constants.MaxByteArrayLength)
+                throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall,
+                    $"Decompressed content size {expectedDstSize} is greater than max possible byte array size {Constants.MaxByteArrayLength}");
+
+            var dest = new byte[expectedDstSize];
+            var length = Unwrap(src, dest);
+            return new Span<byte>(dest, 0, length);
+        }
+
+        public int Unwrap(byte[] src, byte[] dest, int offset) 
+            => Unwrap(src, new Span<byte>(dest, offset, dest.Length - offset));
+
+        public int Unwrap(ReadOnlySpan<byte> src, Span<byte> dest)
+        {
+            EnsureNotDisposed();
+            fixed (byte* srcPtr = src)
+            fixed (byte* destPtr = dest)
+                return (int) Methods
+                    .ZSTD_decompressDCtx(dctx, destPtr, (nuint) dest.Length, srcPtr, (nuint) src.Length)
+                    .EnsureZstdSuccess();
+        }
+
+        public int Unwrap(byte[] src, int srcOffset, int srcLength, byte[] dst, int dstOffset, int dstLength)
+            => Unwrap(new ReadOnlySpan<byte>(src, srcOffset, srcLength), new Span<byte>(dst, dstOffset, dstLength));
+
+        public bool TryUnwrap(byte[] src, byte[] dest, int offset, out int written)
+            => TryUnwrap(src, new Span<byte>(dest, offset, dest.Length - offset), out written);
+
+        public bool TryUnwrap(ReadOnlySpan<byte> src, Span<byte> dest, out int written)
+        {
+            EnsureNotDisposed();
+            fixed (byte* srcPtr = src)
+            fixed (byte* destPtr = dest)
+            {
+                var returnValue =
+                    Methods.ZSTD_decompressDCtx(dctx, destPtr, (nuint) dest.Length, srcPtr, (nuint) src.Length);
+
+                if (returnValue == unchecked(0 - (nuint)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall))
+                {
+                    written = default;
+                    return false;
+                }
+
+                returnValue.EnsureZstdSuccess();
+                written = (int) returnValue;
+                return true;
+            }
+        }
+
+        public bool TryUnwrap(byte[] src, int srcOffset, int srcLength, byte[] dst, int dstOffset, int dstLength, out int written)
+            => TryUnwrap(new ReadOnlySpan<byte>(src, srcOffset, srcLength), new Span<byte>(dst, dstOffset, dstLength), out written);
+
+        private void ReleaseUnmanagedResources()
+        {
+            if (dctx != null)
+            {
+                Methods.ZSTD_freeDCtx(dctx);
+                dctx = null;
+            }
+        }
+
+        public void Dispose()
+        {
+            ReleaseUnmanagedResources();
+            GC.SuppressFinalize(this);
+        }
+        private void EnsureNotDisposed()
+        {
+            if (dctx == null)
+                throw new ObjectDisposedException(nameof(Decompressor));
+        }
+
+        internal nuint DecompressStream(ref ZSTD_inBuffer_s input, ref ZSTD_outBuffer_s output)
+        {
+            fixed (ZSTD_inBuffer_s* inputPtr = &input)
+            fixed (ZSTD_outBuffer_s* outputPtr = &output)
+            {
+                return Methods.ZSTD_decompressStream(dctx, outputPtr, inputPtr).EnsureZstdSuccess();
+            }
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/DictBuilder.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using ZstdSharp.Unsafe;
+
+namespace ZstdSharp
+{
+    public static unsafe class DictBuilder
+    {
+        public static byte[] TrainFromBuffer(IEnumerable<byte[]> samples, int dictCapacity = DefaultDictCapacity)
+        {
+            var ms = new MemoryStream();
+            var samplesSizes = samples.Select(sample =>
+            {
+                ms.Write(sample, 0, sample.Length);
+                return (nuint) sample.Length;
+            }).ToArray();
+
+            var dictBuffer = new byte[dictCapacity];
+            fixed (byte* dictBufferPtr = dictBuffer)
+            fixed (byte* samplesBufferPtr = ms.GetBuffer())
+            fixed (nuint* samplesSizesPtr = samplesSizes)
+            {
+                var dictSize = (int) Methods
+                    .ZDICT_trainFromBuffer(dictBufferPtr, (nuint) dictCapacity, samplesBufferPtr, samplesSizesPtr,
+                        (uint) samplesSizes.Length)
+                    .EnsureZdictSuccess();
+
+                if (dictCapacity != dictSize)
+                    Array.Resize(ref dictBuffer, dictSize);
+
+                return dictBuffer;
+            }
+        }
+
+        public const int DefaultDictCapacity = 112640; // Used by zstd utility by default
+    }
+}

src/SharpCompress/Compressors/Zstd/Polyfills/BitOperations.cs

@@ -0,0 +1,201 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#if !NETCOREAPP3_0_OR_GREATER
+
+using System.Runtime.CompilerServices;
+using static ZstdSharp.UnsafeHelper;
+
+// Some routines inspired by the Stanford Bit Twiddling Hacks by Sean Eron Anderson:
+// http://graphics.stanford.edu/~seander/bithacks.html
+
+namespace System.Numerics
+{
+    /// <summary>
+    /// Utility methods for intrinsic bit-twiddling operations.
+    /// The methods use hardware intrinsics when available on the underlying platform,
+    /// otherwise they use optimized software fallbacks.
+    /// </summary>
+    public static unsafe class BitOperations
+    {
+        // hack: should be public because of inline
+        public static readonly byte* TrailingZeroCountDeBruijn = GetArrayPointer(new byte[]
+        {
+            00, 01, 28, 02, 29, 14, 24, 03,
+            30, 22, 20, 15, 25, 17, 04, 08,
+            31, 27, 13, 23, 21, 19, 16, 07,
+            26, 12, 18, 06, 11, 05, 10, 09
+        });
+
+        // hack: should be public because of inline
+        public static readonly byte* Log2DeBruijn = GetArrayPointer(new byte[]
+        {
+            00, 09, 01, 10, 13, 21, 02, 29,
+            11, 14, 16, 18, 22, 25, 03, 30,
+            08, 12, 20, 28, 15, 17, 24, 07,
+            19, 27, 23, 06, 26, 05, 04, 31
+        });
+
+        /// <summary>
+        /// Returns the integer (floor) log of the specified value, base 2.
+        /// Note that by convention, input value 0 returns 0 since log(0) is undefined.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int Log2(uint value)
+        {
+            // The 0->0 contract is fulfilled by setting the LSB to 1.
+            // Log(1) is 0, and setting the LSB for values > 1 does not change the log2 result.
+            value |= 1;
+
+            // value    lzcnt   actual  expected
+            // ..0001   31      31-31    0
+            // ..0010   30      31-30    1
+            // 0010..    2      31-2    29
+            // 0100..    1      31-1    30
+            // 1000..    0      31-0    31
+
+            // Fallback contract is 0->0
+            // No AggressiveInlining due to large method size
+            // Has conventional contract 0->0 (Log(0) is undefined)
+
+            // Fill trailing zeros with ones, eg 00010010 becomes 00011111
+            value |= value >> 01;
+            value |= value >> 02;
+            value |= value >> 04;
+            value |= value >> 08;
+            value |= value >> 16;
+
+            // uint.MaxValue >> 27 is always in range [0 - 31] so we use Unsafe.AddByteOffset to avoid bounds check
+            return Log2DeBruijn[
+                // Using deBruijn sequence, k=2, n=5 (2^5=32) : 0b_0000_0111_1100_0100_1010_1100_1101_1101u
+                (int)((value * 0x07C4ACDDu) >> 27)];
+        }
+
+        /// <summary>
+        /// Returns the integer (floor) log of the specified value, base 2.
+        /// Note that by convention, input value 0 returns 0 since log(0) is undefined.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int Log2(ulong value)
+        {
+            value |= 1;
+
+            uint hi = (uint)(value >> 32);
+
+            if (hi == 0)
+            {
+                return Log2((uint)value);
+            }
+
+            return 32 + Log2(hi);
+        }
+
+        /// <summary>
+        /// Count the number of trailing zero bits in an integer value.
+        /// Similar in behavior to the x86 instruction TZCNT.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int TrailingZeroCount(int value)
+            => TrailingZeroCount((uint)value);
+
+        /// <summary>
+        /// Count the number of trailing zero bits in an integer value.
+        /// Similar in behavior to the x86 instruction TZCNT.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int TrailingZeroCount(uint value)
+        {
+            // Unguarded fallback contract is 0->0, BSF contract is 0->undefined
+            if (value == 0)
+            {
+                return 32;
+            }
+
+            // uint.MaxValue >> 27 is always in range [0 - 31] so we use Unsafe.AddByteOffset to avoid bounds check
+            return TrailingZeroCountDeBruijn[
+                // Using deBruijn sequence, k=2, n=5 (2^5=32) : 0b_0000_0111_0111_1100_1011_0101_0011_0001u
+                (int)(((value & (uint)-(int)value) * 0x077CB531u) >> 27)]; // Multi-cast mitigates redundant conv.u8
+        }
+
+        /// <summary>
+        /// Count the number of trailing zero bits in a mask.
+        /// Similar in behavior to the x86 instruction TZCNT.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int TrailingZeroCount(long value)
+            => TrailingZeroCount((ulong)value);
+
+        /// <summary>
+        /// Count the number of trailing zero bits in a mask.
+        /// Similar in behavior to the x86 instruction TZCNT.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int TrailingZeroCount(ulong value)
+        {
+            uint lo = (uint)value;
+
+            if (lo == 0)
+            {
+                return 32 + TrailingZeroCount((uint)(value >> 32));
+            }
+
+            return TrailingZeroCount(lo);
+        }
+
+        /// <summary>
+        /// Rotates the specified value left by the specified number of bits.
+        /// Similar in behavior to the x86 instruction ROL.
+        /// </summary>
+        /// <param name="value">The value to rotate.</param>
+        /// <param name="offset">The number of bits to rotate by.
+        /// Any value outside the range [0..31] is treated as congruent mod 32.</param>
+        /// <returns>The rotated value.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static uint RotateLeft(uint value, int offset)
+            => (value << offset) | (value >> (32 - offset));
+
+        /// <summary>
+        /// Rotates the specified value left by the specified number of bits.
+        /// Similar in behavior to the x86 instruction ROL.
+        /// </summary>
+        /// <param name="value">The value to rotate.</param>
+        /// <param name="offset">The number of bits to rotate by.
+        /// Any value outside the range [0..63] is treated as congruent mod 64.</param>
+        /// <returns>The rotated value.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static ulong RotateLeft(ulong value, int offset)
+            => (value << offset) | (value >> (64 - offset));
+
+        /// <summary>
+        /// Rotates the specified value right by the specified number of bits.
+        /// Similar in behavior to the x86 instruction ROR.
+        /// </summary>
+        /// <param name="value">The value to rotate.</param>
+        /// <param name="offset">The number of bits to rotate by.
+        /// Any value outside the range [0..31] is treated as congruent mod 32.</param>
+        /// <returns>The rotated value.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static uint RotateRight(uint value, int offset)
+            => (value >> offset) | (value << (32 - offset));
+
+        /// <summary>
+        /// Rotates the specified value right by the specified number of bits.
+        /// Similar in behavior to the x86 instruction ROR.
+        /// </summary>
+        /// <param name="value">The value to rotate.</param>
+        /// <param name="offset">The number of bits to rotate by.
+        /// Any value outside the range [0..63] is treated as congruent mod 64.</param>
+        /// <returns>The rotated value.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static ulong RotateRight(ulong value, int offset)
+            => (value >> offset) | (value << (64 - offset));
+    }
+}
+
+#endif

src/SharpCompress/Compressors/Zstd/Polyfills/SkipLocalsInitAttribute.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#if !NET5_0_OR_GREATER
+namespace System.Runtime.CompilerServices
+{
+    /// <summary>
+    /// Used to indicate to the compiler that the <c>.locals init</c> flag should not be set in method headers.
+    /// </summary>
+    /// <remarks>Internal copy of the .NET 5 attribute.</remarks>
+    [AttributeUsage(
+        AttributeTargets.Module |
+        AttributeTargets.Class |
+        AttributeTargets.Struct |
+        AttributeTargets.Interface |
+        AttributeTargets.Constructor |
+        AttributeTargets.Method |
+        AttributeTargets.Property |
+        AttributeTargets.Event,
+        Inherited = false)]
+    internal sealed class SkipLocalsInitAttribute : Attribute
+    {
+    }
+}
+#endif

src/SharpCompress/Compressors/Zstd/Polyfills/Vector128.cs

@@ -0,0 +1,54 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#if !NETCOREAPP3_0_OR_GREATER
+
+using System.Runtime.CompilerServices;
+
+namespace System.Runtime.Intrinsics
+{
+    public static class Vector128
+    {
+        internal const int Size = 16;
+
+        public static unsafe Vector128<byte> Create(byte value)
+        {
+            byte* pResult = stackalloc byte[16]
+            {
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+                value,
+            };
+
+            return Unsafe.AsRef<Vector128<byte>>(pResult);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Vector128<U> As<T, U>(this Vector128<T> vector)
+            where T : struct
+            where U : struct =>
+            Unsafe.As<Vector128<T>, Vector128<U>>(ref vector);
+
+        public static T GetElement<T>(this Vector128<T> vector, int index)
+            where T : struct
+        {
+            ref T e0 = ref Unsafe.As<Vector128<T>, T>(ref vector);
+            return Unsafe.Add(ref e0, index);
+        }
+    }
+}
+
+#endif

src/SharpCompress/Compressors/Zstd/Polyfills/Vector128_1.cs

@@ -0,0 +1,36 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#if !NETCOREAPP3_0_OR_GREATER
+
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace System.Runtime.Intrinsics
+{
+    [StructLayout(LayoutKind.Sequential, Size = Vector128.Size)]
+    public readonly struct Vector128<T> : IEquatable<Vector128<T>>
+        where T : struct
+    {
+        private readonly ulong _00;
+        private readonly ulong _01;
+
+        public static int Count => Vector128.Size / Unsafe.SizeOf<T>();
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public bool Equals(Vector128<T> other)
+        {
+            for (int i = 0; i < Count; i++)
+            {
+                if (!((IEquatable<T>)(this.GetElement(i))).Equals(other.GetElement(i)))
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+    }
+}
+
+#endif

src/SharpCompress/Compressors/Zstd/ThrowHelper.cs

@@ -0,0 +1,43 @@
+using ZstdSharp.Unsafe;
+
+namespace ZstdSharp
+{
+    public static unsafe class ThrowHelper
+    {
+        private const ulong ZSTD_CONTENTSIZE_UNKNOWN = unchecked(0UL - 1);
+        private const ulong ZSTD_CONTENTSIZE_ERROR = unchecked(0UL - 2);
+
+        public static nuint EnsureZstdSuccess(this nuint returnValue)
+        {
+            if (Methods.ZSTD_isError(returnValue) != 0)
+                ThrowException(returnValue, Methods.ZSTD_getErrorName(returnValue));
+
+            return returnValue;
+        }
+
+        public static nuint EnsureZdictSuccess(this nuint returnValue)
+        {
+            if (Methods.ZDICT_isError(returnValue) != 0)
+                ThrowException(returnValue, Methods.ZDICT_getErrorName(returnValue));
+
+            return returnValue;
+        }
+
+        public static ulong EnsureContentSizeOk(this ulong returnValue)
+        {
+            if (returnValue == ZSTD_CONTENTSIZE_UNKNOWN)
+                throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_GENERIC, "Decompressed content size is not specified");
+
+            if (returnValue == ZSTD_CONTENTSIZE_ERROR)
+                throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_GENERIC, "Decompressed content size cannot be determined (e.g. invalid magic number, srcSize too small)");
+
+            return returnValue;
+        }
+
+        private static void ThrowException(nuint returnValue, string message)
+        {
+            var code = 0 - returnValue;
+            throw new ZstdException((ZSTD_ErrorCode) code, message);
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/Arrays.cs

@@ -0,0 +1,368 @@
+using System;
+using static ZstdSharp.UnsafeHelper;
+
+namespace ZstdSharp.Unsafe
+{
+    public static unsafe partial class Methods
+    {
+        static uint* rtbTable = GetArrayPointer(new uint[8] {
+            0,
+            473195,
+            504333,
+            520860,
+            550000,
+            700000,
+            750000,
+            830000,
+        });
+        static byte* LL_Code = GetArrayPointer(new byte[64] 
+        {
+            0,
+            1,
+            2,
+            3,
+            4,
+            5,
+            6,
+            7,
+            8,
+            9,
+            10,
+            11,
+            12,
+            13,
+            14,
+            15,
+            16,
+            16,
+            17,
+            17,
+            18,
+            18,
+            19,
+            19,
+            20,
+            20,
+            20,
+            20,
+            21,
+            21,
+            21,
+            21,
+            22,
+            22,
+            22,
+            22,
+            22,
+            22,
+            22,
+            22,
+            23,
+            23,
+            23,
+            23,
+            23,
+            23,
+            23,
+            23,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+            24,
+        });
+        static byte* ML_Code = GetArrayPointer(new byte[128] 
+        {
+            0,
+            1,
+            2,
+            3,
+            4,
+            5,
+            6,
+            7,
+            8,
+            9,
+            10,
+            11,
+            12,
+            13,
+            14,
+            15,
+            16,
+            17,
+            18,
+            19,
+            20,
+            21,
+            22,
+            23,
+            24,
+            25,
+            26,
+            27,
+            28,
+            29,
+            30,
+            31,
+            32,
+            32,
+            33,
+            33,
+            34,
+            34,
+            35,
+            35,
+            36,
+            36,
+            36,
+            36,
+            37,
+            37,
+            37,
+            37,
+            38,
+            38,
+            38,
+            38,
+            38,
+            38,
+            38,
+            38,
+            39,
+            39,
+            39,
+            39,
+            39,
+            39,
+            39,
+            39,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            40,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            41,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+            42,
+        });
+        static ulong* srcSizeTiers = GetArrayPointer(new ulong[4] 
+        {
+            16 * (1 << 10),
+            128 * (1 << 10),
+            256 * (1 << 10),
+            (unchecked(0UL - 1)),
+        });
+        static ZSTD_blockCompressor?[][] blockCompressor = new ZSTD_blockCompressor?[4][] 
+                                                           {
+                                                               new ZSTD_blockCompressor[10]
+                                                               {
+                                                                   ZSTD_compressBlock_fast,
+                                                                   ZSTD_compressBlock_fast,
+                                                                   ZSTD_compressBlock_doubleFast,
+                                                                   ZSTD_compressBlock_greedy,
+                                                                   ZSTD_compressBlock_lazy,
+                                                                   ZSTD_compressBlock_lazy2,
+                                                                   ZSTD_compressBlock_btlazy2,
+                                                                   ZSTD_compressBlock_btopt,
+                                                                   ZSTD_compressBlock_btultra,
+                                                                   ZSTD_compressBlock_btultra2,
+                                                               },
+                                                               new ZSTD_blockCompressor[10]
+                                                               {
+                                                                   ZSTD_compressBlock_fast_extDict,
+                                                                   ZSTD_compressBlock_fast_extDict,
+                                                                   ZSTD_compressBlock_doubleFast_extDict,
+                                                                   ZSTD_compressBlock_greedy_extDict,
+                                                                   ZSTD_compressBlock_lazy_extDict,
+                                                                   ZSTD_compressBlock_lazy2_extDict,
+                                                                   ZSTD_compressBlock_btlazy2_extDict,
+                                                                   ZSTD_compressBlock_btopt_extDict,
+                                                                   ZSTD_compressBlock_btultra_extDict,
+                                                                   ZSTD_compressBlock_btultra_extDict,
+                                                               },
+                                                               new ZSTD_blockCompressor[10]
+                                                               {
+                                                                   ZSTD_compressBlock_fast_dictMatchState,
+                                                                   ZSTD_compressBlock_fast_dictMatchState,
+                                                                   ZSTD_compressBlock_doubleFast_dictMatchState,
+                                                                   ZSTD_compressBlock_greedy_dictMatchState,
+                                                                   ZSTD_compressBlock_lazy_dictMatchState,
+                                                                   ZSTD_compressBlock_lazy2_dictMatchState,
+                                                                   ZSTD_compressBlock_btlazy2_dictMatchState,
+                                                                   ZSTD_compressBlock_btopt_dictMatchState,
+                                                                   ZSTD_compressBlock_btultra_dictMatchState,
+                                                                   ZSTD_compressBlock_btultra_dictMatchState,
+                                                               },
+                                                               new ZSTD_blockCompressor?[10]
+                                                               {
+                                                                   null,
+                                                                   null,
+                                                                   null,
+                                                                   ZSTD_compressBlock_greedy_dedicatedDictSearch,
+                                                                   ZSTD_compressBlock_lazy_dedicatedDictSearch,
+                                                                   ZSTD_compressBlock_lazy2_dedicatedDictSearch,
+                                                                   null,
+                                                                   null,
+                                                                   null,
+                                                                   null,
+                                                               },
+                                                           };
+        static ZSTD_blockCompressor[][] rowBasedBlockCompressors = new ZSTD_blockCompressor[4][] 
+        {
+            new ZSTD_blockCompressor[3]
+            {
+                ZSTD_compressBlock_greedy_row,
+                ZSTD_compressBlock_lazy_row,
+                ZSTD_compressBlock_lazy2_row,
+            },
+            new ZSTD_blockCompressor[3]
+            {
+                ZSTD_compressBlock_greedy_extDict_row,
+                ZSTD_compressBlock_lazy_extDict_row,
+                ZSTD_compressBlock_lazy2_extDict_row,
+            },
+            new ZSTD_blockCompressor[3]
+            {
+                ZSTD_compressBlock_greedy_dictMatchState_row,
+                ZSTD_compressBlock_lazy_dictMatchState_row,
+                ZSTD_compressBlock_lazy2_dictMatchState_row,
+            },
+            new ZSTD_blockCompressor[3]
+            {
+                ZSTD_compressBlock_greedy_dedicatedDictSearch_row,
+                ZSTD_compressBlock_lazy_dedicatedDictSearch_row,
+                ZSTD_compressBlock_lazy2_dedicatedDictSearch_row,
+            },
+        };
+        static searchMax_f?[][] searchFuncs = new searchMax_f?[4][] 
+                                              {
+                                                  new searchMax_f[3]
+                                                  {
+                                                      ZSTD_HcFindBestMatch_selectMLS,
+                                                      ZSTD_BtFindBestMatch_selectMLS,
+                                                      ZSTD_RowFindBestMatch_selectRowLog,
+                                                  },
+                                                  new searchMax_f?[3]
+                                                  {
+                                                      null,
+                                                      null,
+                                                      null,
+                                                  },
+                                                  new searchMax_f[3]
+                                                  {
+                                                      ZSTD_HcFindBestMatch_dictMatchState_selectMLS,
+                                                      ZSTD_BtFindBestMatch_dictMatchState_selectMLS,
+                                                      ZSTD_RowFindBestMatch_dictMatchState_selectRowLog,
+                                                  },
+                                                  new searchMax_f?[3]
+                                                  {
+                                                      ZSTD_HcFindBestMatch_dedicatedDictSearch_selectMLS,
+                                                      null,
+                                                      ZSTD_RowFindBestMatch_dedicatedDictSearch_selectRowLog,
+                                                  },
+                                              };
+        static searchMax_f[] searchFuncsExtGeneric = new searchMax_f[3] 
+        {
+            ZSTD_HcFindBestMatch_extDict_selectMLS,
+            ZSTD_BtFindBestMatch_extDict_selectMLS,
+            ZSTD_RowFindBestMatch_extDict_selectRowLog,
+        };
+        static decompressionAlgo[] decompress = new decompressionAlgo[2] 
+        {
+            HUF_decompress4X1,
+            HUF_decompress4X2,
+        };
+        static uint* dec32table = GetArrayPointer(new uint[8] 
+        {
+            0,
+            1,
+            2,
+            1,
+            4,
+            4,
+            4,
+            4,
+        });
+        static int* dec64table = GetArrayPointer(new int[8] 
+        {
+            8,
+            8,
+            8,
+            7,
+            8,
+            9,
+            10,
+            11,
+        });
+
+        private static byte* emptyString = GetArrayPointer(new byte[] {0});
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/BIT_CStream_t.cs

@@ -0,0 +1,24 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /*-******************************************
+    *  bitStream encoding API (write forward)
+    ********************************************/
+    /* bitStream can mix input from multiple sources.
+     * A critical property of these streams is that they encode and decode in **reverse** direction.
+     * So the first bit sequence you add will be the last to be read, like a LIFO stack.
+     */
+    public unsafe partial struct BIT_CStream_t
+    {
+        public nuint bitContainer;
+
+        public uint bitPos;
+
+        public sbyte* startPtr;
+
+        public sbyte* ptr;
+
+        public sbyte* endPtr;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/BIT_DStream_status.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    public enum BIT_DStream_status
+    {
+        BIT_DStream_unfinished = 0,
+        BIT_DStream_endOfBuffer = 1,
+        BIT_DStream_completed = 2,
+        BIT_DStream_overflow = 3,
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/BIT_DStream_t.cs

