Merge branch 'master' into adam/zstd

.copilot-agent.yml

@@ -1,7 +0,0 @@
-enabled: true
-agent:
-  name: copilot-coding-agent
-  allow:
-    - paths: ["src/**/*", "tests/**/*", "README.md", "AGENTS.md"]
-      actions: ["create", "modify"]
-  require_review_before_merge: true

.github/COPILOT_AGENT_README.md

@@ -1,13 +0,0 @@
-# Copilot Coding Agent Configuration
-
-This repository includes a minimal opt-in configuration and CI workflow to allow the GitHub Copilot coding agent to open and validate PRs.
-
-- .copilot-agent.yml: opt-in config for automated agents
-- .github/workflows/dotnetcore.yml: CI runs on PRs touching the solution, source, or tests to validate changes
-- AGENTS.yml: general information for this project
-
-Maintainers can adjust the allowed paths or disable the agent by editing or removing .copilot-agent.yml.
-
-Notes:
-- Do not change any other files in the repository.
-- If build/test paths are different, update the workflow accordingly; this workflow targets SharpCompress.sln and the SharpCompress.Tests test project.

.github/agents/copilot-agent.yml

@@ -1,17 +0,0 @@
-enabled: true
-agent:
-  name: copilot-coding-agent
-  allow:
-    - paths: ["src/**/*", "tests/**/*", "README.md", "AGENTS.md"]
-      actions: ["create", "modify", "delete"]
-  require_review_before_merge: true
-  required_approvals: 1
-  allowed_merge_strategies:
-    - squash
-    - merge
-  auto_merge_on_green: false
-  run_workflows: true
-notes: |
-  - This manifest expresses the policy for the Copilot coding agent in this repository.
-  - It does NOT install or authorize the agent; a repository admin must install the Copilot coding agent app and grant the repository the necessary permissions (contents: write, pull_requests: write, checks: write, actions: write/read, issues: write) to allow the agent to act.
-  - Keep allow paths narrow and prefer require_review_before_merge during initial rollout.

.github/workflows/dotnetcore.yml

@@ -14,12 +14,12 @@ jobs:
         os: [windows-latest, ubuntu-latest]
 
     steps:
-    - uses: actions/checkout@v5
-    - uses: actions/setup-dotnet@v5
+    - uses: actions/checkout@v4
+    - uses: actions/setup-dotnet@v4
       with:
         dotnet-version: 8.0.x
     - run: dotnet run --project build/build.csproj
-    - uses: actions/upload-artifact@v5
+    - uses: actions/upload-artifact@v4
       with:
         name: ${{ matrix.os }}-sharpcompress.nupkg
         path: artifacts/*

AGENTS.md

@@ -26,7 +26,6 @@ applyTo: '**/*.cs'
 - Use CSharpier for all code formatting to ensure consistent style across the project.
 - Install CSharpier globally: `dotnet tool install -g csharpier`
 - Format files with: `dotnet csharpier format .`
-- **ALWAYS run `dotnet csharpier format .` after making code changes before committing.**
 - Configure your IDE to format on save using CSharpier.
 - CSharpier configuration can be customized via `.csharpierrc` file in the project root.
 - Trust CSharpier's opinionated formatting decisions to maintain consistency.

Directory.Packages.props

@@ -1,11 +1,10 @@
 <Project>
   <ItemGroup>
     <PackageVersion Include="Bullseye" Version="6.0.0" />
-    <PackageVersion Include="AwesomeAssertions" Version="9.2.1" />
+    <PackageVersion Include="AwesomeAssertions" Version="9.2.0" />
     <PackageVersion Include="Glob" Version="1.1.9" />
-    <PackageVersion Include="JetBrains.Profiler.SelfApi" Version="2.5.14" />
     <PackageVersion Include="Microsoft.Bcl.AsyncInterfaces" Version="8.0.0" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
     <PackageVersion Include="Mono.Posix.NETStandard" Version="1.0.0" />
     <PackageVersion Include="SimpleExec" Version="12.0.0" />
     <PackageVersion Include="System.Buffers" Version="4.6.1" />
@@ -13,6 +12,7 @@
     <PackageVersion Include="System.Text.Encoding.CodePages" Version="8.0.0" />
     <PackageVersion Include="xunit" Version="2.9.3" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
+    <PackageVersion Include="xunit.SkippableFact" Version="1.5.23" />
     <PackageVersion