@@ -0,0 +1,20 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /*-********************************************
+    *  bitStream decoding API (read backward)
+    **********************************************/
+    public unsafe partial struct BIT_DStream_t
+    {
+        public nuint bitContainer;
+
+        public uint bitsConsumed;
+
+        public sbyte* ptr;
+
+        public sbyte* start;
+
+        public sbyte* limitPtr;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/Bitstream.cs

@@ -0,0 +1,420 @@
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using static ZstdSharp.UnsafeHelper;
+
+namespace ZstdSharp.Unsafe
+{
+    public static unsafe partial class Methods
+    {
+        /*-**************************************************************
+        *  Internal functions
+        ****************************************************************/
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        [InlineMethod.Inline]
+        private static uint BIT_highbit32(uint val)
+        {
+            assert(val != 0);
+
+            {
+                return (uint) BitOperations.Log2(val);
+            }
+        }
+
+        public static uint* BIT_mask = GetArrayPointer(new uint[32]
+        {
+            0,
+            1,
+            3,
+            7,
+            0xF,
+            0x1F,
+            0x3F,
+            0x7F,
+            0xFF,
+            0x1FF,
+            0x3FF,
+            0x7FF,
+            0xFFF,
+            0x1FFF,
+            0x3FFF,
+            0x7FFF,
+            0xFFFF,
+            0x1FFFF,
+            0x3FFFF,
+            0x7FFFF,
+            0xFFFFF,
+            0x1FFFFF,
+            0x3FFFFF,
+            0x7FFFFF,
+            0xFFFFFF,
+            0x1FFFFFF,
+            0x3FFFFFF,
+            0x7FFFFFF,
+            0xFFFFFFF,
+            0x1FFFFFFF,
+            0x3FFFFFFF,
+            0x7FFFFFFF,
+        });
+
+        /*-**************************************************************
+        *  bitStream encoding
+        ****************************************************************/
+        /*! BIT_initCStream() :
+         *  `dstCapacity` must be > sizeof(size_t)
+         *  @return : 0 if success,
+         *            otherwise an error code (can be tested using ERR_isError()) */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_initCStream(BIT_CStream_t* bitC, void* startPtr, nuint dstCapacity)
+        {
+            bitC->bitContainer = 0;
+            bitC->bitPos = 0;
+            bitC->startPtr = (sbyte*)(startPtr);
+            bitC->ptr = bitC->startPtr;
+            bitC->endPtr = bitC->startPtr + dstCapacity - (nuint)(sizeof(nuint));
+            if (dstCapacity <= (nuint)(sizeof(nuint)))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall)));
+            }
+
+            return 0;
+        }
+
+        /*! BIT_addBits() :
+         *  can add up to 31 bits into `bitC`.
+         *  Note : does not check for register overflow ! */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void BIT_addBits(BIT_CStream_t* bitC, nuint value, uint nbBits)
+        {
+            assert(nbBits < ((nuint)(sizeof(uint) * 32) / (nuint)(sizeof(uint))));
+            assert(nbBits + bitC->bitPos < (nuint)(sizeof(nuint)) * 8);
+            bitC->bitContainer |= (value & BIT_mask[nbBits]) << (int)bitC->bitPos;
+            bitC->bitPos += nbBits;
+        }
+
+        /*! BIT_addBitsFast() :
+         *  works only if `value` is _clean_,
+         *  meaning all high bits above nbBits are 0 */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void BIT_addBitsFast(BIT_CStream_t* bitC, nuint value, uint nbBits)
+        {
+            assert((value >> (int)nbBits) == 0);
+            assert(nbBits + bitC->bitPos < (nuint)(sizeof(nuint)) * 8);
+            bitC->bitContainer |= value << (int)bitC->bitPos;
+            bitC->bitPos += nbBits;
+        }
+
+        /*! BIT_flushBitsFast() :
+         *  assumption : bitContainer has not overflowed
+         *  unsafe version; does not check buffer overflow */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void BIT_flushBitsFast(BIT_CStream_t* bitC)
+        {
+            nuint nbBytes = bitC->bitPos >> 3;
+
+            assert(bitC->bitPos < (nuint)(sizeof(nuint)) * 8);
+            assert(bitC->ptr <= bitC->endPtr);
+            MEM_writeLEST((void*)bitC->ptr, bitC->bitContainer);
+            bitC->ptr += nbBytes;
+            bitC->bitPos &= 7;
+            bitC->bitContainer >>= (int)(nbBytes * 8);
+        }
+
+        /*! BIT_flushBits() :
+         *  assumption : bitContainer has not overflowed
+         *  safe version; check for buffer overflow, and prevents it.
+         *  note : does not signal buffer overflow.
+         *  overflow will be revealed later on using BIT_closeCStream() */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void BIT_flushBits(BIT_CStream_t* bitC)
+        {
+            nuint nbBytes = bitC->bitPos >> 3;
+
+            assert(bitC->bitPos < (nuint)(sizeof(nuint)) * 8);
+            assert(bitC->ptr <= bitC->endPtr);
+            MEM_writeLEST((void*)bitC->ptr, bitC->bitContainer);
+            bitC->ptr += nbBytes;
+            if (bitC->ptr > bitC->endPtr)
+            {
+                bitC->ptr = bitC->endPtr;
+            }
+
+            bitC->bitPos &= 7;
+            bitC->bitContainer >>= (int)(nbBytes * 8);
+        }
+
+        /*! BIT_closeCStream() :
+         *  @return : size of CStream, in bytes,
+         *            or 0 if it could not fit into dstBuffer */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_closeCStream(BIT_CStream_t* bitC)
+        {
+            BIT_addBitsFast(bitC, 1, 1);
+            BIT_flushBits(bitC);
+            if (bitC->ptr >= bitC->endPtr)
+            {
+                return 0;
+            }
+
+            return (nuint)((bitC->ptr - bitC->startPtr) + (((bitC->bitPos > 0)) ? 1 : 0));
+        }
+
+        /*-********************************************************
+        *  bitStream decoding
+        **********************************************************/
+        /*! BIT_initDStream() :
+         *  Initialize a BIT_DStream_t.
+         * `bitD` : a pointer to an already allocated BIT_DStream_t structure.
+         * `srcSize` must be the *exact* size of the bitStream, in bytes.
+         * @return : size of stream (== srcSize), or an errorCode if a problem is detected
+         */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_initDStream(BIT_DStream_t* bitD, void* srcBuffer, nuint srcSize)
+        {
+            if (srcSize < 1)
+            {
+                memset((void*)(bitD), (0), ((nuint)(sizeof(BIT_DStream_t))));
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong)));
+            }
+
+            bitD->start = (sbyte*)(srcBuffer);
+            bitD->limitPtr = bitD->start + (nuint)(sizeof(nuint));
+            if (srcSize >= (nuint)(sizeof(nuint)))
+            {
+                bitD->ptr = (sbyte*)(srcBuffer) + srcSize - (nuint)(sizeof(nuint));
+                bitD->bitContainer = MEM_readLEST((void*)bitD->ptr);
+
+                {
+                    byte lastByte = ((byte*)(srcBuffer))[srcSize - 1];
+
+                    bitD->bitsConsumed = lastByte != 0 ? 8 - BIT_highbit32(lastByte) : 0;
+                    if (lastByte == 0)
+                    {
+                        return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+                    }
+                }
+            }
+            else
+            {
+                bitD->ptr = bitD->start;
+                bitD->bitContainer = *(byte*)(bitD->start);
+                switch (srcSize)
+                {
+                    case 7:
+                    {
+                        bitD->bitContainer += (nuint)(((byte*)(srcBuffer))[6]) << (int)((nuint)(sizeof(nuint)) * 8 - 16);
+                    }
+
+
+                    goto case 6;
+                    case 6:
+                    {
+                        bitD->bitContainer += (nuint)(((byte*)(srcBuffer))[5]) << (int)((nuint)(sizeof(nuint)) * 8 - 24);
+                    }
+
+
+                    goto case 5;
+                    case 5:
+                    {
+                        bitD->bitContainer += (nuint)(((byte*)(srcBuffer))[4]) << (int)((nuint)(sizeof(nuint)) * 8 - 32);
+                    }
+
+
+                    goto case 4;
+                    case 4:
+                    {
+                        bitD->bitContainer += (nuint)(((byte*)(srcBuffer))[3]) << 24;
+                    }
+
+
+                    goto case 3;
+                    case 3:
+                    {
+                        bitD->bitContainer += (nuint)(((byte*)(srcBuffer))[2]) << 16;
+                    }
+
+
+                    goto case 2;
+                    case 2:
+                    {
+                        bitD->bitContainer += (nuint)(((byte*)(srcBuffer))[1]) << 8;
+                    }
+
+
+                    goto default;
+                    default:
+                    {
+                        break;
+                    }
+                }
+
+
+                {
+                    byte lastByte = ((byte*)(srcBuffer))[srcSize - 1];
+
+                    bitD->bitsConsumed = lastByte != 0 ? 8 - BIT_highbit32(lastByte) : 0;
+                    if (lastByte == 0)
+                    {
+                        return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+                    }
+                }
+
+                bitD->bitsConsumed += (uint)((nuint)(sizeof(nuint)) - srcSize) * 8;
+            }
+
+            return srcSize;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_getUpperBits(nuint bitContainer, uint start)
+        {
+            return bitContainer >> (int)start;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_getMiddleBits(nuint bitContainer, uint start, uint nbBits)
+        {
+            uint regMask = (uint)((nuint)(sizeof(nuint)) * 8 - 1);
+
+            assert(nbBits < ((nuint)(sizeof(uint) * 32) / (nuint)(sizeof(uint))));
+            return (bitContainer >> (int)(start & regMask)) & BIT_mask[nbBits];
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_getLowerBits(nuint bitContainer, uint nbBits)
+        {
+            assert(nbBits < ((nuint)(sizeof(uint) * 32) / (nuint)(sizeof(uint))));
+            return bitContainer & BIT_mask[nbBits];
+        }
+
+        /*! BIT_lookBits() :
+         *  Provides next n bits from local register.
+         *  local register is not modified.
+         *  On 32-bits, maxNbBits==24.
+         *  On 64-bits, maxNbBits==56.
+         * @return : value extracted */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_lookBits(BIT_DStream_t* bitD, uint nbBits)
+        {
+            return BIT_getMiddleBits(bitD->bitContainer, (uint)(((nuint)(sizeof(nuint)) * 8) - bitD->bitsConsumed - nbBits), nbBits);
+        }
+
+        /*! BIT_lookBitsFast() :
+         *  unsafe version; only works if nbBits >= 1 */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_lookBitsFast(BIT_DStream_t* bitD, uint nbBits)
+        {
+            uint regMask = (uint)((nuint)(sizeof(nuint)) * 8 - 1);
+
+            assert(nbBits >= 1);
+            return (bitD->bitContainer << (int)(bitD->bitsConsumed & regMask)) >> (int)(((regMask + 1) - nbBits) & regMask);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void BIT_skipBits(BIT_DStream_t* bitD, uint nbBits)
+        {
+            bitD->bitsConsumed += nbBits;
+        }
+
+        /*! BIT_readBits() :
+         *  Read (consume) next n bits from local register and update.
+         *  Pay attention to not read more than nbBits contained into local register.
+         * @return : extracted value. */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_readBits(BIT_DStream_t* bitD, uint nbBits)
+        {
+            nuint value = BIT_lookBits(bitD, nbBits);
+
+            BIT_skipBits(bitD, nbBits);
+            return value;
+        }
+
+        /*! BIT_readBitsFast() :
+         *  unsafe version; only works only if nbBits >= 1 */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint BIT_readBitsFast(BIT_DStream_t* bitD, uint nbBits)
+        {
+            nuint value = BIT_lookBitsFast(bitD, nbBits);
+
+            assert(nbBits >= 1);
+            BIT_skipBits(bitD, nbBits);
+            return value;
+        }
+
+        /*! BIT_reloadDStreamFast() :
+         *  Similar to BIT_reloadDStream(), but with two differences:
+         *  1. bitsConsumed <= sizeof(bitD->bitContainer)*8 must hold!
+         *  2. Returns BIT_DStream_overflow when bitD->ptr < bitD->limitPtr, at this
+         *     point you must use BIT_reloadDStream() to reload.
+         */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static BIT_DStream_status BIT_reloadDStreamFast(BIT_DStream_t* bitD)
+        {
+            if ((bitD->ptr < bitD->limitPtr))
+            {
+                return BIT_DStream_status.BIT_DStream_overflow;
+            }
+
+            assert(bitD->bitsConsumed <= (nuint)(sizeof(nuint)) * 8);
+            bitD->ptr -= bitD->bitsConsumed >> 3;
+            bitD->bitsConsumed &= 7;
+            bitD->bitContainer = MEM_readLEST((void*)bitD->ptr);
+            return BIT_DStream_status.BIT_DStream_unfinished;
+        }
+
+        /*! BIT_reloadDStream() :
+         *  Refill `bitD` from buffer previously set in BIT_initDStream() .
+         *  This function is safe, it guarantees it will not read beyond src buffer.
+         * @return : status of `BIT_DStream_t` internal register.
+         *           when status == BIT_DStream_unfinished, internal register is filled with at least 25 or 57 bits */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)
+        {
+            if (bitD->bitsConsumed > ((nuint)(sizeof(nuint)) * 8))
+            {
+                return BIT_DStream_status.BIT_DStream_overflow;
+            }
+
+            if (bitD->ptr >= bitD->limitPtr)
+            {
+                return BIT_reloadDStreamFast(bitD);
+            }
+
+            if (bitD->ptr == bitD->start)
+            {
+                if (bitD->bitsConsumed < (nuint)(sizeof(nuint)) * 8)
+                {
+                    return BIT_DStream_status.BIT_DStream_endOfBuffer;
+                }
+
+                return BIT_DStream_status.BIT_DStream_completed;
+            }
+
+
+            {
+                uint nbBytes = bitD->bitsConsumed >> 3;
+                BIT_DStream_status result = BIT_DStream_status.BIT_DStream_unfinished;
+
+                if (bitD->ptr - nbBytes < bitD->start)
+                {
+                    nbBytes = (uint)(bitD->ptr - bitD->start);
+                    result = BIT_DStream_status.BIT_DStream_endOfBuffer;
+                }
+
+                bitD->ptr -= nbBytes;
+                bitD->bitsConsumed -= nbBytes * 8;
+                bitD->bitContainer = MEM_readLEST((void*)bitD->ptr);
+                return result;
+            }
+        }
+
+        /*! BIT_endOfDStream() :
+         * @return : 1 if DStream has _exactly_ reached its end (all bits consumed).
+         */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint BIT_endOfDStream(BIT_DStream_t* DStream)
+        {
+            return ((((DStream->ptr == DStream->start) && (DStream->bitsConsumed == (nuint)(sizeof(nuint)) * 8))) ? 1U : 0U);
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/COVER_best_s.cs

@@ -0,0 +1,29 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /**
+     * COVER_best_t is used for two purposes:
+     * 1. Synchronizing threads.
+     * 2. Saving the best parameters and dictionary.
+     *
+     * All of the methods except COVER_best_init() are thread safe if zstd is
+     * compiled with multithreaded support.
+     */
+    public unsafe partial struct COVER_best_s
+    {
+        public int mutex;
+
+        public int cond;
+
+        public nuint liveJobs;
+
+        public void* dict;
+
+        public nuint dictSize;
+
+        public ZDICT_cover_params_t parameters;
+
+        public nuint compressedSize;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/COVER_dictSelection.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /**
+     * Struct used for the dictionary selection function.
+     */
+    public unsafe partial struct COVER_dictSelection
+    {
+        public byte* dictContent;
+
+        public nuint dictSize;
+
+        public nuint totalCompressedSize;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/COVER_epoch_info_t.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /**
+     *Number of epochs and size of each epoch.
+     */
+    public partial struct COVER_epoch_info_t
+    {
+        public uint num;
+
+        public uint size;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/COVER_segment_t.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /**
+     * A segment is a range in the source as well as the score of the segment.
+     */
+    public partial struct COVER_segment_t
+    {
+        public uint begin;
+
+        public uint end;
+
+        public uint score;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/Cover.cs

@@ -0,0 +1,411 @@
+using System;
+using static ZstdSharp.UnsafeHelper;
+
+namespace ZstdSharp.Unsafe
+{
+    public static unsafe partial class Methods
+    {
+        public static int g_displayLevel = 2;
+
+        /**
+         * Returns the sum of the sample sizes.
+         */
+        public static nuint COVER_sum(nuint* samplesSizes, uint nbSamples)
+        {
+            nuint sum = 0;
+            uint i;
+
+            for (i = 0; i < nbSamples; ++i)
+            {
+                sum += samplesSizes[i];
+            }
+
+            return sum;
+        }
+
+        /**
+         * Warns the user when their corpus is too small.
+         */
+        public static void COVER_warnOnSmallCorpus(nuint maxDictSize, nuint nbDmers, int displayLevel)
+        {
+            double ratio = (double)(nbDmers) / maxDictSize;
+
+            if (ratio >= 10)
+            {
+                return;
+            }
+
+            if (displayLevel >= 1)
+            {
+        ;
+            }
+
+        }
+
+        /**
+         * Computes the number of epochs and the size of each epoch.
+         * We will make sure that each epoch gets at least 10 * k bytes.
+         *
+         * The COVER algorithms divide the data up into epochs of equal size and
+         * select one segment from each epoch.
+         *
+         * @param maxDictSize The maximum allowed dictionary size.
+         * @param nbDmers     The number of dmers we are training on.
+         * @param k           The parameter k (segment size).
+         * @param passes      The target number of passes over the dmer corpus.
+         *                    More passes means a better dictionary.
+         */
+        public static COVER_epoch_info_t COVER_computeEpochs(uint maxDictSize, uint nbDmers, uint k, uint passes)
+        {
+            uint minEpochSize = k * 10;
+            COVER_epoch_info_t epochs;
+
+            epochs.num = (uint)((1) > (maxDictSize / k / passes) ? (1) : (maxDictSize / k / passes));
+            epochs.size = nbDmers / epochs.num;
+            if (epochs.size >= minEpochSize)
+            {
+                assert(epochs.size * epochs.num <= nbDmers);
+                return epochs;
+            }
+
+            epochs.size = ((minEpochSize) < (nbDmers) ? (minEpochSize) : (nbDmers));
+            epochs.num = nbDmers / epochs.size;
+            assert(epochs.size * epochs.num <= nbDmers);
+            return epochs;
+        }
+
+        /**
+         *  Checks total compressed size of a dictionary
+         */
+        public static nuint COVER_checkTotalCompressedSize(ZDICT_cover_params_t parameters, nuint* samplesSizes, byte* samples, nuint* offsets, nuint nbTrainSamples, nuint nbSamples, byte* dict, nuint dictBufferCapacity)
+        {
+            nuint totalCompressedSize = (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            ZSTD_CCtx_s* cctx;
+            ZSTD_CDict_s* cdict;
+            void* dst;
+            nuint dstCapacity;
+            nuint i;
+
+
+            {
+                nuint maxSampleSize = 0;
+
+                i = parameters.splitPoint < 1.0 ? nbTrainSamples : 0;
+                for (; i < nbSamples; ++i)
+                {
+                    maxSampleSize = ((samplesSizes[i]) > (maxSampleSize) ? (samplesSizes[i]) : (maxSampleSize));
+                }
+
+                dstCapacity = ZSTD_compressBound(maxSampleSize);
+                dst = malloc(dstCapacity);
+            }
+
+            cctx = ZSTD_createCCtx();
+            cdict = ZSTD_createCDict((void*)dict, dictBufferCapacity, parameters.zParams.compressionLevel);
+            if (dst == null || cctx == null || cdict == null)
+            {
+                goto _compressCleanup;
+            }
+
+            totalCompressedSize = dictBufferCapacity;
+            i = parameters.splitPoint < 1.0 ? nbTrainSamples : 0;
+            for (; i < nbSamples; ++i)
+            {
+                nuint size = ZSTD_compress_usingCDict(cctx, dst, dstCapacity, (void*)(samples + offsets[i]), samplesSizes[i], cdict);
+
+                if ((ERR_isError(size)) != 0)
+                {
+                    totalCompressedSize = size;
+                    goto _compressCleanup;
+                }
+
+                totalCompressedSize += size;
+            }
+
+            _compressCleanup:
+            ZSTD_freeCCtx(cctx);
+            ZSTD_freeCDict(cdict);
+            if (dst != null)
+            {
+                free(dst);
+            }
+
+            return totalCompressedSize;
+        }
+
+        /**
+         * Initialize the `COVER_best_t`.
+         */
+        public static void COVER_best_init(COVER_best_s* best)
+        {
+            if (best == null)
+            {
+                return;
+            }
+
+
+
+            best->liveJobs = 0;
+            best->dict = null;
+            best->dictSize = 0;
+            best->compressedSize = unchecked((nuint)(-1));
+            memset((void*)&best->parameters, 0, (nuint)(sizeof(ZDICT_cover_params_t)));
+        }
+
+        /**
+         * Wait until liveJobs == 0.
+         */
+        public static void COVER_best_wait(COVER_best_s* best)
+        {
+            if (best == null)
+            {
+                return;
+            }
+
+
+            while (best->liveJobs != 0)
+            {
+
+            }
+
+
+        }
+
+        /**
+         * Call COVER_best_wait() and then destroy the COVER_best_t.
+         */
+        public static void COVER_best_destroy(COVER_best_s* best)
+        {
+            if (best == null)
+            {
+                return;
+            }
+
+            COVER_best_wait(best);
+            if (best->dict != null)
+            {
+                free(best->dict);
+            }
+
+
+
+        }
+
+        /**
+         * Called when a thread is about to be launched.
+         * Increments liveJobs.
+         */
+        public static void COVER_best_start(COVER_best_s* best)
+        {
+            if (best == null)
+            {
+                return;
+            }
+
+
+            ++best->liveJobs;
+
+        }
+
+        /**
+         * Called when a thread finishes executing, both on error or success.
+         * Decrements liveJobs and signals any waiting threads if liveJobs == 0.
+         * If this dictionary is the best so far save it and its parameters.
+         */
+        public static void COVER_best_finish(COVER_best_s* best, ZDICT_cover_params_t parameters, COVER_dictSelection selection)
+        {
+            void* dict = (void*)selection.dictContent;
+            nuint compressedSize = selection.totalCompressedSize;
+            nuint dictSize = selection.dictSize;
+
+            if (best == null)
+            {
+                return;
+            }
+
+
+            {
+                nuint liveJobs;
+
+
+                --best->liveJobs;
+                liveJobs = best->liveJobs;
+                if (compressedSize < best->compressedSize)
+                {
+                    if (best->dict == null || best->dictSize < dictSize)
+                    {
+                        if (best->dict != null)
+                        {
+                            free(best->dict);
+                        }
+
+                        best->dict = malloc(dictSize);
+                        if (best->dict == null)
+                        {
+                            best->compressedSize = (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+                            best->dictSize = 0;
+
+
+                            return;
+                        }
+                    }
+
+                    if (dict != null)
+                    {
+                        memcpy(best->dict, dict, dictSize);
+                        best->dictSize = dictSize;
+                        best->parameters = parameters;
+                        best->compressedSize = compressedSize;
+                    }
+                }
+
+                if (liveJobs == 0)
+                {
+
+                }
+
+
+            }
+        }
+
+        /**
+          * Error function for COVER_selectDict function. Returns a struct where
+          * return.totalCompressedSize is a ZSTD error.
+          */
+        public static COVER_dictSelection COVER_dictSelectionError(nuint error)
+        {
+            COVER_dictSelection selection = new COVER_dictSelection
+            {
+                dictContent = null,
+                dictSize = 0,
+                totalCompressedSize = error,
+            };
+
+            return selection;
+        }
+
+        /**
+         * Error function for COVER_selectDict function. Checks if the return
+         * value is an error.
+         */
+        public static uint COVER_dictSelectionIsError(COVER_dictSelection selection)
+        {
+            return ((((ERR_isError(selection.totalCompressedSize)) != 0 || selection.dictContent == null)) ? 1U : 0U);
+        }
+
+        /**
+         * Always call after selectDict is called to free up used memory from
+         * newly created dictionary.
+         */
+        public static void COVER_dictSelectionFree(COVER_dictSelection selection)
+        {
+            free((void*)selection.dictContent);
+        }
+
+        /**
+         * Called to finalize the dictionary and select one based on whether or not
+         * the shrink-dict flag was enabled. If enabled the dictionary used is the
+         * smallest dictionary within a specified regression of the compressed size
+         * from the largest dictionary.
+         */
+        public static COVER_dictSelection COVER_selectDict(byte* customDictContent, nuint dictBufferCapacity, nuint dictContentSize, byte* samplesBuffer, nuint* samplesSizes, uint nbFinalizeSamples, nuint nbCheckSamples, nuint nbSamples, ZDICT_cover_params_t @params, nuint* offsets, nuint totalCompressedSize)
+        {
+            nuint largestDict = 0;
+            nuint largestCompressed = 0;
+            byte* customDictContentEnd = customDictContent + dictContentSize;
+            byte* largestDictbuffer = (byte*)(malloc(dictBufferCapacity));
+            byte* candidateDictBuffer = (byte*)(malloc(dictBufferCapacity));
+            double regressionTolerance = ((double)(@params.shrinkDictMaxRegression) / 100.0) + 1.00;
+
+            if (largestDictbuffer == null || candidateDictBuffer == null)
+            {
+                free((void*)largestDictbuffer);
+                free((void*)candidateDictBuffer);
+                return COVER_dictSelectionError(dictContentSize);
+            }
+
+            memcpy((void*)largestDictbuffer, (void*)customDictContent, dictContentSize);
+            dictContentSize = ZDICT_finalizeDictionary((void*)largestDictbuffer, dictBufferCapacity, (void*)customDictContent, dictContentSize, (void*)samplesBuffer, samplesSizes, nbFinalizeSamples, @params.zParams);
+            if ((ZDICT_isError(dictContentSize)) != 0)
+            {
+                free((void*)largestDictbuffer);
+                free((void*)candidateDictBuffer);
+                return COVER_dictSelectionError(dictContentSize);
+            }
+
+            totalCompressedSize = COVER_checkTotalCompressedSize(@params, samplesSizes, samplesBuffer, offsets, nbCheckSamples, nbSamples, largestDictbuffer, dictContentSize);
+            if ((ERR_isError(totalCompressedSize)) != 0)
+            {
+                free((void*)largestDictbuffer);
+                free((void*)candidateDictBuffer);
+                return COVER_dictSelectionError(totalCompressedSize);
+            }
+
+            if (@params.shrinkDict == 0)
+            {
+                COVER_dictSelection selection = new COVER_dictSelection
+                {
+                    dictContent = largestDictbuffer,
+                    dictSize = dictContentSize,
+                    totalCompressedSize = totalCompressedSize,
+                };
+
+                free((void*)candidateDictBuffer);
+                return selection;
+            }
+
+            largestDict = dictContentSize;
+            largestCompressed = totalCompressedSize;
+            dictContentSize = 256;
+            while (dictContentSize < largestDict)
+            {
+                memcpy((void*)candidateDictBuffer, (void*)largestDictbuffer, largestDict);
+                dictContentSize = ZDICT_finalizeDictionary((void*)candidateDictBuffer, dictBufferCapacity, (void*)(customDictContentEnd - dictContentSize), dictContentSize, (void*)samplesBuffer, samplesSizes, nbFinalizeSamples, @params.zParams);
+                if ((ZDICT_isError(dictContentSize)) != 0)
+                {
+                    free((void*)largestDictbuffer);
+                    free((void*)candidateDictBuffer);
+                    return COVER_dictSelectionError(dictContentSize);
+                }
+
+                totalCompressedSize = COVER_checkTotalCompressedSize(@params, samplesSizes, samplesBuffer, offsets, nbCheckSamples, nbSamples, candidateDictBuffer, dictContentSize);
+                if ((ERR_isError(totalCompressedSize)) != 0)
+                {
+                    free((void*)largestDictbuffer);
+                    free((void*)candidateDictBuffer);
+                    return COVER_dictSelectionError(totalCompressedSize);
+                }
+
+                if (totalCompressedSize <= largestCompressed * regressionTolerance)
+                {
+                    COVER_dictSelection selection = new COVER_dictSelection
+                    {
+                        dictContent = candidateDictBuffer,
+                        dictSize = dictContentSize,
+                        totalCompressedSize = totalCompressedSize,
+                    };
+
+                    free((void*)largestDictbuffer);
+                    return selection;
+                }
+
+                dictContentSize *= 2;
+            }
+
+            dictContentSize = largestDict;
+            totalCompressedSize = largestCompressed;
+
+            {
+                COVER_dictSelection selection = new COVER_dictSelection
+                {
+                    dictContent = largestDictbuffer,
+                    dictSize = dictContentSize,
+                    totalCompressedSize = totalCompressedSize,
+                };
+
+                free((void*)candidateDictBuffer);
+                return selection;
+            }
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/DTableDesc.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /*-***************************/
+    /*  generic DTableDesc       */
+    /*-***************************/
+    public partial struct DTableDesc
+    {
+        public byte maxTableLog;
+
+        public byte tableType;
+
+        public byte tableLog;
+
+        public byte reserved;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/EStats_ress_t.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    public unsafe partial struct EStats_ress_t
+    {
+        /* dictionary */
+        public ZSTD_CDict_s* dict;
+
+        /* working context */
+        public ZSTD_CCtx_s* zc;
+
+        /* must be ZSTD_BLOCKSIZE_MAX allocated */
+        public void* workPlace;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/EntropyCommon.cs

@@ -0,0 +1,425 @@
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using static ZstdSharp.UnsafeHelper;
+
+namespace ZstdSharp.Unsafe
+{
+    public static unsafe partial class Methods
+    {
+        /*===   Version   ===*/
+        public static uint FSE_versionNumber()
+        {
+            return (uint)((0 * 100 * 100 + 9 * 100 + 0));
+        }
+
+        /*===   Error Management   ===*/
+        public static uint FSE_isError(nuint code)
+        {
+            return ERR_isError(code);
+        }
+
+        public static string FSE_getErrorName(nuint code)
+        {
+            return ERR_getErrorName(code);
+        }
+
+        /* Error Management */
+        public static uint HUF_isError(nuint code)
+        {
+            return ERR_isError(code);
+        }
+
+        public static string HUF_getErrorName(nuint code)
+        {
+            return ERR_getErrorName(code);
+        }
+
+        /*-**************************************************************
+        *  FSE NCount encoding-decoding
+        ****************************************************************/
+        [InlineMethod.Inline]
+        private static uint FSE_ctz(uint val)
+        {
+            assert(val != 0);
+
+            {
+                return (uint) BitOperations.TrailingZeroCount(val);
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint FSE_readNCount_body(short* normalizedCounter, uint* maxSVPtr, uint* tableLogPtr, void* headerBuffer, nuint hbSize)
+        {
+            byte* istart = (byte*)(headerBuffer);
+            byte* iend = istart + hbSize;
+            byte* ip = istart;
+            int nbBits;
+            int remaining;
+            int threshold;
+            uint bitStream;
+            int bitCount;
+            uint charnum = 0;
+            uint maxSV1 = *maxSVPtr + 1;
+            int previous0 = 0;
+
+            if (hbSize < 8)
+            {
+                sbyte* buffer = stackalloc sbyte[8];
+                memset(buffer, 0, sizeof(sbyte) * 8);
+
+                memcpy((void*)(buffer), (headerBuffer), (hbSize));
+
+                {
+                    nuint countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr, (void*)buffer, (nuint)(8));
+
+                    if ((FSE_isError(countSize)) != 0)
+                    {
+                        return countSize;
+                    }
+
+                    if (countSize > hbSize)
+                    {
+                        return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+                    }
+
+                    return countSize;
+                }
+            }
+
+            assert(hbSize >= 8);
+            memset((void*)(normalizedCounter), (0), ((*maxSVPtr + 1) * (nuint)(sizeof(short))));
+            bitStream = MEM_readLE32((void*)ip);
+            nbBits = (int)((bitStream & 0xF) + 5);
+            if (nbBits > 15)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge)));
+            }
+
+            bitStream >>= 4;
+            bitCount = 4;
+            *tableLogPtr = (uint)nbBits;
+            remaining = (1 << nbBits) + 1;
+            threshold = 1 << nbBits;
+            nbBits++;
+            for (;;)
+            {
+                if (previous0 != 0)
+                {
+                    int repeats = (int)(FSE_ctz(~bitStream | 0x80000000) >> 1);
+
+                    while (repeats >= 12)
+                    {
+                        charnum += (uint)(3 * 12);
+                        if ((ip <= iend - 7))
+                        {
+                            ip += 3;
+                        }
+                        else
+                        {
+                            bitCount -= (int)(8 * (iend - 7 - ip));
+                            bitCount &= 31;
+                            ip = iend - 4;
+                        }
+
+                        bitStream = MEM_readLE32((void*)ip) >> bitCount;
+                        repeats = (int)(FSE_ctz(~bitStream | 0x80000000) >> 1);
+                    }
+
+                    charnum += (uint)(3 * repeats);
+                    bitStream >>= 2 * repeats;
+                    bitCount += 2 * repeats;
+                    assert((bitStream & 3) < 3);
+                    charnum += bitStream & 3;
+                    bitCount += 2;
+                    if (charnum >= maxSV1)
+                    {
+                        break;
+                    }
+
+                    if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4))
+                    {
+                        assert((bitCount >> 3) <= 3);
+                        ip += bitCount >> 3;
+                        bitCount &= 7;
+                    }
+                    else
+                    {
+                        bitCount -= (int)(8 * (iend - 4 - ip));
+                        bitCount &= 31;
+                        ip = iend - 4;
+                    }
+
+                    bitStream = MEM_readLE32((void*)ip) >> bitCount;
+                }
+
+
+                {
+                    int max = (2 * threshold - 1) - remaining;
+                    int count;
+
+                    if ((bitStream & (uint)((threshold - 1))) < (uint)(max))
+                    {
+                        count = (int)(bitStream & (uint)((threshold - 1)));
+                        bitCount += nbBits - 1;
+                    }
+                    else
+                    {
+                        count = (int)(bitStream & (uint)((2 * threshold - 1)));
+                        if (count >= threshold)
+                        {
+                            count -= max;
+                        }
+
+                        bitCount += nbBits;
+                    }
+
+                    count--;
+                    if (count >= 0)
+                    {
+                        remaining -= count;
+                    }
+                    else
+                    {
+                        assert(count == -1);
+                        remaining += count;
+                    }
+
+                    normalizedCounter[charnum++] = (short)(count);
+                    previous0 = (count == 0 ? 1 : 0);
+                    assert(threshold > 1);
+                    if (remaining < threshold)
+                    {
+                        if (remaining <= 1)
+                        {
+                            break;
+                        }
+
+                        nbBits = (int)(BIT_highbit32((uint)remaining) + 1);
+                        threshold = 1 << (nbBits - 1);
+                    }
+
+                    if (charnum >= maxSV1)
+                    {
+                        break;
+                    }
+
+                    if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4))
+                    {
+                        ip += bitCount >> 3;
+                        bitCount &= 7;
+                    }
+                    else
+                    {
+                        bitCount -= (int)(8 * (iend - 4 - ip));
+                        bitCount &= 31;
+                        ip = iend - 4;
+                    }
+
+                    bitStream = MEM_readLE32((void*)ip) >> bitCount;
+                }
+            }
+
+            if (remaining != 1)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+            }
+
+            if (charnum > maxSV1)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_maxSymbolValue_tooSmall)));
+            }
+
+            if (bitCount > 32)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+            }
+
+            *maxSVPtr = charnum - 1;
+            ip += (bitCount + 7) >> 3;
+            return (nuint)(ip - istart);
+        }
+
+        /* Avoids the FORCE_INLINE of the _body() function. */
+        private static nuint FSE_readNCount_body_default(short* normalizedCounter, uint* maxSVPtr, uint* tableLogPtr, void* headerBuffer, nuint hbSize)
+        {
+            return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
+        }
+
+        private static nuint FSE_readNCount_body_bmi2(short* normalizedCounter, uint* maxSVPtr, uint* tableLogPtr, void* headerBuffer, nuint hbSize)
+        {
+            return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
+        }
+
+        /*! FSE_readNCount_bmi2():
+         * Same as FSE_readNCount() but pass bmi2=1 when your CPU supports BMI2 and 0 otherwise.
+         */
+        public static nuint FSE_readNCount_bmi2(short* normalizedCounter, uint* maxSVPtr, uint* tableLogPtr, void* headerBuffer, nuint hbSize, int bmi2)
+        {
+            if (bmi2 != 0)
+            {
+                return FSE_readNCount_body_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
+            }
+
+            return FSE_readNCount_body_default(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
+        }
+
+        /*! FSE_readNCount():
+            Read compactly saved 'normalizedCounter' from 'rBuffer'.
+            @return : size read from 'rBuffer',
+                      or an errorCode, which can be tested using FSE_isError().
+                      maxSymbolValuePtr[0] and tableLogPtr[0] will also be updated with their respective values */
+        public static nuint FSE_readNCount(short* normalizedCounter, uint* maxSVPtr, uint* tableLogPtr, void* headerBuffer, nuint hbSize)
+        {
+            return FSE_readNCount_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize, 0);
+        }
+
+        /*! HUF_readStats() :
+            Read compact Huffman tree, saved by HUF_writeCTable().
+            `huffWeight` is destination buffer.
+            `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.
+            @return : size read from `src` , or an error Code .
+            Note : Needed by HUF_readCTable() and HUF_readDTableX?() .
+        */
+        public static nuint HUF_readStats(byte* huffWeight, nuint hwSize, uint* rankStats, uint* nbSymbolsPtr, uint* tableLogPtr, void* src, nuint srcSize)
+        {
+            uint* wksp = stackalloc uint[218];
+
+            return HUF_readStats_wksp(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, (void*)wksp, (nuint)(sizeof(uint) * 218), 0);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint HUF_readStats_body(byte* huffWeight, nuint hwSize, uint* rankStats, uint* nbSymbolsPtr, uint* tableLogPtr, void* src, nuint srcSize, void* workSpace, nuint wkspSize, int bmi2)
+        {
+            uint weightTotal;
+            byte* ip = (byte*)(src);
+            nuint iSize;
+            nuint oSize;
+
+            if (srcSize == 0)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong)));
+            }
+
+            iSize = ip[0];
+            if (iSize >= 128)
+            {
+                oSize = iSize - 127;
+                iSize = ((oSize + 1) / 2);
+                if (iSize + 1 > srcSize)
+                {
+                    return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong)));
+                }
+
+                if (oSize >= hwSize)
+                {
+                    return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+                }
+
+                ip += 1;
+
+                {
+                    uint n;
+
+                    for (n = 0; n < oSize; n += 2)
+                    {
+                        huffWeight[n] = (byte)(ip[n / 2] >> 4);
+                        huffWeight[n + 1] = (byte)(ip[n / 2] & 15);
+                    }
+                }
+            }
+            else
+            {
+                if (iSize + 1 > srcSize)
+                {
+                    return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong)));
+                }
+
+                oSize = FSE_decompress_wksp_bmi2((void*)huffWeight, hwSize - 1, (void*)(ip + 1), iSize, 6, workSpace, wkspSize, bmi2);
+                if ((FSE_isError(oSize)) != 0)
+                {
+                    return oSize;
+                }
+            }
+
+            memset((void*)(rankStats), (0), ((uint)((12 + 1)) * (nuint)(sizeof(uint))));
+            weightTotal = 0;
+
+            {
+                uint n;
+
+                for (n = 0; n < oSize; n++)
+                {
+                    if (huffWeight[n] >= 12)
+                    {
+                        return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+                    }
+
+                    rankStats[huffWeight[n]]++;
+                    weightTotal += (uint)((1 << (int)(huffWeight[n])) >> 1);
+                }
+            }
+
+            if (weightTotal == 0)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+            }
+
+
+            {
+                uint tableLog = BIT_highbit32(weightTotal) + 1;
+
+                if (tableLog > 12)
+                {
+                    return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+                }
+
+                *tableLogPtr = tableLog;
+
+                {
+                    uint total = (uint)(1 << (int)tableLog);
+                    uint rest = total - weightTotal;
+                    uint verif = (uint)(1 << (int)(BIT_highbit32(rest)));
+                    uint lastWeight = BIT_highbit32(rest) + 1;
+
+                    if (verif != rest)
+                    {
+                        return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+                    }
+
+                    huffWeight[oSize] = (byte)(lastWeight);
+                    rankStats[lastWeight]++;
+                }
+            }
+
+            if ((rankStats[1] < 2) || (rankStats[1] & 1) != 0)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected)));
+            }
+
+            *nbSymbolsPtr = (uint)(oSize + 1);
+            return iSize + 1;
+        }
+
+        /* Avoids the FORCE_INLINE of the _body() function. */
+        private static nuint HUF_readStats_body_default(byte* huffWeight, nuint hwSize, uint* rankStats, uint* nbSymbolsPtr, uint* tableLogPtr, void* src, nuint srcSize, void* workSpace, nuint wkspSize)
+        {
+            return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 0);
+        }
+
+        private static nuint HUF_readStats_body_bmi2(byte* huffWeight, nuint hwSize, uint* rankStats, uint* nbSymbolsPtr, uint* tableLogPtr, void* src, nuint srcSize, void* workSpace, nuint wkspSize)
+        {
+            return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 1);
+        }
+
+        public static nuint HUF_readStats_wksp(byte* huffWeight, nuint hwSize, uint* rankStats, uint* nbSymbolsPtr, uint* tableLogPtr, void* src, nuint srcSize, void* workSpace, nuint wkspSize, int bmi2)
+        {
+            if (bmi2 != 0)
+            {
+                return HUF_readStats_body_bmi2(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);
+            }
+
+            return HUF_readStats_body_default(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/ErrorPrivate.cs

@@ -0,0 +1,184 @@
+using System;
+using System.Runtime.CompilerServices;
+using static ZstdSharp.UnsafeHelper;
+
+namespace ZstdSharp.Unsafe
+{
+    public static unsafe partial class Methods
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint ERR_isError(nuint code)
+        {
+            return (((code > (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_maxCode))))) ? 1U : 0U);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static ZSTD_ErrorCode ERR_getErrorCode(nuint code)
+        {
+            if ((ERR_isError(code)) == 0)
+            {
+                return (ZSTD_ErrorCode)(0);
+            }
+
+            return (ZSTD_ErrorCode)(0 - code);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static string ERR_getErrorName(nuint code)
+        {
+            return ERR_getErrorString(ERR_getErrorCode(code));
+        }
+
+        /*-****************************************
+        *  Error Strings
+        ******************************************/
+        public static string ERR_getErrorString(ZSTD_ErrorCode code)
+        {
+            var notErrorCode = "Unspecified error code";
+
+            switch (code)
+            {
+                case ZSTD_ErrorCode.ZSTD_error_no_error:
+                {
+                    return "No error detected";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_GENERIC:
+                {
+                    return "Error (generic)";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_prefix_unknown:
+                {
+                    return "Unknown frame descriptor";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_version_unsupported:
+                {
+                    return "Version not supported";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_frameParameter_unsupported:
+                {
+                    return "Unsupported frame parameter";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_frameParameter_windowTooLarge:
+                {
+                    return "Frame requires too much memory for decoding";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_corruption_detected:
+                {
+                    return "Corrupted block detected";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_checksum_wrong:
+                {
+                    return "Restored data doesn't match checksum";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_parameter_unsupported:
+                {
+                    return "Unsupported parameter";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_parameter_outOfBound:
+                {
+                    return "Parameter is out of bound";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_init_missing:
+                {
+                    return "Context should be init first";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_memory_allocation:
+                {
+                    return "Allocation error : not enough memory";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_workSpace_tooSmall:
+                {
+                    return "workSpace buffer is not large enough";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_stage_wrong:
+                {
+                    return "Operation not authorized at current processing stage";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge:
+                {
+                    return "tableLog requires too much memory : unsupported";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_maxSymbolValue_tooLarge:
+                {
+                    return "Unsupported max Symbol Value : too large";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_maxSymbolValue_tooSmall:
+                {
+                    return "Specified maxSymbolValue is too small";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_dictionary_corrupted:
+                {
+                    return "Dictionary is corrupted";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_dictionary_wrong:
+                {
+                    return "Dictionary mismatch";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_dictionaryCreation_failed:
+                {
+                    return "Cannot create Dictionary from provided samples";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall:
+                {
+                    return "Destination buffer is too small";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_srcSize_wrong:
+                {
+                    return "Src size is incorrect";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_dstBuffer_null:
+                {
+                    return "Operation on NULL destination buffer";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_frameIndex_tooLarge:
+                {
+                    return "Frame index is too large";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_seekableIO:
+                {
+                    return "An I/O error occurred when reading/seeking";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_dstBuffer_wrong:
+                {
+                    return "Destination buffer is wrong";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_srcBuffer_wrong:
+                {
+                    return "Source buffer is wrong";
+                }
+
+                case ZSTD_ErrorCode.ZSTD_error_maxCode:
+                default:
+                {
+                    return notErrorCode;
+                }
+            }
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FASTCOVER_accel_t.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /*-*************************************
+    * Acceleration
+    ***************************************/
+    public partial struct FASTCOVER_accel_t
+    {
+        /* Percentage of training samples used for ZDICT_finalizeDictionary */
+        public uint finalize;
+
+        /* Number of dmer skipped between each dmer counted in computeFrequency */
+        public uint skip;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FASTCOVER_ctx_t.cs

@@ -0,0 +1,32 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /*-*************************************
+    * Context
+    ***************************************/
+    public unsafe partial struct FASTCOVER_ctx_t
+    {
+        public byte* samples;
+
+        public nuint* offsets;
+
+        public nuint* samplesSizes;
+
+        public nuint nbSamples;
+
+        public nuint nbTrainSamples;
+
+        public nuint nbTestSamples;
+
+        public nuint nbDmers;
+
+        public uint* freqs;
+
+        public uint d;
+
+        public uint f;
+
+        public FASTCOVER_accel_t accelParams;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FASTCOVER_tryParameters_data_s.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /**
+     * Parameters for FASTCOVER_tryParameters().
+     */
+    public unsafe partial struct FASTCOVER_tryParameters_data_s
+    {
+        public FASTCOVER_ctx_t* ctx;
+
+        public COVER_best_s* best;
+
+        public nuint dictBufferCapacity;
+
+        public ZDICT_cover_params_t parameters;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FSE_CState_t.cs

@@ -0,0 +1,22 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /* *****************************************
+    *  FSE symbol compression API
+    *******************************************/
+    /*!
+       This API consists of small unitary functions, which highly benefit from being inlined.
+       Hence their body are included in next section.
+    */
+    public unsafe partial struct FSE_CState_t
+    {
+        public nint value;
+
+        public void* stateTable;
+
+        public void* symbolTT;
+
+        public uint stateLog;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FSE_DState_t.cs

@@ -0,0 +1,15 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /* *****************************************
+    *  FSE symbol decompression API
+    *******************************************/
+    public unsafe partial struct FSE_DState_t
+    {
+        public nuint state;
+
+        /* precise table may vary, depending on U16 */
+        public void* table;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FSE_DTableHeader.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /* ======    Decompression    ====== */
+    public partial struct FSE_DTableHeader
+    {
+        public ushort tableLog;
+
+        public ushort fastMode;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FSE_DecompressWksp.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    public unsafe partial struct FSE_DecompressWksp
+    {
+        public fixed short ncount[256];
+
+        /* Dynamically sized */
+        public fixed uint dtable[1];
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FSE_decode_t.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    public partial struct FSE_decode_t
+    {
+        public ushort newState;
+
+        public byte symbol;
+
+        public byte nbBits;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FSE_repeat.cs

@@ -0,0 +1,11 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    public enum FSE_repeat
+    {
+        FSE_repeat_none,
+        FSE_repeat_check,
+        FSE_repeat_valid,
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FSE_symbolCompressionTransform.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /* *****************************************
+    *  Implementation of inlined functions
+    *******************************************/
+    public partial struct FSE_symbolCompressionTransform
+    {
+        public int deltaFindState;
+
+        public uint deltaNbBits;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/Fastcover.cs

@@ -0,0 +1,715 @@
+using System;
+using static ZstdSharp.UnsafeHelper;
+
+namespace ZstdSharp.Unsafe
+{
+    public static unsafe partial class Methods
+    {
+        /*-*************************************
+        * Hash Functions
+        ***************************************/
+        /**
+         * Hash the d-byte value pointed to by p and mod 2^f into the frequency vector
+         */
+        private static nuint FASTCOVER_hashPtrToIndex(void* p, uint f, uint d)
+        {
+            if (d == 6)
+            {
+                return ZSTD_hash6Ptr(p, f);
+            }
+
+            return ZSTD_hash8Ptr(p, f);
+        }
+
+        public static FASTCOVER_accel_t* FASTCOVER_defaultAccelParameters = GetArrayPointer(new FASTCOVER_accel_t[11]
+        {
+            new FASTCOVER_accel_t
+            {
+                finalize = 100,
+                skip = 0,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 100,
+                skip = 0,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 50,
+                skip = 1,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 34,
+                skip = 2,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 25,
+                skip = 3,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 20,
+                skip = 4,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 17,
+                skip = 5,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 14,
+                skip = 6,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 13,
+                skip = 7,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 11,
+                skip = 8,
+            },
+            new FASTCOVER_accel_t
+            {
+                finalize = 10,
+                skip = 9,
+            },
+        });
+
+        /*-*************************************
+        *  Helper functions
+        ***************************************/
+        /**
+         * Selects the best segment in an epoch.
+         * Segments of are scored according to the function:
+         *
+         * Let F(d) be the frequency of all dmers with hash value d.
+         * Let S_i be hash value of the dmer at position i of segment S which has length k.
+         *
+         *     Score(S) = F(S_1) + F(S_2) + ... + F(S_{k-d+1})
+         *
+         * Once the dmer with hash value d is in the dictionary we set F(d) = 0.
+         */
+        private static COVER_segment_t FASTCOVER_selectSegment(FASTCOVER_ctx_t* ctx, uint* freqs, uint begin, uint end, ZDICT_cover_params_t parameters, ushort* segmentFreqs)
+        {
+            uint k = parameters.k;
+            uint d = parameters.d;
+            uint f = ctx->f;
+            uint dmersInK = k - d + 1;
+            COVER_segment_t bestSegment = new COVER_segment_t
+            {
+                begin = 0,
+                end = 0,
+                score = 0,
+            };
+            COVER_segment_t activeSegment;
+
+            activeSegment.begin = begin;
+            activeSegment.end = begin;
+            activeSegment.score = 0;
+            while (activeSegment.end < end)
+            {
+                nuint idx = FASTCOVER_hashPtrToIndex((void*)(ctx->samples + activeSegment.end), f, d);
+
+                if (segmentFreqs[idx] == 0)
+                {
+                    activeSegment.score += freqs[idx];
+                }
+
+                activeSegment.end += 1;
+                segmentFreqs[idx] += 1;
+                if (activeSegment.end - activeSegment.begin == dmersInK + 1)
+                {
+                    nuint delIndex = FASTCOVER_hashPtrToIndex((void*)(ctx->samples + activeSegment.begin), f, d);
+
+                    segmentFreqs[delIndex] -= 1;
+                    if (segmentFreqs[delIndex] == 0)
+                    {
+                        activeSegment.score -= freqs[delIndex];
+                    }
+
+                    activeSegment.begin += 1;
+                }
+
+                if (activeSegment.score > bestSegment.score)
+                {
+                    bestSegment = activeSegment;
+                }
+            }
+
+            while (activeSegment.begin < end)
+            {
+                nuint delIndex = FASTCOVER_hashPtrToIndex((void*)(ctx->samples + activeSegment.begin), f, d);
+
+                segmentFreqs[delIndex] -= 1;
+                activeSegment.begin += 1;
+            }
+
+
+            {
+                uint pos;
+
+                for (pos = bestSegment.begin; pos != bestSegment.end; ++pos)
+                {
+                    nuint i = FASTCOVER_hashPtrToIndex((void*)(ctx->samples + pos), f, d);
+
+                    freqs[i] = 0;
+                }
+            }
+
+            return bestSegment;
+        }
+
+        private static int FASTCOVER_checkParameters(ZDICT_cover_params_t parameters, nuint maxDictSize, uint f, uint accel)
+        {
+            if (parameters.d == 0 || parameters.k == 0)
+            {
+                return 0;
+            }
+
+            if (parameters.d != 6 && parameters.d != 8)
+            {
+                return 0;
+            }
+
+            if (parameters.k > maxDictSize)
+            {
+                return 0;
+            }
+
+            if (parameters.d > parameters.k)
+            {
+                return 0;
+            }
+
+            if (f > 31 || f == 0)
+            {
+                return 0;
+            }
+
+            if (parameters.splitPoint <= 0 || parameters.splitPoint > 1)
+            {
+                return 0;
+            }
+
+            if (accel > 10 || accel == 0)
+            {
+                return 0;
+            }
+
+            return 1;
+        }
+
+        /**
+         * Clean up a context initialized with `FASTCOVER_ctx_init()`.
+         */
+        private static void FASTCOVER_ctx_destroy(FASTCOVER_ctx_t* ctx)
+        {
+            if (ctx == null)
+            {
+                return;
+            }
+
+            free((void*)ctx->freqs);
+            ctx->freqs = null;
+            free((void*)ctx->offsets);
+            ctx->offsets = null;
+        }
+
+        /**
+         * Calculate for frequency of hash value of each dmer in ctx->samples
+         */
+        private static void FASTCOVER_computeFrequency(uint* freqs, FASTCOVER_ctx_t* ctx)
+        {
+            uint f = ctx->f;
+            uint d = ctx->d;
+            uint skip = ctx->accelParams.skip;
+            uint readLength = ((d) > (8) ? (d) : (8));
+            nuint i;
+
+            assert(ctx->nbTrainSamples >= 5);
+            assert(ctx->nbTrainSamples <= ctx->nbSamples);
+            for (i = 0; i < ctx->nbTrainSamples; i++)
+            {
+                nuint start = ctx->offsets[i];
+                nuint currSampleEnd = ctx->offsets[i + 1];
+
+                while (start + readLength <= currSampleEnd)
+                {
+                    nuint dmerIndex = FASTCOVER_hashPtrToIndex((void*)(ctx->samples + start), f, d);
+
+                    freqs[dmerIndex]++;
+                    start = start + skip + 1;
+                }
+            }
+        }
+
+        /**
+         * Prepare a context for dictionary building.
+         * The context is only dependent on the parameter `d` and can used multiple
+         * times.
+         * Returns 0 on success or error code on error.
+         * The context must be destroyed with `FASTCOVER_ctx_destroy()`.
+         */
+        private static nuint FASTCOVER_ctx_init(FASTCOVER_ctx_t* ctx, void* samplesBuffer, nuint* samplesSizes, uint nbSamples, uint d, double splitPoint, uint f, FASTCOVER_accel_t accelParams)
+        {
+            byte* samples = (byte*)(samplesBuffer);
+            nuint totalSamplesSize = COVER_sum(samplesSizes, nbSamples);
+            uint nbTrainSamples = splitPoint < 1.0 ? (uint)((double)(nbSamples) * splitPoint) : nbSamples;
+            uint nbTestSamples = splitPoint < 1.0 ? nbSamples - nbTrainSamples : nbSamples;
+            nuint trainingSamplesSize = splitPoint < 1.0 ? COVER_sum(samplesSizes, nbTrainSamples) : totalSamplesSize;
+            nuint testSamplesSize = splitPoint < 1.0 ? COVER_sum(samplesSizes + nbTrainSamples, nbTestSamples) : totalSamplesSize;
+
+            if (totalSamplesSize < ((d) > ((nuint)(sizeof(ulong))) ? (d) : ((nuint)(sizeof(ulong)))) || totalSamplesSize >= (nuint)((nuint)(sizeof(nuint)) == 8 ? (unchecked((uint)(-1))) : ((uint)(1) * (1U << 30))))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong)));
+            }
+
+            if (nbTrainSamples < 5)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong)));
+            }
+
+            if (nbTestSamples < 1)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong)));
+            }
+
+            memset((void*)ctx, 0, (nuint)(sizeof(FASTCOVER_ctx_t)));
+            ctx->samples = samples;
+            ctx->samplesSizes = samplesSizes;
+            ctx->nbSamples = nbSamples;
+            ctx->nbTrainSamples = nbTrainSamples;
+            ctx->nbTestSamples = nbTestSamples;
+            ctx->nbDmers = trainingSamplesSize - ((d) > ((nuint)(sizeof(ulong))) ? (d) : ((nuint)(sizeof(ulong)))) + 1;
+            ctx->d = d;
+            ctx->f = f;
+            ctx->accelParams = accelParams;
+            ctx->offsets = (nuint*)(calloc((nbSamples + 1), (nuint)(sizeof(nuint))));
+            if (ctx->offsets == null)
+            {
+                FASTCOVER_ctx_destroy(ctx);
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_memory_allocation)));
+            }
+
+
+            {
+                uint i;
+
+                ctx->offsets[0] = 0;
+                assert(nbSamples >= 5);
+                for (i = 1; i <= nbSamples; ++i)
+                {
+                    ctx->offsets[i] = ctx->offsets[i - 1] + samplesSizes[i - 1];
+                }
+            }
+
+            ctx->freqs = (uint*)(calloc((nuint)((ulong)(1) << (int)f), (nuint)(sizeof(uint))));
+            if (ctx->freqs == null)
+            {
+                FASTCOVER_ctx_destroy(ctx);
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_memory_allocation)));
+            }
+
+            FASTCOVER_computeFrequency(ctx->freqs, ctx);
+            return 0;
+        }
+
+        /**
+         * Given the prepared context build the dictionary.
+         */
+        private static nuint FASTCOVER_buildDictionary(FASTCOVER_ctx_t* ctx, uint* freqs, void* dictBuffer, nuint dictBufferCapacity, ZDICT_cover_params_t parameters, ushort* segmentFreqs)
+        {
+            byte* dict = (byte*)(dictBuffer);
+            nuint tail = dictBufferCapacity;
+            COVER_epoch_info_t epochs = COVER_computeEpochs((uint)(dictBufferCapacity), (uint)(ctx->nbDmers), parameters.k, 1);
+            nuint maxZeroScoreRun = 10;
+            nuint zeroScoreRun = 0;
+            nuint epoch;
+
+            for (epoch = 0; tail > 0; epoch = (nuint)((epoch + 1) % epochs.num))
+            {
+                uint epochBegin = (uint)(epoch * epochs.size);
+                uint epochEnd = epochBegin + epochs.size;
+                nuint segmentSize;
+                COVER_segment_t segment = FASTCOVER_selectSegment(ctx, freqs, epochBegin, epochEnd, parameters, segmentFreqs);
+
+                if (segment.score == 0)
+                {
+                    if (++zeroScoreRun >= maxZeroScoreRun)
+                    {
+                        break;
+                    }
+
+                    continue;
+                }
+
+                zeroScoreRun = 0;
+                segmentSize = ((segment.end - segment.begin + parameters.d - 1) < (tail) ? (segment.end - segment.begin + parameters.d - 1) : (tail));
+                if (segmentSize < parameters.d)
+                {
+                    break;
+                }
+
+                tail -= segmentSize;
+                memcpy((void*)(dict + tail), (void*)(ctx->samples + segment.begin), segmentSize);
+            }
+
+            return tail;
+        }
+
+        /**
+         * Tries a set of parameters and updates the COVER_best_t with the results.
+         * This function is thread safe if zstd is compiled with multithreaded support.
+         * It takes its parameters as an *OWNING* opaque pointer to support threading.
+         */
+        private static void FASTCOVER_tryParameters(void* opaque)
+        {
+            FASTCOVER_tryParameters_data_s* data = (FASTCOVER_tryParameters_data_s*)(opaque);
+            FASTCOVER_ctx_t* ctx = data->ctx;
+            ZDICT_cover_params_t parameters = data->parameters;
+            nuint dictBufferCapacity = data->dictBufferCapacity;
+            nuint totalCompressedSize = (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            ushort* segmentFreqs = (ushort*)(calloc((nuint)((ulong)(1) << (int)ctx->f), (nuint)(2)));
+            byte* dict = (byte*)(malloc(dictBufferCapacity));
+            COVER_dictSelection selection = COVER_dictSelectionError((unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC))));
+            uint* freqs = (uint*)(malloc((nuint)(((ulong)(1) << (int)ctx->f) * (nuint)(4))));
+
+            if (segmentFreqs == null || dict == null || freqs == null)
+            {
+                goto _cleanup;
+            }
+
+            memcpy((void*)freqs, (void*)ctx->freqs, (nuint)(((ulong)(1) << (int)ctx->f) * (nuint)(sizeof(uint))));
+
+            {
+                nuint tail = FASTCOVER_buildDictionary(ctx, freqs, (void*)dict, dictBufferCapacity, parameters, segmentFreqs);
+                uint nbFinalizeSamples = (uint)(ctx->nbTrainSamples * ctx->accelParams.finalize / 100);
+
+                selection = COVER_selectDict(dict + tail, dictBufferCapacity, dictBufferCapacity - tail, ctx->samples, ctx->samplesSizes, nbFinalizeSamples, ctx->nbTrainSamples, ctx->nbSamples, parameters, ctx->offsets, totalCompressedSize);
+                if ((COVER_dictSelectionIsError(selection)) != 0)
+                {
+                    goto _cleanup;
+                }
+            }
+
+            _cleanup:
+            free((void*)dict);
+            COVER_best_finish(data->best, parameters, selection);
+            free((void*)data);
+            free((void*)segmentFreqs);
+            COVER_dictSelectionFree(selection);
+            free((void*)freqs);
+        }
+
+        private static void FASTCOVER_convertToCoverParams(ZDICT_fastCover_params_t fastCoverParams, ZDICT_cover_params_t* coverParams)
+        {
+            coverParams->k = fastCoverParams.k;
+            coverParams->d = fastCoverParams.d;
+            coverParams->steps = fastCoverParams.steps;
+            coverParams->nbThreads = fastCoverParams.nbThreads;
+            coverParams->splitPoint = fastCoverParams.splitPoint;
+            coverParams->zParams = fastCoverParams.zParams;
+            coverParams->shrinkDict = fastCoverParams.shrinkDict;
+        }
+
+        private static void FASTCOVER_convertToFastCoverParams(ZDICT_cover_params_t coverParams, ZDICT_fastCover_params_t* fastCoverParams, uint f, uint accel)
+        {
+            fastCoverParams->k = coverParams.k;
+            fastCoverParams->d = coverParams.d;
+            fastCoverParams->steps = coverParams.steps;
+            fastCoverParams->nbThreads = coverParams.nbThreads;
+            fastCoverParams->splitPoint = coverParams.splitPoint;
+            fastCoverParams->f = f;
+            fastCoverParams->accel = accel;
+            fastCoverParams->zParams = coverParams.zParams;
+            fastCoverParams->shrinkDict = coverParams.shrinkDict;
+        }
+
+        /*! ZDICT_trainFromBuffer_fastCover():
+         *  Train a dictionary from an array of samples using a modified version of COVER algorithm.
+         *  Samples must be stored concatenated in a single flat buffer `samplesBuffer`,
+         *  supplied with an array of sizes `samplesSizes`, providing the size of each sample, in order.
+         *  d and k are required.
+         *  All other parameters are optional, will use default values if not provided
+         *  The resulting dictionary will be saved into `dictBuffer`.
+         * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)
+         *          or an error code, which can be tested with ZDICT_isError().
+         *          See ZDICT_trainFromBuffer() for details on failure modes.
+         *  Note: ZDICT_trainFromBuffer_fastCover() requires 6 * 2^f bytes of memory.
+         *  Tips: In general, a reasonable dictionary has a size of ~ 100 KB.
+         *        It's possible to select smaller or larger size, just by specifying `dictBufferCapacity`.
+         *        In general, it's recommended to provide a few thousands samples, though this can vary a lot.
+         *        It's recommended that total size of all samples be about ~x100 times the target size of dictionary.
+         */
+        public static nuint ZDICT_trainFromBuffer_fastCover(void* dictBuffer, nuint dictBufferCapacity, void* samplesBuffer, nuint* samplesSizes, uint nbSamples, ZDICT_fastCover_params_t parameters)
+        {
+            byte* dict = (byte*)(dictBuffer);
+            FASTCOVER_ctx_t ctx;
+            ZDICT_cover_params_t coverParams;
+            FASTCOVER_accel_t accelParams;
+
+            g_displayLevel = (int)parameters.zParams.notificationLevel;
+            parameters.splitPoint = 1.0;
+            parameters.f = (uint)(parameters.f == 0 ? 20 : parameters.f);
+            parameters.accel = (uint)(parameters.accel == 0 ? 1 : parameters.accel);
+            memset((void*)&coverParams, 0, (nuint)(sizeof(ZDICT_cover_params_t)));
+            FASTCOVER_convertToCoverParams(parameters, &coverParams);
+            if ((FASTCOVER_checkParameters(coverParams, dictBufferCapacity, parameters.f, parameters.accel)) == 0)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_parameter_outOfBound)));
+            }
+
+            if (nbSamples == 0)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong)));
+            }
+
+            if (dictBufferCapacity < 256)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall)));
+            }
+
+            accelParams = FASTCOVER_defaultAccelParameters[parameters.accel];
+
+            {
+                nuint initVal = FASTCOVER_ctx_init(&ctx, samplesBuffer, samplesSizes, nbSamples, coverParams.d, parameters.splitPoint, parameters.f, accelParams);
+
+                if ((ERR_isError(initVal)) != 0)
+                {
+                    return initVal;
+                }
+            }
+
+            COVER_warnOnSmallCorpus(dictBufferCapacity, ctx.nbDmers, g_displayLevel);
+
+            {
+                ushort* segmentFreqs = (ushort*)(calloc((nuint)((ulong)(1) << (int)parameters.f), (nuint)(2)));
+                nuint tail = FASTCOVER_buildDictionary(&ctx, ctx.freqs, dictBuffer, dictBufferCapacity, coverParams, segmentFreqs);
+                uint nbFinalizeSamples = (uint)(ctx.nbTrainSamples * ctx.accelParams.finalize / 100);
+                nuint dictionarySize = ZDICT_finalizeDictionary((void*)dict, dictBufferCapacity, (void*)(dict + tail), dictBufferCapacity - tail, samplesBuffer, samplesSizes, nbFinalizeSamples, coverParams.zParams);
+
+                if ((ERR_isError(dictionarySize)) == 0)
+                {
+        ;
+                }
+
+                FASTCOVER_ctx_destroy(&ctx);
+                free((void*)segmentFreqs);
+                return dictionarySize;
+            }
+        }
+
+        /*! ZDICT_optimizeTrainFromBuffer_fastCover():
+         * The same requirements as above hold for all the parameters except `parameters`.
+         * This function tries many parameter combinations (specifically, k and d combinations)
+         * and picks the best parameters. `*parameters` is filled with the best parameters found,
+         * dictionary constructed with those parameters is stored in `dictBuffer`.
+         * All of the parameters d, k, steps, f, and accel are optional.
+         * If d is non-zero then we don't check multiple values of d, otherwise we check d = {6, 8}.
+         * if steps is zero it defaults to its default value.
+         * If k is non-zero then we don't check multiple values of k, otherwise we check steps values in [50, 2000].
+         * If f is zero, default value of 20 is used.
+         * If accel is zero, default value of 1 is used.
+         *
+         * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)
+         *          or an error code, which can be tested with ZDICT_isError().
+         *          On success `*parameters` contains the parameters selected.
+         *          See ZDICT_trainFromBuffer() for details on failure modes.
+         * Note: ZDICT_optimizeTrainFromBuffer_fastCover() requires about 6 * 2^f bytes of memory for each thread.
+         */
+        public static nuint ZDICT_optimizeTrainFromBuffer_fastCover(void* dictBuffer, nuint dictBufferCapacity, void* samplesBuffer, nuint* samplesSizes, uint nbSamples, ZDICT_fastCover_params_t* parameters)
+        {
+            ZDICT_cover_params_t coverParams;
+            FASTCOVER_accel_t accelParams;
+            uint nbThreads = parameters->nbThreads;
+            double splitPoint = parameters->splitPoint <= 0.0 ? 0.75 : parameters->splitPoint;
+            uint kMinD = (uint)(parameters->d == 0 ? 6 : parameters->d);
+            uint kMaxD = (uint)(parameters->d == 0 ? 8 : parameters->d);
+            uint kMinK = (uint)(parameters->k == 0 ? 50 : parameters->k);
+            uint kMaxK = (uint)(parameters->k == 0 ? 2000 : parameters->k);
+            uint kSteps = (uint)(parameters->steps == 0 ? 40 : parameters->steps);
+            uint kStepSize = (((kMaxK - kMinK) / kSteps) > (1) ? ((kMaxK - kMinK) / kSteps) : (1));
+            uint kIterations = (1 + (kMaxD - kMinD) / 2) * (1 + (kMaxK - kMinK) / kStepSize);
+            uint f = (uint)(parameters->f == 0 ? 20 : parameters->f);
+            uint accel = (uint)(parameters->accel == 0 ? 1 : parameters->accel);
+            uint shrinkDict = 0;
+            int displayLevel = (int)parameters->zParams.notificationLevel;
+            uint iteration = 1;
+            uint d;
+            uint k;
+            COVER_best_s best;
+            int warned = 0;
+
+            if (splitPoint <= 0 || splitPoint > 1)
+            {
+                if (displayLevel >= 1)
+                {
+        ;
+                }
+
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_parameter_outOfBound)));
+            }
+
+            if (accel == 0 || accel > 10)
+            {
+                if (displayLevel >= 1)
+                {
+        ;
+                }
+
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_parameter_outOfBound)));
+            }
+
+            if (kMinK < kMaxD || kMaxK < kMinK)
+            {
+                if (displayLevel >= 1)
+                {
+        ;
+                }
+
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_parameter_outOfBound)));
+            }
+
+            if (nbSamples == 0)
+            {
+                if (displayLevel >= 1)
+                {
+        ;
+                }
+
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong)));
+            }
+
+            if (dictBufferCapacity < 256)
+            {
+                if (displayLevel >= 1)
+                {
+        ;
+                }
+
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall)));
+            }
+
+            if (nbThreads > 1)
+            {
+                throw new NotImplementedException("Multiple threads are not supported");
+            }
+
+            COVER_best_init(&best);
+            memset((void*)&coverParams, 0, (nuint)(sizeof(ZDICT_cover_params_t)));
+            FASTCOVER_convertToCoverParams(*parameters, &coverParams);
+            accelParams = FASTCOVER_defaultAccelParameters[accel];
+            g_displayLevel = displayLevel == 0 ? 0 : displayLevel - 1;
+            if (displayLevel >= 2)
+            {
+        ;
+            }
+
+            for (d = kMinD; d <= kMaxD; d += 2)
+            {
+                FASTCOVER_ctx_t ctx;
+
+                if (displayLevel >= 3)
+                {
+        ;
+                }
+
+
+                {
+                    nuint initVal = FASTCOVER_ctx_init(&ctx, samplesBuffer, samplesSizes, nbSamples, d, splitPoint, f, accelParams);
+
+                    if ((ERR_isError(initVal)) != 0)
+                    {
+                        if (displayLevel >= 1)
+                        {
+        ;
+                        }
+
+                        COVER_best_destroy(&best);
+                        return initVal;
+                    }
+                }
+
+                if (warned == 0)
+                {
+                    COVER_warnOnSmallCorpus(dictBufferCapacity, ctx.nbDmers, displayLevel);
+                    warned = 1;
+                }
+
+                for (k = kMinK; k <= kMaxK; k += kStepSize)
+                {
+                    FASTCOVER_tryParameters_data_s* data = (FASTCOVER_tryParameters_data_s*)(malloc((nuint)(sizeof(FASTCOVER_tryParameters_data_s))));
+
+                    if (displayLevel >= 3)
+                    {
+        ;
+                    }
+
+                    if (data == null)
+                    {
+                        if (displayLevel >= 1)
+                        {
+        ;
+                        }
+
+                        COVER_best_destroy(&best);
+                        FASTCOVER_ctx_destroy(&ctx);
+                        return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_memory_allocation)));
+                    }
+
+                    data->ctx = &ctx;
+                    data->best = &best;
+                    data->dictBufferCapacity = dictBufferCapacity;
+                    data->parameters = coverParams;
+                    data->parameters.k = k;
+                    data->parameters.d = d;
+                    data->parameters.splitPoint = splitPoint;
+                    data->parameters.steps = kSteps;
+                    data->parameters.shrinkDict = shrinkDict;
+                    data->parameters.zParams.notificationLevel = (uint)g_displayLevel;
+                    if ((FASTCOVER_checkParameters(data->parameters, dictBufferCapacity, data->ctx->f, accel)) == 0)
+                    {
+                        free((void*)data);
+                        continue;
+                    }
+
+                    COVER_best_start(&best);
+                    FASTCOVER_tryParameters((void*)data);
+
+                    ++iteration;
+                }
+
+                COVER_best_wait(&best);
+                FASTCOVER_ctx_destroy(&ctx);
+            }
+
+            if (displayLevel >= 2)
+            {
+        ;
+            }
+
+
+            {
+                nuint dictSize = best.dictSize;
+
+                if ((ERR_isError(best.compressedSize)) != 0)
+                {
+                    nuint compressedSize = best.compressedSize;
+
+                    COVER_best_destroy(&best);
+                    return compressedSize;
+                }
+
+                FASTCOVER_convertToFastCoverParams(best.parameters, parameters, f, accel);
+                memcpy(dictBuffer, best.dict, dictSize);
+                COVER_best_destroy(&best);
+                return dictSize;
+            }
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/Fse.cs

@@ -0,0 +1,158 @@
+using System;
+using System.Runtime.CompilerServices;
+using static ZstdSharp.UnsafeHelper;
+
+namespace ZstdSharp.Unsafe
+{
+    public static unsafe partial class Methods
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void FSE_initCState(FSE_CState_t* statePtr, uint* ct)
+        {
+            void* ptr = (void*)ct;
+            ushort* u16ptr = (ushort*)(ptr);
+            uint tableLog = MEM_read16(ptr);
+
+            statePtr->value = (nint)(1) << (int)tableLog;
+            statePtr->stateTable = u16ptr + 2;
+            statePtr->symbolTT = ct + 1 + (tableLog != 0 ? (1 << (int)(tableLog - 1)) : 1);
+            statePtr->stateLog = tableLog;
+        }
+
+        /*! FSE_initCState2() :
+        *   Same as FSE_initCState(), but the first symbol to include (which will be the last to be read)
+        *   uses the smallest state value possible, saving the cost of this symbol */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void FSE_initCState2(FSE_CState_t* statePtr, uint* ct, uint symbol)
+        {
+            FSE_initCState(statePtr, ct);
+
+            {
+                FSE_symbolCompressionTransform symbolTT = ((FSE_symbolCompressionTransform*)(statePtr->symbolTT))[symbol];
+                ushort* stateTable = (ushort*)(statePtr->stateTable);
+                uint nbBitsOut = (uint)((symbolTT.deltaNbBits + (uint)((1 << 15))) >> 16);
+
+                statePtr->value = (nint)((nbBitsOut << 16) - symbolTT.deltaNbBits);
+                statePtr->value = (nint)(stateTable[(statePtr->value >> (int)nbBitsOut) + symbolTT.deltaFindState]);
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void FSE_encodeSymbol(BIT_CStream_t* bitC, FSE_CState_t* statePtr, uint symbol)
+        {
+            FSE_symbolCompressionTransform symbolTT = ((FSE_symbolCompressionTransform*)(statePtr->symbolTT))[symbol];
+            ushort* stateTable = (ushort*)(statePtr->stateTable);
+            uint nbBitsOut = (uint)(((nuint)statePtr->value + symbolTT.deltaNbBits) >> 16);
+
+            BIT_addBits(bitC, (nuint)statePtr->value, nbBitsOut);
+            statePtr->value = (nint)(stateTable[(statePtr->value >> (int)nbBitsOut) + symbolTT.deltaFindState]);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void FSE_flushCState(BIT_CStream_t* bitC, FSE_CState_t* statePtr)
+        {
+            BIT_addBits(bitC, (nuint)statePtr->value, statePtr->stateLog);
+            BIT_flushBits(bitC);
+        }
+
+        /* FSE_getMaxNbBits() :
+         * Approximate maximum cost of a symbol, in bits.
+         * Fractional get rounded up (i.e : a symbol with a normalized frequency of 3 gives the same result as a frequency of 2)
+         * note 1 : assume symbolValue is valid (<= maxSymbolValue)
+         * note 2 : if freq[symbolValue]==0, @return a fake cost of tableLog+1 bits */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint FSE_getMaxNbBits(void* symbolTTPtr, uint symbolValue)
+        {
+            FSE_symbolCompressionTransform* symbolTT = (FSE_symbolCompressionTransform*)(symbolTTPtr);
+
+            return (symbolTT[symbolValue].deltaNbBits + (uint)(((1 << 16) - 1))) >> 16;
+        }
+
+        /* FSE_bitCost() :
+         * Approximate symbol cost, as fractional value, using fixed-point format (accuracyLog fractional bits)
+         * note 1 : assume symbolValue is valid (<= maxSymbolValue)
+         * note 2 : if freq[symbolValue]==0, @return a fake cost of tableLog+1 bits */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint FSE_bitCost(void* symbolTTPtr, uint tableLog, uint symbolValue, uint accuracyLog)
+        {
+            FSE_symbolCompressionTransform* symbolTT = (FSE_symbolCompressionTransform*)(symbolTTPtr);
+            uint minNbBits = symbolTT[symbolValue].deltaNbBits >> 16;
+            uint threshold = (minNbBits + 1) << 16;
+
+            assert(tableLog < 16);
+            assert(accuracyLog < 31 - tableLog);
+
+            {
+                uint tableSize = (uint)(1 << (int)tableLog);
+                uint deltaFromThreshold = threshold - (symbolTT[symbolValue].deltaNbBits + tableSize);
+                uint normalizedDeltaFromThreshold = (deltaFromThreshold << (int)accuracyLog) >> (int)tableLog;
+                uint bitMultiplier = (uint)(1 << (int)accuracyLog);
+
+                assert(symbolTT[symbolValue].deltaNbBits + tableSize <= threshold);
+                assert(normalizedDeltaFromThreshold <= bitMultiplier);
+                return (minNbBits + 1) * bitMultiplier - normalizedDeltaFromThreshold;
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void FSE_initDState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD, uint* dt)
+        {
+            void* ptr = (void*)dt;
+            FSE_DTableHeader* DTableH = (FSE_DTableHeader*)(ptr);
+
+            DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog);
+            BIT_reloadDStream(bitD);
+            DStatePtr->table = dt + 1;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static byte FSE_peekSymbol(FSE_DState_t* DStatePtr)
+        {
+            FSE_decode_t DInfo = ((FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
+
+            return DInfo.symbol;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void FSE_updateState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD)
+        {
+            FSE_decode_t DInfo = ((FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
+            uint nbBits = DInfo.nbBits;
+            nuint lowBits = BIT_readBits(bitD, nbBits);
+
+            DStatePtr->state = DInfo.newState + lowBits;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static byte FSE_decodeSymbol(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD)
+        {
+            FSE_decode_t DInfo = ((FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
+            uint nbBits = DInfo.nbBits;
+            byte symbol = DInfo.symbol;
+            nuint lowBits = BIT_readBits(bitD, nbBits);
+
+            DStatePtr->state = DInfo.newState + lowBits;
+            return symbol;
+        }
+
+        /*! FSE_decodeSymbolFast() :
+            unsafe, only works if no symbol has a probability > 50% */
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static byte FSE_decodeSymbolFast(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD)
+        {
+            FSE_decode_t DInfo = ((FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
+            uint nbBits = DInfo.nbBits;
+            byte symbol = DInfo.symbol;
+            nuint lowBits = BIT_readBitsFast(bitD, nbBits);
+
+            DStatePtr->state = DInfo.newState + lowBits;
+            return symbol;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint FSE_endOfDState(FSE_DState_t* DStatePtr)
+        {
+            return ((DStatePtr->state == 0) ? 1U : 0U);
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FseCompress.cs

@@ -0,0 +1,960 @@
+using System;
+using static ZstdSharp.UnsafeHelper;
+
+namespace ZstdSharp.Unsafe
+{
+    public static unsafe partial class Methods
+    {
+        /* FSE_buildCTable_wksp() :
+         * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`).
+         * wkspSize should be sized to handle worst case situation, which is `1<<max_tableLog * sizeof(FSE_FUNCTION_TYPE)`
+         * workSpace must also be properly aligned with FSE_FUNCTION_TYPE requirements
+         */
+        public static nuint FSE_buildCTable_wksp(uint* ct, short* normalizedCounter, uint maxSymbolValue, uint tableLog, void* workSpace, nuint wkspSize)
+        {
+            uint tableSize = (uint)(1 << (int)tableLog);
+            uint tableMask = tableSize - 1;
+            void* ptr = (void*)ct;
+            ushort* tableU16 = ((ushort*)(ptr)) + 2;
+            void* FSCT = (void*)(((uint*)(ptr)) + 1 + (tableLog != 0 ? tableSize >> 1 : 1));
+            FSE_symbolCompressionTransform* symbolTT = (FSE_symbolCompressionTransform*)(FSCT);
+            uint step = (((tableSize) >> 1) + ((tableSize) >> 3) + 3);
+            uint* cumul = (uint*)(workSpace);
+            byte* tableSymbol = (byte*)(cumul + (maxSymbolValue + 2));
+            uint highThreshold = tableSize - 1;
+
+            if (((nuint)(workSpace) & 3) != 0)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            }
+
+            if (((nuint)(sizeof(uint)) * (maxSymbolValue + 2 + (1UL << (int)(tableLog - 2)))) > wkspSize)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge)));
+            }
+
+            tableU16[-2] = (ushort)(tableLog);
+            tableU16[-1] = (ushort)(maxSymbolValue);
+            assert(tableLog < 16);
+
+            {
+                uint u;
+
+                cumul[0] = 0;
+                for (u = 1; u <= maxSymbolValue + 1; u++)
+                {
+                    if (normalizedCounter[u - 1] == -1)
+                    {
+                        cumul[u] = cumul[u - 1] + 1;
+                        tableSymbol[highThreshold--] = (byte)(u - 1);
+                    }
+                    else
+                    {
+                        cumul[u] = cumul[u - 1] + (ushort)(normalizedCounter[u - 1]);
+                    }
+                }
+
+                cumul[maxSymbolValue + 1] = tableSize + 1;
+            }
+
+
+            {
+                uint position = 0;
+                uint symbol;
+
+                for (symbol = 0; symbol <= maxSymbolValue; symbol++)
+                {
+                    int nbOccurrences;
+                    int freq = normalizedCounter[symbol];
+
+                    for (nbOccurrences = 0; nbOccurrences < freq; nbOccurrences++)
+                    {
+                        tableSymbol[position] = (byte)(symbol);
+                        position = (position + step) & tableMask;
+                        while (position > highThreshold)
+                        {
+                            position = (position + step) & tableMask;
+                        }
+                    }
+                }
+
+                assert(position == 0);
+            }
+
+
+            {
+                uint u;
+
+                for (u = 0; u < tableSize; u++)
+                {
+                    byte s = tableSymbol[u];
+
+                    tableU16[cumul[s]++] = (ushort)(tableSize + u);
+                }
+            }
+
+
+            {
+                uint total = 0;
+                uint s;
+
+                for (s = 0; s <= maxSymbolValue; s++)
+                {
+                    switch (normalizedCounter[s])
+                    {
+                        case 0:
+                        {
+                            symbolTT[s].deltaNbBits = ((tableLog + 1) << 16) - (uint)((1 << (int)tableLog));
+                        }
+
+                        break;
+                        case -1:
+                        case 1:
+                        {
+                            symbolTT[s].deltaNbBits = (tableLog << 16) - (uint)((1 << (int)tableLog));
+                        }
+
+                        symbolTT[s].deltaFindState = (int)(total - 1);
+                        total++;
+                        break;
+                        default:
+                        {
+                            uint maxBitsOut = tableLog - BIT_highbit32((uint)(normalizedCounter[s] - 1));
+                            uint minStatePlus = (uint)(normalizedCounter[s] << (int)maxBitsOut);
+
+                            symbolTT[s].deltaNbBits = (maxBitsOut << 16) - minStatePlus;
+                            symbolTT[s].deltaFindState = (int)(total - (ushort)(normalizedCounter[s]));
+                            total += (uint)(normalizedCounter[s]);
+                        }
+                        break;
+                    }
+                }
+            }
+
+            return 0;
+        }
+
+        /*! FSE_buildCTable():
+            Builds `ct`, which must be already allocated, using FSE_createCTable().
+            @return : 0, or an errorCode, which can be tested using FSE_isError() */
+        public static nuint FSE_buildCTable(uint* ct, short* normalizedCounter, uint maxSymbolValue, uint tableLog)
+        {
+            byte* tableSymbol = stackalloc byte[4096];
+
+            return FSE_buildCTable_wksp(ct, normalizedCounter, maxSymbolValue, tableLog, (void*)tableSymbol, (nuint)(sizeof(byte) * 4096));
+        }
+
+        /*-**************************************************************
+        *  FSE NCount encoding
+        ****************************************************************/
+        public static nuint FSE_NCountWriteBound(uint maxSymbolValue, uint tableLog)
+        {
+            nuint maxHeaderSize = (((maxSymbolValue + 1) * tableLog) >> 3) + 3;
+
+            return maxSymbolValue != 0 ? maxHeaderSize : 512;
+        }
+
+        private static nuint FSE_writeNCount_generic(void* header, nuint headerBufferSize, short* normalizedCounter, uint maxSymbolValue, uint tableLog, uint writeIsSafe)
+        {
+            byte* ostart = (byte*)(header);
+            byte* @out = ostart;
+            byte* oend = ostart + headerBufferSize;
+            int nbBits;
+            int tableSize = 1 << (int)tableLog;
+            int remaining;
+            int threshold;
+            uint bitStream = 0;
+            int bitCount = 0;
+            uint symbol = 0;
+            uint alphabetSize = maxSymbolValue + 1;
+            int previousIs0 = 0;
+
+            bitStream += (tableLog - 5) << bitCount;
+            bitCount += 4;
+            remaining = tableSize + 1;
+            threshold = tableSize;
+            nbBits = (int)(tableLog + 1);
+            while ((symbol < alphabetSize) && (remaining > 1))
+            {
+                if (previousIs0 != 0)
+                {
+                    uint start = symbol;
+
+                    while ((symbol < alphabetSize) && (normalizedCounter[symbol]) == 0)
+                    {
+                        symbol++;
+                    }
+
+                    if (symbol == alphabetSize)
+                    {
+                        break;
+                    }
+
+                    while (symbol >= start + 24)
+                    {
+                        start += 24;
+                        bitStream += 0xFFFFU << bitCount;
+                        if (writeIsSafe == 0 && (@out > oend - 2))
+                        {
+                            return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall)));
+                        }
+
+                        @out[0] = (byte)(bitStream);
+                        @out[1] = (byte)(bitStream >> 8);
+                        @out += 2;
+                        bitStream >>= 16;
+                    }
+
+                    while (symbol >= start + 3)
+                    {
+                        start += 3;
+                        bitStream += (uint)(3 << bitCount);
+                        bitCount += 2;
+                    }
+
+                    bitStream += (symbol - start) << bitCount;
+                    bitCount += 2;
+                    if (bitCount > 16)
+                    {
+                        if (writeIsSafe == 0 && (@out > oend - 2))
+                        {
+                            return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall)));
+                        }
+
+                        @out[0] = (byte)(bitStream);
+                        @out[1] = (byte)(bitStream >> 8);
+                        @out += 2;
+                        bitStream >>= 16;
+                        bitCount -= 16;
+                    }
+                }
+
+
+                {
+                    int count = normalizedCounter[symbol++];
+                    int max = (2 * threshold - 1) - remaining;
+
+                    remaining -= count < 0 ? -count : count;
+                    count++;
+                    if (count >= threshold)
+                    {
+                        count += max;
+                    }
+
+                    bitStream += (uint)(count << bitCount);
+                    bitCount += nbBits;
+                    bitCount -= ((count < max) ? 1 : 0);
+                    previousIs0 = ((count == 1) ? 1 : 0);
+                    if (remaining < 1)
+                    {
+                        return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+                    }
+
+                    while (remaining < threshold)
+                    {
+                        nbBits--;
+                        threshold >>= 1;
+                    }
+                }
+
+                if (bitCount > 16)
+                {
+                    if (writeIsSafe == 0 && (@out > oend - 2))
+                    {
+                        return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall)));
+                    }
+
+                    @out[0] = (byte)(bitStream);
+                    @out[1] = (byte)(bitStream >> 8);
+                    @out += 2;
+                    bitStream >>= 16;
+                    bitCount -= 16;
+                }
+            }
+
+            if (remaining != 1)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            }
+
+            assert(symbol <= alphabetSize);
+            if (writeIsSafe == 0 && (@out > oend - 2))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall)));
+            }
+
+            @out[0] = (byte)(bitStream);
+            @out[1] = (byte)(bitStream >> 8);
+            @out += (bitCount + 7) / 8;
+            return (nuint)((@out - ostart));
+        }
+
+        /*! FSE_writeNCount():
+            Compactly save 'normalizedCounter' into 'buffer'.
+            @return : size of the compressed table,
+                      or an errorCode, which can be tested using FSE_isError(). */
+        public static nuint FSE_writeNCount(void* buffer, nuint bufferSize, short* normalizedCounter, uint maxSymbolValue, uint tableLog)
+        {
+            if (tableLog > (uint)((14 - 2)))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge)));
+            }
+
+            if (tableLog < 5)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            }
+
+            if (bufferSize < FSE_NCountWriteBound(maxSymbolValue, tableLog))
+            {
+                return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 0);
+            }
+
+            return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 1);
+        }
+
+        /*-**************************************************************
+        *  FSE Compression Code
+        ****************************************************************/
+        public static uint* FSE_createCTable(uint maxSymbolValue, uint tableLog)
+        {
+            nuint size;
+
+            if (tableLog > 15)
+            {
+                tableLog = 15;
+            }
+
+            size = ((uint)(1 + (1 << (int)((tableLog) - 1))) + (((maxSymbolValue) + 1) * 2)) * (nuint)(sizeof(uint));
+            return (uint*)(malloc(size));
+        }
+
+        public static void FSE_freeCTable(uint* ct)
+        {
+            free((void*)(ct));
+        }
+
+        /* provides the minimum logSize to safely represent a distribution */
+        [InlineMethod.Inline]
+        private static uint FSE_minTableLog(nuint srcSize, uint maxSymbolValue)
+        {
+            uint minBitsSrc = BIT_highbit32((uint)(srcSize)) + 1;
+            uint minBitsSymbols = BIT_highbit32(maxSymbolValue) + 2;
+            uint minBits = minBitsSrc < minBitsSymbols ? minBitsSrc : minBitsSymbols;
+
+            assert(srcSize > 1);
+            return minBits;
+        }
+
+        /* *****************************************
+         *  FSE advanced API
+         ***************************************** */
+        public static uint FSE_optimalTableLog_internal(uint maxTableLog, nuint srcSize, uint maxSymbolValue, uint minus)
+        {
+            uint maxBitsSrc = BIT_highbit32((uint)(srcSize - 1)) - minus;
+            uint tableLog = maxTableLog;
+            uint minBits = FSE_minTableLog(srcSize, maxSymbolValue);
+
+            assert(srcSize > 1);
+            if (tableLog == 0)
+            {
+                tableLog = (uint)((13 - 2));
+            }
+
+            if (maxBitsSrc < tableLog)
+            {
+                tableLog = maxBitsSrc;
+            }
+
+            if (minBits > tableLog)
+            {
+                tableLog = minBits;
+            }
+
+            if (tableLog < 5)
+            {
+                tableLog = 5;
+            }
+
+            if (tableLog > (uint)((14 - 2)))
+            {
+                tableLog = (uint)((14 - 2));
+            }
+
+            return tableLog;
+        }
+
+        /*! FSE_optimalTableLog():
+            dynamically downsize 'tableLog' when conditions are met.
+            It saves CPU time, by using smaller tables, while preserving or even improving compression ratio.
+            @return : recommended tableLog (necessarily <= 'maxTableLog') */
+        public static uint FSE_optimalTableLog(uint maxTableLog, nuint srcSize, uint maxSymbolValue)
+        {
+            return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 2);
+        }
+
+        /* Secondary normalization method.
+           To be used when primary method fails. */
+        private static nuint FSE_normalizeM2(short* norm, uint tableLog, uint* count, nuint total, uint maxSymbolValue, short lowProbCount)
+        {
+            short NOT_YET_ASSIGNED = (short)-2;
+            uint s;
+            uint distributed = 0;
+            uint ToDistribute;
+            uint lowThreshold = (uint)(total >> (int)tableLog);
+            uint lowOne = (uint)((total * 3) >> (int)(tableLog + 1));
+
+            for (s = 0; s <= maxSymbolValue; s++)
+            {
+                if (count[s] == 0)
+                {
+                    norm[s] = 0;
+                    continue;
+                }
+
+                if (count[s] <= lowThreshold)
+                {
+                    norm[s] = lowProbCount;
+                    distributed++;
+                    total -= count[s];
+                    continue;
+                }
+
+                if (count[s] <= lowOne)
+                {
+                    norm[s] = 1;
+                    distributed++;
+                    total -= count[s];
+                    continue;
+                }
+
+                norm[s] = NOT_YET_ASSIGNED;
+            }
+
+            ToDistribute = (uint)((1 << (int)tableLog)) - distributed;
+            if (ToDistribute == 0)
+            {
+                return 0;
+            }
+
+            if ((total / ToDistribute) > lowOne)
+            {
+                lowOne = (uint)((total * 3) / (ToDistribute * 2));
+                for (s = 0; s <= maxSymbolValue; s++)
+                {
+                    if ((norm[s] == NOT_YET_ASSIGNED) && (count[s] <= lowOne))
+                    {
+                        norm[s] = 1;
+                        distributed++;
+                        total -= count[s];
+                        continue;
+                    }
+                }
+
+                ToDistribute = (uint)((1 << (int)tableLog)) - distributed;
+            }
+
+            if (distributed == maxSymbolValue + 1)
+            {
+                uint maxV = 0, maxC = 0;
+
+                for (s = 0; s <= maxSymbolValue; s++)
+                {
+                    if (count[s] > maxC)
+                    {
+                        maxV = s;
+                        maxC = count[s];
+                    }
+                }
+
+                norm[maxV] += (short)(short)(ToDistribute);
+                return 0;
+            }
+
+            if (total == 0)
+            {
+                for (s = 0; ToDistribute > 0; s = (s + 1) % (maxSymbolValue + 1))
+                {
+                    if (norm[s] > 0)
+                    {
+                        ToDistribute--;
+                        norm[s]++;
+                    }
+                }
+
+                return 0;
+            }
+
+
+            {
+                ulong vStepLog = 62 - tableLog;
+                ulong mid = (1UL << (int)(vStepLog - 1)) - 1;
+                ulong rStep = (((((ulong)(1) << (int)vStepLog) * ToDistribute) + mid) / ((uint)(total)));
+                ulong tmpTotal = mid;
+
+                for (s = 0; s <= maxSymbolValue; s++)
+                {
+                    if (norm[s] == NOT_YET_ASSIGNED)
+                    {
+                        ulong end = tmpTotal + (count[s] * rStep);
+                        uint sStart = (uint)(tmpTotal >> (int)vStepLog);
+                        uint sEnd = (uint)(end >> (int)vStepLog);
+                        uint weight = sEnd - sStart;
+
+                        if (weight < 1)
+                        {
+                            return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+                        }
+
+                        norm[s] = (short)(weight);
+                        tmpTotal = end;
+                    }
+                }
+            }
+
+            return 0;
+        }
+
+        /*! FSE_normalizeCount():
+            normalize counts so that sum(count[]) == Power_of_2 (2^tableLog)
+            'normalizedCounter' is a table of short, of minimum size (maxSymbolValue+1).
+            useLowProbCount is a boolean parameter which trades off compressed size for
+            faster header decoding. When it is set to 1, the compressed data will be slightly
+            smaller. And when it is set to 0, FSE_readNCount() and FSE_buildDTable() will be
+            faster. If you are compressing a small amount of data (< 2 KB) then useLowProbCount=0
+            is a good default, since header deserialization makes a big speed difference.
+            Otherwise, useLowProbCount=1 is a good default, since the speed difference is small.
+            @return : tableLog,
+                      or an errorCode, which can be tested using FSE_isError() */
+        public static nuint FSE_normalizeCount(short* normalizedCounter, uint tableLog, uint* count, nuint total, uint maxSymbolValue, uint useLowProbCount)
+        {
+            if (tableLog == 0)
+            {
+                tableLog = (uint)((13 - 2));
+            }
+
+            if (tableLog < 5)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            }
+
+            if (tableLog > (uint)((14 - 2)))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge)));
+            }
+
+            if (tableLog < FSE_minTableLog(total, maxSymbolValue))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            }
+
+
+            {
+
+                short lowProbCount = (short)(useLowProbCount != 0 ? -1 : 1);
+                ulong scale = 62 - tableLog;
+                ulong step = (((ulong)(1) << 62) / ((uint)(total)));
+                ulong vStep = 1UL << (int)(scale - 20);
+                int stillToDistribute = 1 << (int)tableLog;
+                uint s;
+                uint largest = 0;
+                short largestP = 0;
+                uint lowThreshold = (uint)(total >> (int)tableLog);
+
+                for (s = 0; s <= maxSymbolValue; s++)
+                {
+                    if (count[s] == total)
+                    {
+                        return 0;
+                    }
+
+                    if (count[s] == 0)
+                    {
+                        normalizedCounter[s] = 0;
+                        continue;
+                    }
+
+                    if (count[s] <= lowThreshold)
+                    {
+                        normalizedCounter[s] = lowProbCount;
+                        stillToDistribute--;
+                    }
+                    else
+                    {
+                        short proba = (short)((count[s] * step) >> (int)scale);
+
+                        if (proba < 8)
+                        {
+                            ulong restToBeat = vStep * rtbTable[proba];
+
+                            proba += (short)((((count[s] * step) - ((ulong)(proba) << (int)scale) > restToBeat) ? 1 : 0));
+                        }
+
+                        if (proba > largestP)
+                        {
+                            largestP = proba;
+                            largest = s;
+                        }
+
+                        normalizedCounter[s] = proba;
+                        stillToDistribute -= proba;
+                    }
+                }
+
+                if (-stillToDistribute >= (normalizedCounter[largest] >> 1))
+                {
+                    nuint errorCode = FSE_normalizeM2(normalizedCounter, tableLog, count, total, maxSymbolValue, lowProbCount);
+
+                    if ((ERR_isError(errorCode)) != 0)
+                    {
+                        return errorCode;
+                    }
+                }
+                else
+                {
+                    normalizedCounter[largest] += (short)(short)(stillToDistribute);
+                }
+            }
+
+            return tableLog;
+        }
+
+        /* fake FSE_CTable, for raw (uncompressed) input */
+        public static nuint FSE_buildCTable_raw(uint* ct, uint nbBits)
+        {
+            uint tableSize = (uint)(1 << (int)nbBits);
+            uint tableMask = tableSize - 1;
+            uint maxSymbolValue = tableMask;
+            void* ptr = (void*)ct;
+            ushort* tableU16 = ((ushort*)(ptr)) + 2;
+            void* FSCT = (void*)(((uint*)(ptr)) + 1 + (tableSize >> 1));
+            FSE_symbolCompressionTransform* symbolTT = (FSE_symbolCompressionTransform*)(FSCT);
+            uint s;
+
+            if (nbBits < 1)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            }
+
+            tableU16[-2] = (ushort)(nbBits);
+            tableU16[-1] = (ushort)(maxSymbolValue);
+            for (s = 0; s < tableSize; s++)
+            {
+                tableU16[s] = (ushort)(tableSize + s);
+            }
+
+
+            {
+                uint deltaNbBits = (nbBits << 16) - (uint)((1 << (int)nbBits));
+
+                for (s = 0; s <= maxSymbolValue; s++)
+                {
+                    symbolTT[s].deltaNbBits = deltaNbBits;
+                    symbolTT[s].deltaFindState = (int)(s - 1);
+                }
+            }
+
+            return 0;
+        }
+
+        /* fake FSE_CTable, for rle input (always same symbol) */
+        public static nuint FSE_buildCTable_rle(uint* ct, byte symbolValue)
+        {
+            void* ptr = (void*)ct;
+            ushort* tableU16 = ((ushort*)(ptr)) + 2;
+            void* FSCTptr = (void*)((uint*)(ptr) + 2);
+            FSE_symbolCompressionTransform* symbolTT = (FSE_symbolCompressionTransform*)(FSCTptr);
+
+            tableU16[-2] = (ushort)(0);
+            tableU16[-1] = (ushort)(symbolValue);
+            tableU16[0] = 0;
+            tableU16[1] = 0;
+            symbolTT[symbolValue].deltaNbBits = 0;
+            symbolTT[symbolValue].deltaFindState = 0;
+            return 0;
+        }
+
+        private static nuint FSE_compress_usingCTable_generic(void* dst, nuint dstSize, void* src, nuint srcSize, uint* ct, uint fast)
+        {
+            byte* istart = (byte*)(src);
+            byte* iend = istart + srcSize;
+            byte* ip = iend;
+            BIT_CStream_t bitC;
+            FSE_CState_t CState1, CState2;
+
+            if (srcSize <= 2)
+            {
+                return 0;
+            }
+
+
+            {
+                nuint initError = BIT_initCStream(&bitC, dst, dstSize);
+
+                if ((ERR_isError(initError)) != 0)
+                {
+                    return 0;
+                }
+            }
+
+            if ((srcSize & 1) != 0)
+            {
+                FSE_initCState2(&CState1, ct, *--ip);
+                FSE_initCState2(&CState2, ct, *--ip);
+                FSE_encodeSymbol(&bitC, &CState1, *--ip);
+                if (fast != 0)
+                {
+                    BIT_flushBitsFast(&bitC);
+                }
+                else
+                {
+                    BIT_flushBits(&bitC);
+                }
+
+            }
+            else
+            {
+                FSE_initCState2(&CState2, ct, *--ip);
+                FSE_initCState2(&CState1, ct, *--ip);
+            }
+
+            srcSize -= 2;
+            if (((nuint)(sizeof(nuint)) * 8 > (uint)((14 - 2) * 4 + 7)) && (srcSize & 2) != 0)
+            {
+                FSE_encodeSymbol(&bitC, &CState2, *--ip);
+                FSE_encodeSymbol(&bitC, &CState1, *--ip);
+                if (fast != 0)
+                {
+                    BIT_flushBitsFast(&bitC);
+                }
+                else
+                {
+                    BIT_flushBits(&bitC);
+                }
+
+            }
+
+            while (ip > istart)
+            {
+                FSE_encodeSymbol(&bitC, &CState2, *--ip);
+                if ((nuint)(sizeof(nuint)) * 8 < (uint)((14 - 2) * 2 + 7))
+                {
+                    if (fast != 0)
+                    {
+                        BIT_flushBitsFast(&bitC);
+                    }
+                    else
+                    {
+                        BIT_flushBits(&bitC);
+                    }
+                }
+
+                FSE_encodeSymbol(&bitC, &CState1, *--ip);
+                if ((nuint)(sizeof(nuint)) * 8 > (uint)((14 - 2) * 4 + 7))
+                {
+                    FSE_encodeSymbol(&bitC, &CState2, *--ip);
+                    FSE_encodeSymbol(&bitC, &CState1, *--ip);
+                }
+
+                if (fast != 0)
+                {
+                    BIT_flushBitsFast(&bitC);
+                }
+                else
+                {
+                    BIT_flushBits(&bitC);
+                }
+
+            }
+
+            FSE_flushCState(&bitC, &CState2);
+            FSE_flushCState(&bitC, &CState1);
+            return BIT_closeCStream(&bitC);
+        }
+
+        /*! FSE_compress_usingCTable():
+            Compress `src` using `ct` into `dst` which must be already allocated.
+            @return : size of compressed data (<= `dstCapacity`),
+                      or 0 if compressed data could not fit into `dst`,
+                      or an errorCode, which can be tested using FSE_isError() */
+        public static nuint FSE_compress_usingCTable(void* dst, nuint dstSize, void* src, nuint srcSize, uint* ct)
+        {
+            uint fast = (((dstSize >= ((srcSize) + ((srcSize) >> 7) + 4 + (nuint)(sizeof(nuint))))) ? 1U : 0U);
+
+            if (fast != 0)
+            {
+                return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 1);
+            }
+            else
+            {
+                return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 0);
+            }
+        }
+
+        /*-*****************************************
+        *  Tool functions
+        ******************************************/
+        public static nuint FSE_compressBound(nuint size)
+        {
+            return (512 + ((size) + ((size) >> 7) + 4 + (nuint)(sizeof(nuint))));
+        }
+
+        /* FSE_compress_wksp() :
+         * Same as FSE_compress2(), but using an externally allocated scratch buffer (`workSpace`).
+         * `wkspSize` size must be `(1<<tableLog)`.
+         */
+        public static nuint FSE_compress_wksp(void* dst, nuint dstSize, void* src, nuint srcSize, uint maxSymbolValue, uint tableLog, void* workSpace, nuint wkspSize)
+        {
+            byte* ostart = (byte*)(dst);
+            byte* op = ostart;
+            byte* oend = ostart + dstSize;
+            uint* count = stackalloc uint[256];
+            short* norm = stackalloc short[256];
+            uint* CTable = (uint*)(workSpace);
+            nuint CTableSize = ((uint)(1 + (1 << (int)((tableLog) - 1))) + (((maxSymbolValue) + 1) * 2));
+            void* scratchBuffer = (void*)(CTable + CTableSize);
+            nuint scratchBufferSize = wkspSize - (CTableSize * (nuint)(4));
+
+            if (wkspSize < (((uint)(1 + (1 << (int)((tableLog) - 1))) + (((maxSymbolValue) + 1) * 2)) + (uint)(((tableLog > 12) ? (1 << (int)(tableLog - 2)) : 1024))))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge)));
+            }
+
+            if (srcSize <= 1)
+            {
+                return 0;
+            }
+
+            if (maxSymbolValue == 0)
+            {
+                maxSymbolValue = 255;
+            }
+
+            if (tableLog == 0)
+            {
+                tableLog = (uint)((13 - 2));
+            }
+
+
+            {
+                nuint maxCount = HIST_count_wksp((uint*)count, &maxSymbolValue, src, srcSize, scratchBuffer, scratchBufferSize);
+
+                if ((ERR_isError(maxCount)) != 0)
+                {
+                    return maxCount;
+                }
+
+                if (maxCount == srcSize)
+                {
+                    return 1;
+                }
+
+                if (maxCount == 1)
+                {
+                    return 0;
+                }
+
+                if (maxCount < (srcSize >> 7))
+                {
+                    return 0;
+                }
+            }
+
+            tableLog = FSE_optimalTableLog(tableLog, srcSize, maxSymbolValue);
+
+            {
+                nuint _var_err__ = FSE_normalizeCount((short*)norm, tableLog, (uint*)count, srcSize, maxSymbolValue, ((srcSize >= 2048) ? 1U : 0U));
+
+                if ((ERR_isError(_var_err__)) != 0)
+                {
+                    return _var_err__;
+                }
+            }
+
+
+            {
+                nuint nc_err = FSE_writeNCount((void*)op, (nuint)(oend - op), (short*)norm, maxSymbolValue, tableLog);
+
+                if ((ERR_isError(nc_err)) != 0)
+                {
+                    return nc_err;
+                }
+
+                op += nc_err;
+            }
+
+
+            {
+                nuint _var_err__ = FSE_buildCTable_wksp(CTable, (short*)norm, maxSymbolValue, tableLog, scratchBuffer, scratchBufferSize);
+
+                if ((ERR_isError(_var_err__)) != 0)
+                {
+                    return _var_err__;
+                }
+            }
+
+
+            {
+                nuint cSize = FSE_compress_usingCTable((void*)op, (nuint)(oend - op), src, srcSize, CTable);
+
+                if ((ERR_isError(cSize)) != 0)
+                {
+                    return cSize;
+                }
+
+                if (cSize == 0)
+                {
+                    return 0;
+                }
+
+                op += cSize;
+            }
+
+            if ((nuint)(op - ostart) >= srcSize - 1)
+            {
+                return 0;
+            }
+
+            return (nuint)(op - ostart);
+        }
+
+        /*-*****************************************
+        *  FSE advanced functions
+        ******************************************/
+        /*! FSE_compress2() :
+            Same as FSE_compress(), but allows the selection of 'maxSymbolValue' and 'tableLog'
+            Both parameters can be defined as '0' to mean : use default value
+            @return : size of compressed data
+            Special values : if return == 0, srcData is not compressible => Nothing is stored within cSrc !!!
+                             if return == 1, srcData is a single byte symbol * srcSize times. Use RLE compression.
+                             if FSE_isError(return), it's an error code.
+        */
+        public static nuint FSE_compress2(void* dst, nuint dstCapacity, void* src, nuint srcSize, uint maxSymbolValue, uint tableLog)
+        {
+            fseWkspMax_t scratchBuffer;
+
+            if (tableLog > (uint)((14 - 2)))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge)));
+            }
+
+            return FSE_compress_wksp(dst, dstCapacity, src, srcSize, maxSymbolValue, tableLog, (void*)&scratchBuffer, (nuint)(sizeof(fseWkspMax_t)));
+        }
+
+        /*-****************************************
+        *  FSE simple functions
+        ******************************************/
+        /*! FSE_compress() :
+            Compress content of buffer 'src', of size 'srcSize', into destination buffer 'dst'.
+            'dst' buffer must be already allocated. Compression runs faster is dstCapacity >= FSE_compressBound(srcSize).
+            @return : size of compressed data (<= dstCapacity).
+            Special values : if return == 0, srcData is not compressible => Nothing is stored within dst !!!
+                             if return == 1, srcData is a single byte symbol * srcSize times. Use RLE compression instead.
+                             if FSE_isError(return), compression failed (more details using FSE_getErrorName())
+        */
+        public static nuint FSE_compress(void* dst, nuint dstCapacity, void* src, nuint srcSize)
+        {
+            return FSE_compress2(dst, dstCapacity, src, srcSize, 255, (uint)((13 - 2)));
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/FseDecompress.cs

@@ -0,0 +1,446 @@
+using System;
+using System.Runtime.CompilerServices;
+using static ZstdSharp.UnsafeHelper;
+
+namespace ZstdSharp.Unsafe
+{
+    public static unsafe partial class Methods
+    {
+        /* Function templates */
+        public static uint* FSE_createDTable(uint tableLog)
+        {
+            if (tableLog > 15)
+            {
+                tableLog = 15;
+            }
+
+            return (uint*)(malloc((uint)((1 + (1 << (int)(tableLog)))) * (nuint)(sizeof(uint))));
+        }
+
+        public static void FSE_freeDTable(uint* dt)
+        {
+            free((void*)(dt));
+        }
+
+        private static nuint FSE_buildDTable_internal(uint* dt, short* normalizedCounter, uint maxSymbolValue, uint tableLog, void* workSpace, nuint wkspSize)
+        {
+            void* tdPtr = (void*)(dt + 1);
+            FSE_decode_t* tableDecode = (FSE_decode_t*)(tdPtr);
+            ushort* symbolNext = (ushort*)(workSpace);
+            byte* spread = (byte*)(symbolNext + maxSymbolValue + 1);
+            uint maxSV1 = maxSymbolValue + 1;
+            uint tableSize = (uint)(1 << (int)tableLog);
+            uint highThreshold = tableSize - 1;
+
+            if (((nuint)(sizeof(short)) * (maxSymbolValue + 1) + (1UL << (int)tableLog) + 8) > wkspSize)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_maxSymbolValue_tooLarge)));
+            }
+
+            if (maxSymbolValue > 255)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_maxSymbolValue_tooLarge)));
+            }
+
+            if (tableLog > (uint)((14 - 2)))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge)));
+            }
+
+
+            {
+                FSE_DTableHeader DTableH;
+
+                DTableH.tableLog = (ushort)(tableLog);
+                DTableH.fastMode = 1;
+
+                {
+                    short largeLimit = (short)(1 << (int)(tableLog - 1));
+                    uint s;
+
+                    for (s = 0; s < maxSV1; s++)
+                    {
+                        if (normalizedCounter[s] == -1)
+                        {
+                            tableDecode[highThreshold--].symbol = (byte)(s);
+                            symbolNext[s] = 1;
+                        }
+                        else
+                        {
+                            if (normalizedCounter[s] >= largeLimit)
+                            {
+                                DTableH.fastMode = 0;
+                            }
+
+                            symbolNext[s] = (ushort)(normalizedCounter[s]);
+                        }
+                    }
+                }
+
+                memcpy((void*)(dt), (void*)(&DTableH), ((nuint)(sizeof(FSE_DTableHeader))));
+            }
+
+            if (highThreshold == tableSize - 1)
+            {
+                nuint tableMask = tableSize - 1;
+                nuint step = (((tableSize) >> 1) + ((tableSize) >> 3) + 3);
+
+
+                {
+                    ulong add = 0x0101010101010101UL;
+                    nuint pos = 0;
+                    ulong sv = 0;
+                    uint s;
+
+                    for (s = 0; s < maxSV1; ++s , sv += add)
+                    {
+                        int i;
+                        int n = normalizedCounter[s];
+
+                        MEM_write64((void*)(spread + pos), sv);
+                        for (i = 8; i < n; i += 8)
+                        {
+                            MEM_write64((void*)(spread + pos + i), sv);
+                        }
+
+                        pos += (nuint)n;
+                    }
+                }
+
+
+                {
+                    nuint position = 0;
+                    nuint s;
+                    nuint unroll = 2;
+
+                    assert(tableSize % unroll == 0);
+                    for (s = 0; s < (nuint)(tableSize); s += unroll)
+                    {
+                        nuint u;
+
+                        for (u = 0; u < unroll; ++u)
+                        {
+                            nuint uPosition = (position + (u * step)) & tableMask;
+
+                            tableDecode[uPosition].symbol = spread[s + u];
+                        }
+
+                        position = (position + (unroll * step)) & tableMask;
+                    }
+
+                    assert(position == 0);
+                }
+            }
+            else
+            {
+                uint tableMask = tableSize - 1;
+                uint step = (((tableSize) >> 1) + ((tableSize) >> 3) + 3);
+                uint s, position = 0;
+
+                for (s = 0; s < maxSV1; s++)
+                {
+                    int i;
+
+                    for (i = 0; i < normalizedCounter[s]; i++)
+                    {
+                        tableDecode[position].symbol = (byte)(s);
+                        position = (position + step) & tableMask;
+                        while (position > highThreshold)
+                        {
+                            position = (position + step) & tableMask;
+                        }
+                    }
+                }
+
+                if (position != 0)
+                {
+                    return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+                }
+            }
+
+
+            {
+                uint u;
+
+                for (u = 0; u < tableSize; u++)
+                {
+                    byte symbol = (byte)(tableDecode[u].symbol);
+                    uint nextState = symbolNext[symbol]++;
+
+                    tableDecode[u].nbBits = (byte)(tableLog - BIT_highbit32(nextState));
+                    tableDecode[u].newState = (ushort)((nextState << (int)(tableDecode[u].nbBits)) - tableSize);
+                }
+            }
+
+            return 0;
+        }
+
+        public static nuint FSE_buildDTable_wksp(uint* dt, short* normalizedCounter, uint maxSymbolValue, uint tableLog, void* workSpace, nuint wkspSize)
+        {
+            return FSE_buildDTable_internal(dt, normalizedCounter, maxSymbolValue, tableLog, workSpace, wkspSize);
+        }
+
+        /*-*******************************************************
+        *  Decompression (Byte symbols)
+        *********************************************************/
+        public static nuint FSE_buildDTable_rle(uint* dt, byte symbolValue)
+        {
+            void* ptr = (void*)dt;
+            FSE_DTableHeader* DTableH = (FSE_DTableHeader*)(ptr);
+            void* dPtr = (void*)(dt + 1);
+            FSE_decode_t* cell = (FSE_decode_t*)(dPtr);
+
+            DTableH->tableLog = 0;
+            DTableH->fastMode = 0;
+            cell->newState = 0;
+            cell->symbol = symbolValue;
+            cell->nbBits = 0;
+            return 0;
+        }
+
+        public static nuint FSE_buildDTable_raw(uint* dt, uint nbBits)
+        {
+            void* ptr = (void*)dt;
+            FSE_DTableHeader* DTableH = (FSE_DTableHeader*)(ptr);
+            void* dPtr = (void*)(dt + 1);
+            FSE_decode_t* dinfo = (FSE_decode_t*)(dPtr);
+            uint tableSize = (uint)(1 << (int)nbBits);
+            uint tableMask = tableSize - 1;
+            uint maxSV1 = tableMask + 1;
+            uint s;
+
+            if (nbBits < 1)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            }
+
+            DTableH->tableLog = (ushort)(nbBits);
+            DTableH->fastMode = 1;
+            for (s = 0; s < maxSV1; s++)
+            {
+                dinfo[s].newState = 0;
+                dinfo[s].symbol = (byte)(s);
+                dinfo[s].nbBits = (byte)(nbBits);
+            }
+
+            return 0;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint FSE_decompress_usingDTable_generic(void* dst, nuint maxDstSize, void* cSrc, nuint cSrcSize, uint* dt, uint fast)
+        {
+            byte* ostart = (byte*)(dst);
+            byte* op = ostart;
+            byte* omax = op + maxDstSize;
+            byte* olimit = omax - 3;
+            BIT_DStream_t bitD;
+            FSE_DState_t state1;
+            FSE_DState_t state2;
+
+
+            {
+                nuint _var_err__ = BIT_initDStream(&bitD, cSrc, cSrcSize);
+
+                if ((ERR_isError(_var_err__)) != 0)
+                {
+                    return _var_err__;
+                }
+            }
+
+            FSE_initDState(&state1, &bitD, dt);
+            FSE_initDState(&state2, &bitD, dt);
+            for (; ((BIT_reloadDStream(&bitD) == BIT_DStream_status.BIT_DStream_unfinished) && (op < olimit)); op += 4)
+            {
+                op[0] = fast != 0 ? FSE_decodeSymbolFast(&state1, &bitD) : FSE_decodeSymbol(&state1, &bitD);
+                if ((uint)((14 - 2) * 2 + 7) > (nuint)(sizeof(nuint)) * 8)
+                {
+                    BIT_reloadDStream(&bitD);
+                }
+
+                op[1] = fast != 0 ? FSE_decodeSymbolFast(&state2, &bitD) : FSE_decodeSymbol(&state2, &bitD);
+                if ((uint)((14 - 2) * 4 + 7) > (nuint)(sizeof(nuint)) * 8)
+                {
+                    if (BIT_reloadDStream(&bitD) > BIT_DStream_status.BIT_DStream_unfinished)
+                    {
+                        op += 2;
+                        break;
+                    }
+                }
+
+                op[2] = fast != 0 ? FSE_decodeSymbolFast(&state1, &bitD) : FSE_decodeSymbol(&state1, &bitD);
+                if ((uint)((14 - 2) * 2 + 7) > (nuint)(sizeof(nuint)) * 8)
+                {
+                    BIT_reloadDStream(&bitD);
+                }
+
+                op[3] = fast != 0 ? FSE_decodeSymbolFast(&state2, &bitD) : FSE_decodeSymbol(&state2, &bitD);
+            }
+
+            while (1 != 0)
+            {
+                if (op > (omax - 2))
+                {
+                    return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall)));
+                }
+
+                *op++ = fast != 0 ? FSE_decodeSymbolFast(&state1, &bitD) : FSE_decodeSymbol(&state1, &bitD);
+                if (BIT_reloadDStream(&bitD) == BIT_DStream_status.BIT_DStream_overflow)
+                {
+                    *op++ = fast != 0 ? FSE_decodeSymbolFast(&state2, &bitD) : FSE_decodeSymbol(&state2, &bitD);
+                    break;
+                }
+
+                if (op > (omax - 2))
+                {
+                    return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall)));
+                }
+
+                *op++ = fast != 0 ? FSE_decodeSymbolFast(&state2, &bitD) : FSE_decodeSymbol(&state2, &bitD);
+                if (BIT_reloadDStream(&bitD) == BIT_DStream_status.BIT_DStream_overflow)
+                {
+                    *op++ = fast != 0 ? FSE_decodeSymbolFast(&state1, &bitD) : FSE_decodeSymbol(&state1, &bitD);
+                    break;
+                }
+            }
+
+            return (nuint)(op - ostart);
+        }
+
+        /*! FSE_decompress_usingDTable():
+            Decompress compressed source `cSrc` of size `cSrcSize` using `dt`
+            into `dst` which must be already allocated.
+            @return : size of regenerated data (necessarily <= `dstCapacity`),
+                      or an errorCode, which can be tested using FSE_isError() */
+        public static nuint FSE_decompress_usingDTable(void* dst, nuint originalSize, void* cSrc, nuint cSrcSize, uint* dt)
+        {
+            void* ptr = (void*)dt;
+            FSE_DTableHeader* DTableH = (FSE_DTableHeader*)(ptr);
+            uint fastMode = DTableH->fastMode;
+
+            if (fastMode != 0)
+            {
+                return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
+            }
+
+            return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
+        }
+
+        public static nuint FSE_decompress_wksp(void* dst, nuint dstCapacity, void* cSrc, nuint cSrcSize, uint maxLog, void* workSpace, nuint wkspSize)
+        {
+            return FSE_decompress_wksp_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 0);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static nuint FSE_decompress_wksp_body(void* dst, nuint dstCapacity, void* cSrc, nuint cSrcSize, uint maxLog, void* workSpace, nuint wkspSize, int bmi2)
+        {
+            byte* istart = (byte*)(cSrc);
+            byte* ip = istart;
+            uint tableLog;
+            uint maxSymbolValue = 255;
+            FSE_DecompressWksp* wksp = (FSE_DecompressWksp*)(workSpace);
+
+            if (wkspSize < (nuint)(sizeof(FSE_DecompressWksp)))
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_GENERIC)));
+            }
+
+
+            {
+                nuint NCountLength = FSE_readNCount_bmi2((short*)wksp->ncount, &maxSymbolValue, &tableLog, (void*)istart, cSrcSize, bmi2);
+
+                if ((ERR_isError(NCountLength)) != 0)
+                {
+                    return NCountLength;
+                }
+
+                if (tableLog > maxLog)
+                {
+                    return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge)));
+                }
+
+                assert(NCountLength <= cSrcSize);
+                ip += NCountLength;
+                cSrcSize -= NCountLength;
+            }
+
+            if ((((uint)((1 + (1 << (int)(tableLog)))) + ((((nuint)(sizeof(short)) * (maxSymbolValue + 1) + (1UL << (int)tableLog) + 8) + (nuint)(sizeof(uint)) - 1) / (nuint)(sizeof(uint))) + (uint)((255 + 1) / 2) + 1) * (nuint)(sizeof(uint))) > wkspSize)
+            {
+                return (unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_tableLog_tooLarge)));
+            }
+
+            workSpace = wksp->dtable + (1 + (1 << (int)(tableLog)));
+            wkspSize -= (nuint)(sizeof(FSE_DecompressWksp)) + ((uint)((1 + (1 << (int)(tableLog)))) * (nuint)(sizeof(uint)));
+
+            {
+                nuint _var_err__ = FSE_buildDTable_internal((uint*)wksp->dtable, (short*)wksp->ncount, maxSymbolValue, tableLog, workSpace, wkspSize);
+
+                if ((ERR_isError(_var_err__)) != 0)
+                {
+                    return _var_err__;
+                }
+            }
+
+
+            {
+                void* ptr = (void*)wksp->dtable;
+                FSE_DTableHeader* DTableH = (FSE_DTableHeader*)(ptr);
+                uint fastMode = DTableH->fastMode;
+
+                if (fastMode != 0)
+                {
+                    return FSE_decompress_usingDTable_generic(dst, dstCapacity, (void*)ip, cSrcSize, (uint*)wksp->dtable, 1);
+                }
+
+                return FSE_decompress_usingDTable_generic(dst, dstCapacity, (void*)ip, cSrcSize, (uint*)wksp->dtable, 0);
+            }
+        }
+
+        /* Avoids the FORCE_INLINE of the _body() function. */
+        private static nuint FSE_decompress_wksp_body_default(void* dst, nuint dstCapacity, void* cSrc, nuint cSrcSize, uint maxLog, void* workSpace, nuint wkspSize)
+        {
+            return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 0);
+        }
+
+        private static nuint FSE_decompress_wksp_body_bmi2(void* dst, nuint dstCapacity, void* cSrc, nuint cSrcSize, uint maxLog, void* workSpace, nuint wkspSize)
+        {
+            return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 1);
+        }
+
+        public static nuint FSE_decompress_wksp_bmi2(void* dst, nuint dstCapacity, void* cSrc, nuint cSrcSize, uint maxLog, void* workSpace, nuint wkspSize, int bmi2)
+        {
+            if (bmi2 != 0)
+            {
+                return FSE_decompress_wksp_body_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
+            }
+
+            return FSE_decompress_wksp_body_default(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
+        }
+
+        /*! FSE_buildDTable():
+            Builds 'dt', which must be already allocated, using FSE_createDTable().
+            return : 0, or an errorCode, which can be tested using FSE_isError() */
+        public static nuint FSE_buildDTable(uint* dt, short* normalizedCounter, uint maxSymbolValue, uint tableLog)
+        {
+            uint* wksp = stackalloc uint[8322];
+
+            return FSE_buildDTable_wksp(dt, normalizedCounter, maxSymbolValue, tableLog, (void*)wksp, (nuint)(sizeof(uint) * 8322));
+        }
+
+        /*! FSE_decompress():
+            Decompress FSE data from buffer 'cSrc', of size 'cSrcSize',
+            into already allocated destination buffer 'dst', of size 'dstCapacity'.
+            @return : size of regenerated data (<= maxDstSize),
+                      or an error code, which can be tested using FSE_isError() .
+
+            ** Important ** : FSE_decompress() does not decompress non-compressible nor RLE data !!!
+            Why ? : making this distinction requires a header.
+            Header management is intentionally delegated to the user layer, which can better manage special cases.
+        */
+        public static nuint FSE_decompress(void* dst, nuint dstCapacity, void* cSrc, nuint cSrcSize)
+        {
+            uint* wksp = stackalloc uint[5380];
+
+            return FSE_decompress_wksp(dst, dstCapacity, cSrc, cSrcSize, (uint)((14 - 2)), (void*)wksp, (nuint)(sizeof(uint) * 5380));
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HIST_checkInput_e.cs

@@ -0,0 +1,10 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    public enum HIST_checkInput_e
+    {
+        trustInput,
+        checkMaxSymbolValue,
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HUF_CElt_s.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /* static allocation of HUF's Compression Table */
+    /* this is a private definition, just exposed for allocation and strict aliasing purpose. never EVER access its members directly */
+    public partial struct HUF_CElt_s
+    {
+        public ushort val;
+
+        public byte nbBits;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HUF_CompressWeightsWksp.cs

@@ -0,0 +1,15 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    public unsafe partial struct HUF_CompressWeightsWksp
+    {
+        public fixed uint CTable[59];
+
+        public fixed uint scratchBuffer[30];
+
+        public fixed uint count[13];
+
+        public fixed short norm[13];
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HUF_DEltX1.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /*-***************************/
+    /*  single-symbol decoding   */
+    /*-***************************/
+    public partial struct HUF_DEltX1
+    {
+        /* single-symbol decoding */
+        public byte @byte;
+
+        /* single-symbol decoding */
+        public byte nbBits;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HUF_DEltX2.cs

@@ -0,0 +1,19 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    /* *************************/
+    /* double-symbols decoding */
+    /* *************************/
+    public partial struct HUF_DEltX2
+    {
+        /* double-symbols decoding */
+        public ushort sequence;
+
+        /* double-symbols decoding */
+        public byte nbBits;
+
+        /* double-symbols decoding */
+        public byte length;
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HUF_ReadDTableX1_Workspace.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    public unsafe partial struct HUF_ReadDTableX1_Workspace
+    {
+        public fixed uint rankVal[16];
+
+        public fixed uint rankStart[16];
+
+        public fixed uint statsWksp[218];
+
+        public fixed byte symbols[256];
+
+        public fixed byte huffWeight[256];
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HUF_ReadDTableX2_Workspace.cs

@@ -0,0 +1,389 @@
+using InlineIL;
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using static InlineIL.IL.Emit;
+
+namespace ZstdSharp.Unsafe
+{
+    public unsafe partial struct HUF_ReadDTableX2_Workspace
+    {
+        public _rankVal_e__FixedBuffer rankVal;
+
+        public fixed uint rankStats[13];
+
+        public fixed uint rankStart0[14];
+
+        public _sortedSymbol_e__FixedBuffer sortedSymbol;
+
+        public fixed byte weightList[256];
+
+        public fixed uint calleeWksp[218];
+
+        public unsafe partial struct _rankVal_e__FixedBuffer
+        {
+            public rankValCol_t e0;
+            public rankValCol_t e1;
+            public rankValCol_t e2;
+            public rankValCol_t e3;
+            public rankValCol_t e4;
+            public rankValCol_t e5;
+            public rankValCol_t e6;
+            public rankValCol_t e7;
+            public rankValCol_t e8;
+            public rankValCol_t e9;
+            public rankValCol_t e10;
+            public rankValCol_t e11;
+
+            public ref rankValCol_t this[int index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            public ref rankValCol_t this[uint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + index);
+            }
+
+            public ref rankValCol_t this[nuint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static implicit operator rankValCol_t*(in _rankVal_e__FixedBuffer t)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_rankVal_e__FixedBuffer), nameof(e0)));
+                return IL.ReturnPointer<rankValCol_t>();
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static rankValCol_t* operator +(in _rankVal_e__FixedBuffer t, uint index)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_rankVal_e__FixedBuffer), nameof(e0)));
+                Ldarg_1();
+                Conv_I();
+                Sizeof<rankValCol_t>();
+                Conv_I();
+                Mul();
+                Add();
+                return IL.ReturnPointer<rankValCol_t>();
+            }
+        }
+
+        public unsafe partial struct _sortedSymbol_e__FixedBuffer
+        {
+            public sortedSymbol_t e0;
+            public sortedSymbol_t e1;
+            public sortedSymbol_t e2;
+            public sortedSymbol_t e3;
+            public sortedSymbol_t e4;
+            public sortedSymbol_t e5;
+            public sortedSymbol_t e6;
+            public sortedSymbol_t e7;
+            public sortedSymbol_t e8;
+            public sortedSymbol_t e9;
+            public sortedSymbol_t e10;
+            public sortedSymbol_t e11;
+            public sortedSymbol_t e12;
+            public sortedSymbol_t e13;
+            public sortedSymbol_t e14;
+            public sortedSymbol_t e15;
+            public sortedSymbol_t e16;
+            public sortedSymbol_t e17;
+            public sortedSymbol_t e18;
+            public sortedSymbol_t e19;
+            public sortedSymbol_t e20;
+            public sortedSymbol_t e21;
+            public sortedSymbol_t e22;
+            public sortedSymbol_t e23;
+            public sortedSymbol_t e24;
+            public sortedSymbol_t e25;
+            public sortedSymbol_t e26;
+            public sortedSymbol_t e27;
+            public sortedSymbol_t e28;
+            public sortedSymbol_t e29;
+            public sortedSymbol_t e30;
+            public sortedSymbol_t e31;
+            public sortedSymbol_t e32;
+            public sortedSymbol_t e33;
+            public sortedSymbol_t e34;
+            public sortedSymbol_t e35;
+            public sortedSymbol_t e36;
+            public sortedSymbol_t e37;
+            public sortedSymbol_t e38;
+            public sortedSymbol_t e39;
+            public sortedSymbol_t e40;
+            public sortedSymbol_t e41;
+            public sortedSymbol_t e42;
+            public sortedSymbol_t e43;
+            public sortedSymbol_t e44;
+            public sortedSymbol_t e45;
+            public sortedSymbol_t e46;
+            public sortedSymbol_t e47;
+            public sortedSymbol_t e48;
+            public sortedSymbol_t e49;
+            public sortedSymbol_t e50;
+            public sortedSymbol_t e51;
+            public sortedSymbol_t e52;
+            public sortedSymbol_t e53;
+            public sortedSymbol_t e54;
+            public sortedSymbol_t e55;
+            public sortedSymbol_t e56;
+            public sortedSymbol_t e57;
+            public sortedSymbol_t e58;
+            public sortedSymbol_t e59;
+            public sortedSymbol_t e60;
+            public sortedSymbol_t e61;
+            public sortedSymbol_t e62;
+            public sortedSymbol_t e63;
+            public sortedSymbol_t e64;
+            public sortedSymbol_t e65;
+            public sortedSymbol_t e66;
+            public sortedSymbol_t e67;
+            public sortedSymbol_t e68;
+            public sortedSymbol_t e69;
+            public sortedSymbol_t e70;
+            public sortedSymbol_t e71;
+            public sortedSymbol_t e72;
+            public sortedSymbol_t e73;
+            public sortedSymbol_t e74;
+            public sortedSymbol_t e75;
+            public sortedSymbol_t e76;
+            public sortedSymbol_t e77;
+            public sortedSymbol_t e78;
+            public sortedSymbol_t e79;
+            public sortedSymbol_t e80;
+            public sortedSymbol_t e81;
+            public sortedSymbol_t e82;
+            public sortedSymbol_t e83;
+            public sortedSymbol_t e84;
+            public sortedSymbol_t e85;
+            public sortedSymbol_t e86;
+            public sortedSymbol_t e87;
+            public sortedSymbol_t e88;
+            public sortedSymbol_t e89;
+            public sortedSymbol_t e90;
+            public sortedSymbol_t e91;
+            public sortedSymbol_t e92;
+            public sortedSymbol_t e93;
+            public sortedSymbol_t e94;
+            public sortedSymbol_t e95;
+            public sortedSymbol_t e96;
+            public sortedSymbol_t e97;
+            public sortedSymbol_t e98;
+            public sortedSymbol_t e99;
+            public sortedSymbol_t e100;
+            public sortedSymbol_t e101;
+            public sortedSymbol_t e102;
+            public sortedSymbol_t e103;
+            public sortedSymbol_t e104;
+            public sortedSymbol_t e105;
+            public sortedSymbol_t e106;
+            public sortedSymbol_t e107;
+            public sortedSymbol_t e108;
+            public sortedSymbol_t e109;
+            public sortedSymbol_t e110;
+            public sortedSymbol_t e111;
+            public sortedSymbol_t e112;
+            public sortedSymbol_t e113;
+            public sortedSymbol_t e114;
+            public sortedSymbol_t e115;
+            public sortedSymbol_t e116;
+            public sortedSymbol_t e117;
+            public sortedSymbol_t e118;
+            public sortedSymbol_t e119;
+            public sortedSymbol_t e120;
+            public sortedSymbol_t e121;
+            public sortedSymbol_t e122;
+            public sortedSymbol_t e123;
+            public sortedSymbol_t e124;
+            public sortedSymbol_t e125;
+            public sortedSymbol_t e126;
+            public sortedSymbol_t e127;
+            public sortedSymbol_t e128;
+            public sortedSymbol_t e129;
+            public sortedSymbol_t e130;
+            public sortedSymbol_t e131;
+            public sortedSymbol_t e132;
+            public sortedSymbol_t e133;
+            public sortedSymbol_t e134;
+            public sortedSymbol_t e135;
+            public sortedSymbol_t e136;
+            public sortedSymbol_t e137;
+            public sortedSymbol_t e138;
+            public sortedSymbol_t e139;
+            public sortedSymbol_t e140;
+            public sortedSymbol_t e141;
+            public sortedSymbol_t e142;
+            public sortedSymbol_t e143;
+            public sortedSymbol_t e144;
+            public sortedSymbol_t e145;
+            public sortedSymbol_t e146;
+            public sortedSymbol_t e147;
+            public sortedSymbol_t e148;
+            public sortedSymbol_t e149;
+            public sortedSymbol_t e150;
+            public sortedSymbol_t e151;
+            public sortedSymbol_t e152;
+            public sortedSymbol_t e153;
+            public sortedSymbol_t e154;
+            public sortedSymbol_t e155;
+            public sortedSymbol_t e156;
+            public sortedSymbol_t e157;
+            public sortedSymbol_t e158;
+            public sortedSymbol_t e159;
+            public sortedSymbol_t e160;
+            public sortedSymbol_t e161;
+            public sortedSymbol_t e162;
+            public sortedSymbol_t e163;
+            public sortedSymbol_t e164;
+            public sortedSymbol_t e165;
+            public sortedSymbol_t e166;
+            public sortedSymbol_t e167;
+            public sortedSymbol_t e168;
+            public sortedSymbol_t e169;
+            public sortedSymbol_t e170;
+            public sortedSymbol_t e171;
+            public sortedSymbol_t e172;
+            public sortedSymbol_t e173;
+            public sortedSymbol_t e174;
+            public sortedSymbol_t e175;
+            public sortedSymbol_t e176;
+            public sortedSymbol_t e177;
+            public sortedSymbol_t e178;
+            public sortedSymbol_t e179;
+            public sortedSymbol_t e180;
+            public sortedSymbol_t e181;
+            public sortedSymbol_t e182;
+            public sortedSymbol_t e183;
+            public sortedSymbol_t e184;
+            public sortedSymbol_t e185;
+            public sortedSymbol_t e186;
+            public sortedSymbol_t e187;
+            public sortedSymbol_t e188;
+            public sortedSymbol_t e189;
+            public sortedSymbol_t e190;
+            public sortedSymbol_t e191;
+            public sortedSymbol_t e192;
+            public sortedSymbol_t e193;
+            public sortedSymbol_t e194;
+            public sortedSymbol_t e195;
+            public sortedSymbol_t e196;
+            public sortedSymbol_t e197;
+            public sortedSymbol_t e198;
+            public sortedSymbol_t e199;
+            public sortedSymbol_t e200;
+            public sortedSymbol_t e201;
+            public sortedSymbol_t e202;
+            public sortedSymbol_t e203;
+            public sortedSymbol_t e204;
+            public sortedSymbol_t e205;
+            public sortedSymbol_t e206;
+            public sortedSymbol_t e207;
+            public sortedSymbol_t e208;
+            public sortedSymbol_t e209;
+            public sortedSymbol_t e210;
+            public sortedSymbol_t e211;
+            public sortedSymbol_t e212;
+            public sortedSymbol_t e213;
+            public sortedSymbol_t e214;
+            public sortedSymbol_t e215;
+            public sortedSymbol_t e216;
+            public sortedSymbol_t e217;
+            public sortedSymbol_t e218;
+            public sortedSymbol_t e219;
+            public sortedSymbol_t e220;
+            public sortedSymbol_t e221;
+            public sortedSymbol_t e222;
+            public sortedSymbol_t e223;
+            public sortedSymbol_t e224;
+            public sortedSymbol_t e225;
+            public sortedSymbol_t e226;
+            public sortedSymbol_t e227;
+            public sortedSymbol_t e228;
+            public sortedSymbol_t e229;
+            public sortedSymbol_t e230;
+            public sortedSymbol_t e231;
+            public sortedSymbol_t e232;
+            public sortedSymbol_t e233;
+            public sortedSymbol_t e234;
+            public sortedSymbol_t e235;
+            public sortedSymbol_t e236;
+            public sortedSymbol_t e237;
+            public sortedSymbol_t e238;
+            public sortedSymbol_t e239;
+            public sortedSymbol_t e240;
+            public sortedSymbol_t e241;
+            public sortedSymbol_t e242;
+            public sortedSymbol_t e243;
+            public sortedSymbol_t e244;
+            public sortedSymbol_t e245;
+            public sortedSymbol_t e246;
+            public sortedSymbol_t e247;
+            public sortedSymbol_t e248;
+            public sortedSymbol_t e249;
+            public sortedSymbol_t e250;
+            public sortedSymbol_t e251;
+            public sortedSymbol_t e252;
+            public sortedSymbol_t e253;
+            public sortedSymbol_t e254;
+            public sortedSymbol_t e255;
+
+            public ref sortedSymbol_t this[int index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            public ref sortedSymbol_t this[uint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + index);
+            }
+
+            public ref sortedSymbol_t this[nuint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static implicit operator sortedSymbol_t*(in _sortedSymbol_e__FixedBuffer t)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_sortedSymbol_e__FixedBuffer), nameof(e0)));
+                return IL.ReturnPointer<sortedSymbol_t>();
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static sortedSymbol_t* operator +(in _sortedSymbol_e__FixedBuffer t, uint index)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_sortedSymbol_e__FixedBuffer), nameof(e0)));
+                Ldarg_1();
+                Conv_I();
+                Sizeof<sortedSymbol_t>();
+                Conv_I();
+                Mul();
+                Add();
+                return IL.ReturnPointer<sortedSymbol_t>();
+            }
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HUF_WriteCTableWksp.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace ZstdSharp.Unsafe
+{
+    public unsafe partial struct HUF_WriteCTableWksp
+    {
+        public HUF_CompressWeightsWksp wksp;
+
+        /* precomputed conversion table */
+        public fixed byte bitsToWeight[13];
+
+        public fixed byte huffWeight[255];
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HUF_buildCTable_wksp_tables.cs

@@ -0,0 +1,657 @@
+using InlineIL;
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using static InlineIL.IL.Emit;
+
+namespace ZstdSharp.Unsafe
+{
+    public partial struct HUF_buildCTable_wksp_tables
+    {
+        public _huffNodeTbl_e__FixedBuffer huffNodeTbl;
+
+        public _rankPosition_e__FixedBuffer rankPosition;
+
+        public unsafe partial struct _huffNodeTbl_e__FixedBuffer
+        {
+            public nodeElt_s e0;
+            public nodeElt_s e1;
+            public nodeElt_s e2;
+            public nodeElt_s e3;
+            public nodeElt_s e4;
+            public nodeElt_s e5;
+            public nodeElt_s e6;
+            public nodeElt_s e7;
+            public nodeElt_s e8;
+            public nodeElt_s e9;
+            public nodeElt_s e10;
+            public nodeElt_s e11;
+            public nodeElt_s e12;
+            public nodeElt_s e13;
+            public nodeElt_s e14;
+            public nodeElt_s e15;
+            public nodeElt_s e16;
+            public nodeElt_s e17;
+            public nodeElt_s e18;
+            public nodeElt_s e19;
+            public nodeElt_s e20;
+            public nodeElt_s e21;
+            public nodeElt_s e22;
+            public nodeElt_s e23;
+            public nodeElt_s e24;
+            public nodeElt_s e25;
+            public nodeElt_s e26;
+            public nodeElt_s e27;
+            public nodeElt_s e28;
+            public nodeElt_s e29;
+            public nodeElt_s e30;
+            public nodeElt_s e31;
+            public nodeElt_s e32;
+            public nodeElt_s e33;
+            public nodeElt_s e34;
+            public nodeElt_s e35;
+            public nodeElt_s e36;
+            public nodeElt_s e37;
+            public nodeElt_s e38;
+            public nodeElt_s e39;
+            public nodeElt_s e40;
+            public nodeElt_s e41;
+            public nodeElt_s e42;
+            public nodeElt_s e43;
+            public nodeElt_s e44;
+            public nodeElt_s e45;
+            public nodeElt_s e46;
+            public nodeElt_s e47;
+            public nodeElt_s e48;
+            public nodeElt_s e49;
+            public nodeElt_s e50;
+            public nodeElt_s e51;
+            public nodeElt_s e52;
+            public nodeElt_s e53;
+            public nodeElt_s e54;
+            public nodeElt_s e55;
+            public nodeElt_s e56;
+            public nodeElt_s e57;
+            public nodeElt_s e58;
+            public nodeElt_s e59;
+            public nodeElt_s e60;
+            public nodeElt_s e61;
+            public nodeElt_s e62;
+            public nodeElt_s e63;
+            public nodeElt_s e64;
+            public nodeElt_s e65;
+            public nodeElt_s e66;
+            public nodeElt_s e67;
+            public nodeElt_s e68;
+            public nodeElt_s e69;
+            public nodeElt_s e70;
+            public nodeElt_s e71;
+            public nodeElt_s e72;
+            public nodeElt_s e73;
+            public nodeElt_s e74;
+            public nodeElt_s e75;
+            public nodeElt_s e76;
+            public nodeElt_s e77;
+            public nodeElt_s e78;
+            public nodeElt_s e79;
+            public nodeElt_s e80;
+            public nodeElt_s e81;
+            public nodeElt_s e82;
+            public nodeElt_s e83;
+            public nodeElt_s e84;
+            public nodeElt_s e85;
+            public nodeElt_s e86;
+            public nodeElt_s e87;
+            public nodeElt_s e88;
+            public nodeElt_s e89;
+            public nodeElt_s e90;
+            public nodeElt_s e91;
+            public nodeElt_s e92;
+            public nodeElt_s e93;
+            public nodeElt_s e94;
+            public nodeElt_s e95;
+            public nodeElt_s e96;
+            public nodeElt_s e97;
+            public nodeElt_s e98;
+            public nodeElt_s e99;
+            public nodeElt_s e100;
+            public nodeElt_s e101;
+            public nodeElt_s e102;
+            public nodeElt_s e103;
+            public nodeElt_s e104;
+            public nodeElt_s e105;
+            public nodeElt_s e106;
+            public nodeElt_s e107;
+            public nodeElt_s e108;
+            public nodeElt_s e109;
+            public nodeElt_s e110;
+            public nodeElt_s e111;
+            public nodeElt_s e112;
+            public nodeElt_s e113;
+            public nodeElt_s e114;
+            public nodeElt_s e115;
+            public nodeElt_s e116;
+            public nodeElt_s e117;
+            public nodeElt_s e118;
+            public nodeElt_s e119;
+            public nodeElt_s e120;
+            public nodeElt_s e121;
+            public nodeElt_s e122;
+            public nodeElt_s e123;
+            public nodeElt_s e124;
+            public nodeElt_s e125;
+            public nodeElt_s e126;
+            public nodeElt_s e127;
+            public nodeElt_s e128;
+            public nodeElt_s e129;
+            public nodeElt_s e130;
+            public nodeElt_s e131;
+            public nodeElt_s e132;
+            public nodeElt_s e133;
+            public nodeElt_s e134;
+            public nodeElt_s e135;
+            public nodeElt_s e136;
+            public nodeElt_s e137;
+            public nodeElt_s e138;
+            public nodeElt_s e139;
+            public nodeElt_s e140;
+            public nodeElt_s e141;
+            public nodeElt_s e142;
+            public nodeElt_s e143;
+            public nodeElt_s e144;
+            public nodeElt_s e145;
+            public nodeElt_s e146;
+            public nodeElt_s e147;
+            public nodeElt_s e148;
+            public nodeElt_s e149;
+            public nodeElt_s e150;
+            public nodeElt_s e151;
+            public nodeElt_s e152;
+            public nodeElt_s e153;
+            public nodeElt_s e154;
+            public nodeElt_s e155;
+            public nodeElt_s e156;
+            public nodeElt_s e157;
+            public nodeElt_s e158;
+            public nodeElt_s e159;
+            public nodeElt_s e160;
+            public nodeElt_s e161;
+            public nodeElt_s e162;
+            public nodeElt_s e163;
+            public nodeElt_s e164;
+            public nodeElt_s e165;
+            public nodeElt_s e166;
+            public nodeElt_s e167;
+            public nodeElt_s e168;
+            public nodeElt_s e169;
+            public nodeElt_s e170;
+            public nodeElt_s e171;
+            public nodeElt_s e172;
+            public nodeElt_s e173;
+            public nodeElt_s e174;
+            public nodeElt_s e175;
+            public nodeElt_s e176;
+            public nodeElt_s e177;
+            public nodeElt_s e178;
+            public nodeElt_s e179;
+            public nodeElt_s e180;
+            public nodeElt_s e181;
+            public nodeElt_s e182;
+            public nodeElt_s e183;
+            public nodeElt_s e184;
+            public nodeElt_s e185;
+            public nodeElt_s e186;
+            public nodeElt_s e187;
+            public nodeElt_s e188;
+            public nodeElt_s e189;
+            public nodeElt_s e190;
+            public nodeElt_s e191;
+            public nodeElt_s e192;
+            public nodeElt_s e193;
+            public nodeElt_s e194;
+            public nodeElt_s e195;
+            public nodeElt_s e196;
+            public nodeElt_s e197;
+            public nodeElt_s e198;
+            public nodeElt_s e199;
+            public nodeElt_s e200;
+            public nodeElt_s e201;
+            public nodeElt_s e202;
+            public nodeElt_s e203;
+            public nodeElt_s e204;
+            public nodeElt_s e205;
+            public nodeElt_s e206;
+            public nodeElt_s e207;
+            public nodeElt_s e208;
+            public nodeElt_s e209;
+            public nodeElt_s e210;
+            public nodeElt_s e211;
+            public nodeElt_s e212;
+            public nodeElt_s e213;
+            public nodeElt_s e214;
+            public nodeElt_s e215;
+            public nodeElt_s e216;
+            public nodeElt_s e217;
+            public nodeElt_s e218;
+            public nodeElt_s e219;
+            public nodeElt_s e220;
+            public nodeElt_s e221;
+            public nodeElt_s e222;
+            public nodeElt_s e223;
+            public nodeElt_s e224;
+            public nodeElt_s e225;
+            public nodeElt_s e226;
+            public nodeElt_s e227;
+            public nodeElt_s e228;
+            public nodeElt_s e229;
+            public nodeElt_s e230;
+            public nodeElt_s e231;
+            public nodeElt_s e232;
+            public nodeElt_s e233;
+            public nodeElt_s e234;
+            public nodeElt_s e235;
+            public nodeElt_s e236;
+            public nodeElt_s e237;
+            public nodeElt_s e238;
+            public nodeElt_s e239;
+            public nodeElt_s e240;
+            public nodeElt_s e241;
+            public nodeElt_s e242;
+            public nodeElt_s e243;
+            public nodeElt_s e244;
+            public nodeElt_s e245;
+            public nodeElt_s e246;
+            public nodeElt_s e247;
+            public nodeElt_s e248;
+            public nodeElt_s e249;
+            public nodeElt_s e250;
+            public nodeElt_s e251;
+            public nodeElt_s e252;
+            public nodeElt_s e253;
+            public nodeElt_s e254;
+            public nodeElt_s e255;
+            public nodeElt_s e256;
+            public nodeElt_s e257;
+            public nodeElt_s e258;
+            public nodeElt_s e259;
+            public nodeElt_s e260;
+            public nodeElt_s e261;
+            public nodeElt_s e262;
+            public nodeElt_s e263;
+            public nodeElt_s e264;
+            public nodeElt_s e265;
+            public nodeElt_s e266;
+            public nodeElt_s e267;
+            public nodeElt_s e268;
+            public nodeElt_s e269;
+            public nodeElt_s e270;
+            public nodeElt_s e271;
+            public nodeElt_s e272;
+            public nodeElt_s e273;
+            public nodeElt_s e274;
+            public nodeElt_s e275;
+            public nodeElt_s e276;
+            public nodeElt_s e277;
+            public nodeElt_s e278;
+            public nodeElt_s e279;
+            public nodeElt_s e280;
+            public nodeElt_s e281;
+            public nodeElt_s e282;
+            public nodeElt_s e283;
+            public nodeElt_s e284;
+            public nodeElt_s e285;
+            public nodeElt_s e286;
+            public nodeElt_s e287;
+            public nodeElt_s e288;
+            public nodeElt_s e289;
+            public nodeElt_s e290;
+            public nodeElt_s e291;
+            public nodeElt_s e292;
+            public nodeElt_s e293;
+            public nodeElt_s e294;
+            public nodeElt_s e295;
+            public nodeElt_s e296;
+            public nodeElt_s e297;
+            public nodeElt_s e298;
+            public nodeElt_s e299;
+            public nodeElt_s e300;
+            public nodeElt_s e301;
+            public nodeElt_s e302;
+            public nodeElt_s e303;
+            public nodeElt_s e304;
+            public nodeElt_s e305;
+            public nodeElt_s e306;
+            public nodeElt_s e307;
+            public nodeElt_s e308;
+            public nodeElt_s e309;
+            public nodeElt_s e310;
+            public nodeElt_s e311;
+            public nodeElt_s e312;
+            public nodeElt_s e313;
+            public nodeElt_s e314;
+            public nodeElt_s e315;
+            public nodeElt_s e316;
+            public nodeElt_s e317;
+            public nodeElt_s e318;
+            public nodeElt_s e319;
+            public nodeElt_s e320;
+            public nodeElt_s e321;
+            public nodeElt_s e322;
+            public nodeElt_s e323;
+            public nodeElt_s e324;
+            public nodeElt_s e325;
+            public nodeElt_s e326;
+            public nodeElt_s e327;
+            public nodeElt_s e328;
+            public nodeElt_s e329;
+            public nodeElt_s e330;
+            public nodeElt_s e331;
+            public nodeElt_s e332;
+            public nodeElt_s e333;
+            public nodeElt_s e334;
+            public nodeElt_s e335;
+            public nodeElt_s e336;
+            public nodeElt_s e337;
+            public nodeElt_s e338;
+            public nodeElt_s e339;
+            public nodeElt_s e340;
+            public nodeElt_s e341;
+            public nodeElt_s e342;
+            public nodeElt_s e343;
+            public nodeElt_s e344;
+            public nodeElt_s e345;
+            public nodeElt_s e346;
+            public nodeElt_s e347;
+            public nodeElt_s e348;
+            public nodeElt_s e349;
+            public nodeElt_s e350;
+            public nodeElt_s e351;
+            public nodeElt_s e352;
+            public nodeElt_s e353;
+            public nodeElt_s e354;
+            public nodeElt_s e355;
+            public nodeElt_s e356;
+            public nodeElt_s e357;
+            public nodeElt_s e358;
+            public nodeElt_s e359;
+            public nodeElt_s e360;
+            public nodeElt_s e361;
+            public nodeElt_s e362;
+            public nodeElt_s e363;
+            public nodeElt_s e364;
+            public nodeElt_s e365;
+            public nodeElt_s e366;
+            public nodeElt_s e367;
+            public nodeElt_s e368;
+            public nodeElt_s e369;
+            public nodeElt_s e370;
+            public nodeElt_s e371;
+            public nodeElt_s e372;
+            public nodeElt_s e373;
+            public nodeElt_s e374;
+            public nodeElt_s e375;
+            public nodeElt_s e376;
+            public nodeElt_s e377;
+            public nodeElt_s e378;
+            public nodeElt_s e379;
+            public nodeElt_s e380;
+            public nodeElt_s e381;
+            public nodeElt_s e382;
+            public nodeElt_s e383;
+            public nodeElt_s e384;
+            public nodeElt_s e385;
+            public nodeElt_s e386;
+            public nodeElt_s e387;
+            public nodeElt_s e388;
+            public nodeElt_s e389;
+            public nodeElt_s e390;
+            public nodeElt_s e391;
+            public nodeElt_s e392;
+            public nodeElt_s e393;
+            public nodeElt_s e394;
+            public nodeElt_s e395;
+            public nodeElt_s e396;
+            public nodeElt_s e397;
+            public nodeElt_s e398;
+            public nodeElt_s e399;
+            public nodeElt_s e400;
+            public nodeElt_s e401;
+            public nodeElt_s e402;
+            public nodeElt_s e403;
+            public nodeElt_s e404;
+            public nodeElt_s e405;
+            public nodeElt_s e406;
+            public nodeElt_s e407;
+            public nodeElt_s e408;
+            public nodeElt_s e409;
+            public nodeElt_s e410;
+            public nodeElt_s e411;
+            public nodeElt_s e412;
+            public nodeElt_s e413;
+            public nodeElt_s e414;
+            public nodeElt_s e415;
+            public nodeElt_s e416;
+            public nodeElt_s e417;
+            public nodeElt_s e418;
+            public nodeElt_s e419;
+            public nodeElt_s e420;
+            public nodeElt_s e421;
+            public nodeElt_s e422;
+            public nodeElt_s e423;
+            public nodeElt_s e424;
+            public nodeElt_s e425;
+            public nodeElt_s e426;
+            public nodeElt_s e427;
+            public nodeElt_s e428;
+            public nodeElt_s e429;
+            public nodeElt_s e430;
+            public nodeElt_s e431;
+            public nodeElt_s e432;
+            public nodeElt_s e433;
+            public nodeElt_s e434;
+            public nodeElt_s e435;
+            public nodeElt_s e436;
+            public nodeElt_s e437;
+            public nodeElt_s e438;
+            public nodeElt_s e439;
+            public nodeElt_s e440;
+            public nodeElt_s e441;
+            public nodeElt_s e442;
+            public nodeElt_s e443;
+            public nodeElt_s e444;
+            public nodeElt_s e445;
+            public nodeElt_s e446;
+            public nodeElt_s e447;
+            public nodeElt_s e448;
+            public nodeElt_s e449;
+            public nodeElt_s e450;
+            public nodeElt_s e451;
+            public nodeElt_s e452;
+            public nodeElt_s e453;
+            public nodeElt_s e454;
+            public nodeElt_s e455;
+            public nodeElt_s e456;
+            public nodeElt_s e457;
+            public nodeElt_s e458;
+            public nodeElt_s e459;
+            public nodeElt_s e460;
+            public nodeElt_s e461;
+            public nodeElt_s e462;
+            public nodeElt_s e463;
+            public nodeElt_s e464;
+            public nodeElt_s e465;
+            public nodeElt_s e466;
+            public nodeElt_s e467;
+            public nodeElt_s e468;
+            public nodeElt_s e469;
+            public nodeElt_s e470;
+            public nodeElt_s e471;
+            public nodeElt_s e472;
+            public nodeElt_s e473;
+            public nodeElt_s e474;
+            public nodeElt_s e475;
+            public nodeElt_s e476;
+            public nodeElt_s e477;
+            public nodeElt_s e478;
+            public nodeElt_s e479;
+            public nodeElt_s e480;
+            public nodeElt_s e481;
+            public nodeElt_s e482;
+            public nodeElt_s e483;
+            public nodeElt_s e484;
+            public nodeElt_s e485;
+            public nodeElt_s e486;
+            public nodeElt_s e487;
+            public nodeElt_s e488;
+            public nodeElt_s e489;
+            public nodeElt_s e490;
+            public nodeElt_s e491;
+            public nodeElt_s e492;
+            public nodeElt_s e493;
+            public nodeElt_s e494;
+            public nodeElt_s e495;
+            public nodeElt_s e496;
+            public nodeElt_s e497;
+            public nodeElt_s e498;
+            public nodeElt_s e499;
+            public nodeElt_s e500;
+            public nodeElt_s e501;
+            public nodeElt_s e502;
+            public nodeElt_s e503;
+            public nodeElt_s e504;
+            public nodeElt_s e505;
+            public nodeElt_s e506;
+            public nodeElt_s e507;
+            public nodeElt_s e508;
+            public nodeElt_s e509;
+            public nodeElt_s e510;
+            public nodeElt_s e511;
+
+            public ref nodeElt_s this[int index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            public ref nodeElt_s this[uint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + index);
+            }
+
+            public ref nodeElt_s this[nuint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static implicit operator nodeElt_s*(in _huffNodeTbl_e__FixedBuffer t)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_huffNodeTbl_e__FixedBuffer), nameof(e0)));
+                return IL.ReturnPointer<nodeElt_s>();
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static nodeElt_s* operator +(in _huffNodeTbl_e__FixedBuffer t, uint index)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_huffNodeTbl_e__FixedBuffer), nameof(e0)));
+                Ldarg_1();
+                Conv_I();
+                Sizeof<nodeElt_s>();
+                Conv_I();
+                Mul();
+                Add();
+                return IL.ReturnPointer<nodeElt_s>();
+            }
+        }
+
+        public unsafe partial struct _rankPosition_e__FixedBuffer
+        {
+            public rankPos e0;
+            public rankPos e1;
+            public rankPos e2;
+            public rankPos e3;
+            public rankPos e4;
+            public rankPos e5;
+            public rankPos e6;
+            public rankPos e7;
+            public rankPos e8;
+            public rankPos e9;
+            public rankPos e10;
+            public rankPos e11;
+            public rankPos e12;
+            public rankPos e13;
+            public rankPos e14;
+            public rankPos e15;
+            public rankPos e16;
+            public rankPos e17;
+            public rankPos e18;
+            public rankPos e19;
+            public rankPos e20;
+            public rankPos e21;
+            public rankPos e22;
+            public rankPos e23;
+            public rankPos e24;
+            public rankPos e25;
+            public rankPos e26;
+            public rankPos e27;
+            public rankPos e28;
+            public rankPos e29;
+            public rankPos e30;
+            public rankPos e31;
+
+            public ref rankPos this[int index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            public ref rankPos this[uint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + index);
+            }
+
+            public ref rankPos this[nuint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static implicit operator rankPos*(in _rankPosition_e__FixedBuffer t)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_rankPosition_e__FixedBuffer), nameof(e0)));
+                return IL.ReturnPointer<rankPos>();
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static rankPos* operator +(in _rankPosition_e__FixedBuffer t, uint index)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_rankPosition_e__FixedBuffer), nameof(e0)));
+                Ldarg_1();
+                Conv_I();
+                Sizeof<rankPos>();
+                Conv_I();
+                Mul();
+                Add();
+                return IL.ReturnPointer<rankPos>();
+            }
+        }
+    }
+}

src/SharpCompress/Compressors/Zstd/Unsafe/HUF_compress_tables_t.cs

@@ -0,0 +1,322 @@
+using InlineIL;
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using static InlineIL.IL.Emit;
+
+namespace ZstdSharp.Unsafe
+{
+    public unsafe partial struct HUF_compress_tables_t
+    {
+        public fixed uint count[256];
+
+        public _CTable_e__FixedBuffer CTable;
+
+        public _wksps_e__Union wksps;
+
+        public unsafe partial struct _CTable_e__FixedBuffer
+        {
+            public HUF_CElt_s e0;
+            public HUF_CElt_s e1;
+            public HUF_CElt_s e2;
+            public HUF_CElt_s e3;
+            public HUF_CElt_s e4;
+            public HUF_CElt_s e5;
+            public HUF_CElt_s e6;
+            public HUF_CElt_s e7;
+            public HUF_CElt_s e8;
+            public HUF_CElt_s e9;
+            public HUF_CElt_s e10;
+            public HUF_CElt_s e11;
+            public HUF_CElt_s e12;
+            public HUF_CElt_s e13;
+            public HUF_CElt_s e14;
+            public HUF_CElt_s e15;
+            public HUF_CElt_s e16;
+            public HUF_CElt_s e17;
+            public HUF_CElt_s e18;
+            public HUF_CElt_s e19;
+            public HUF_CElt_s e20;
+            public HUF_CElt_s e21;
+            public HUF_CElt_s e22;
+            public HUF_CElt_s e23;
+            public HUF_CElt_s e24;
+            public HUF_CElt_s e25;
+            public HUF_CElt_s e26;
+            public HUF_CElt_s e27;
+            public HUF_CElt_s e28;
+            public HUF_CElt_s e29;
+            public HUF_CElt_s e30;
+            public HUF_CElt_s e31;
+            public HUF_CElt_s e32;
+            public HUF_CElt_s e33;
+            public HUF_CElt_s e34;
+            public HUF_CElt_s e35;
+            public HUF_CElt_s e36;
+            public HUF_CElt_s e37;
+            public HUF_CElt_s e38;
+            public HUF_CElt_s e39;
+            public HUF_CElt_s e40;
+            public HUF_CElt_s e41;
+            public HUF_CElt_s e42;
+            public HUF_CElt_s e43;
+            public HUF_CElt_s e44;
+            public HUF_CElt_s e45;
+            public HUF_CElt_s e46;
+            public HUF_CElt_s e47;
+            public HUF_CElt_s e48;
+            public HUF_CElt_s e49;
+            public HUF_CElt_s e50;
+            public HUF_CElt_s e51;
+            public HUF_CElt_s e52;
+            public HUF_CElt_s e53;
+            public HUF_CElt_s e54;
+            public HUF_CElt_s e55;
+            public HUF_CElt_s e56;
+            public HUF_CElt_s e57;
+            public HUF_CElt_s e58;
+            public HUF_CElt_s e59;
+            public HUF_CElt_s e60;
+            public HUF_CElt_s e61;
+            public HUF_CElt_s e62;
+            public HUF_CElt_s e63;
+            public HUF_CElt_s e64;
+            public HUF_CElt_s e65;
+            public HUF_CElt_s e66;
+            public HUF_CElt_s e67;
+            public HUF_CElt_s e68;
+            public HUF_CElt_s e69;
+            public HUF_CElt_s e70;
+            public HUF_CElt_s e71;
+            public HUF_CElt_s e72;
+            public HUF_CElt_s e73;
+            public HUF_CElt_s e74;
+            public HUF_CElt_s e75;
+            public HUF_CElt_s e76;
+            public HUF_CElt_s e77;
+            public HUF_CElt_s e78;
+            public HUF_CElt_s e79;
+            public HUF_CElt_s e80;
+            public HUF_CElt_s e81;
+            public HUF_CElt_s e82;
+            public HUF_CElt_s e83;
+            public HUF_CElt_s e84;
+            public HUF_CElt_s e85;
+            public HUF_CElt_s e86;
+            public HUF_CElt_s e87;
+            public HUF_CElt_s e88;
+            public HUF_CElt_s e89;
+            public HUF_CElt_s e90;
+            public HUF_CElt_s e91;
+            public HUF_CElt_s e92;
+            public HUF_CElt_s e93;
+            public HUF_CElt_s e94;
+            public HUF_CElt_s e95;
+            public HUF_CElt_s e96;
+            public HUF_CElt_s e97;
+            public HUF_CElt_s e98;
+            public HUF_CElt_s e99;
+            public HUF_CElt_s e100;
+            public HUF_CElt_s e101;
+            public HUF_CElt_s e102;
+            public HUF_CElt_s e103;
+            public HUF_CElt_s e104;
+            public HUF_CElt_s e105;
+            public HUF_CElt_s e106;
+            public HUF_CElt_s e107;
+            public HUF_CElt_s e108;
+            public HUF_CElt_s e109;
+            public HUF_CElt_s e110;
+            public HUF_CElt_s e111;
+            public HUF_CElt_s e112;
+            public HUF_CElt_s e113;
+            public HUF_CElt_s e114;
+            public HUF_CElt_s e115;
+            public HUF_CElt_s e116;
+            public HUF_CElt_s e117;
+            public HUF_CElt_s e118;
+            public HUF_CElt_s e119;
+            public HUF_CElt_s e120;
+            public HUF_CElt_s e121;
+            public HUF_CElt_s e122;
+            public HUF_CElt_s e123;
+            public HUF_CElt_s e124;
+            public HUF_CElt_s e125;
+            public HUF_CElt_s e126;
+            public HUF_CElt_s e127;
+            public HUF_CElt_s e128;
+            public HUF_CElt_s e129;
+            public HUF_CElt_s e130;
+            public HUF_CElt_s e131;
+            public HUF_CElt_s e132;
+            public HUF_CElt_s e133;
+            public HUF_CElt_s e134;
+            public HUF_CElt_s e135;
+            public HUF_CElt_s e136;
+            public HUF_CElt_s e137;
+            public HUF_CElt_s e138;
+            public HUF_CElt_s e139;
+            public HUF_CElt_s e140;
+            public HUF_CElt_s e141;
+            public HUF_CElt_s e142;
+            public HUF_CElt_s e143;
+            public HUF_CElt_s e144;
+            public HUF_CElt_s e145;
+            public HUF_CElt_s e146;
+            public HUF_CElt_s e147;
+            public HUF_CElt_s e148;
+            public HUF_CElt_s e149;
+            public HUF_CElt_s e150;
+            public HUF_CElt_s e151;
+            public HUF_CElt_s e152;
+            public HUF_CElt_s e153;
+            public HUF_CElt_s e154;
+            public HUF_CElt_s e155;
+            public HUF_CElt_s e156;
+            public HUF_CElt_s e157;
+            public HUF_CElt_s e158;
+            public HUF_CElt_s e159;
+            public HUF_CElt_s e160;
+            public HUF_CElt_s e161;
+            public HUF_CElt_s e162;
+            public HUF_CElt_s e163;
+            public HUF_CElt_s e164;
+            public HUF_CElt_s e165;
+            public HUF_CElt_s e166;
+            public HUF_CElt_s e167;
+            public HUF_CElt_s e168;
+            public HUF_CElt_s e169;
+            public HUF_CElt_s e170;
+            public HUF_CElt_s e171;
+            public HUF_CElt_s e172;
+            public HUF_CElt_s e173;
+            public HUF_CElt_s e174;
+            public HUF_CElt_s e175;
+            public HUF_CElt_s e176;
+            public HUF_CElt_s e177;
+            public HUF_CElt_s e178;
+            public HUF_CElt_s e179;
+            public HUF_CElt_s e180;
+            public HUF_CElt_s e181;
+            public HUF_CElt_s e182;
+            public HUF_CElt_s e183;
+            public HUF_CElt_s e184;
+            public HUF_CElt_s e185;
+            public HUF_CElt_s e186;
+            public HUF_CElt_s e187;
+            public HUF_CElt_s e188;
+            public HUF_CElt_s e189;
+            public HUF_CElt_s e190;
+            public HUF_CElt_s e191;
+            public HUF_CElt_s e192;
+            public HUF_CElt_s e193;
+            public HUF_CElt_s e194;
+            public HUF_CElt_s e195;
+            public HUF_CElt_s e196;
+            public HUF_CElt_s e197;
+            public HUF_CElt_s e198;
+            public HUF_CElt_s e199;
+            public HUF_CElt_s e200;
+            public HUF_CElt_s e201;
+            public HUF_CElt_s e202;
+            public HUF_CElt_s e203;
+            public HUF_CElt_s e204;
+            public HUF_CElt_s e205;
+            public HUF_CElt_s e206;
+            public HUF_CElt_s e207;
+            public HUF_CElt_s e208;
+            public HUF_CElt_s e209;
+            public HUF_CElt_s e210;
+            public HUF_CElt_s e211;
+            public HUF_CElt_s e212;
+            public HUF_CElt_s e213;
+            public HUF_CElt_s e214;
+            public HUF_CElt_s e215;
+            public HUF_CElt_s e216;
+            public HUF_CElt_s e217;
+            public HUF_CElt_s e218;
+            public HUF_CElt_s e219;
+            public HUF_CElt_s e220;
+            public HUF_CElt_s e221;
+            public HUF_CElt_s e222;
+            public HUF_CElt_s e223;
+            public HUF_CElt_s e224;
+            public HUF_CElt_s e225;
+            public HUF_CElt_s e226;
+            public HUF_CElt_s e227;
+            public HUF_CElt_s e228;
+            public HUF_CElt_s e229;
+            public HUF_CElt_s e230;
+            public HUF_CElt_s e231;
+            public HUF_CElt_s e232;
+            public HUF_CElt_s e233;
+            public HUF_CElt_s e234;
+            public HUF_CElt_s e235;
+            public HUF_CElt_s e236;
+            public HUF_CElt_s e237;
+            public HUF_CElt_s e238;
+            public HUF_CElt_s e239;
+            public HUF_CElt_s e240;
+            public HUF_CElt_s e241;
+            public HUF_CElt_s e242;
+            public HUF_CElt_s e243;
+            public HUF_CElt_s e244;
+            public HUF_CElt_s e245;
+            public HUF_CElt_s e246;
+            public HUF_CElt_s e247;
+            public HUF_CElt_s e248;
+            public HUF_CElt_s e249;
+            public HUF_CElt_s e250;
+            public HUF_CElt_s e251;
+            public HUF_CElt_s e252;
+            public HUF_CElt_s e253;
+            public HUF_CElt_s e254;
+            public HUF_CElt_s e255;
+
+            public ref HUF_CElt_s this[int index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            public ref HUF_CElt_s this[uint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + index);
+            }
+
+            public ref HUF_CElt_s this[nuint index]
+            {
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                [InlineMethod.Inline]
+                get => ref *(this + (uint)index);
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static implicit operator HUF_CElt_s*(in _CTable_e__FixedBuffer t)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_CTable_e__FixedBuffer), nameof(e0)));
+                return IL.ReturnPointer<HUF_CElt_s>();
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            [InlineMethod.Inline]
+            public static HUF_CElt_s* operator +(in _CTable_e__FixedBuffer t, uint index)
+            {
+                Ldarg_0();
+                Ldflda(new FieldRef(typeof(_CTable_e__FixedBuffer), nameof(e0)));
+                Ldarg_1();
+                Conv_I();
+                Sizeof<HUF_CElt_s>();
+                Conv_I();
+                Mul();
+                Add();
+                return IL.ReturnPointer<HUF_CElt_s>();
+            }
+        }
+    }
+}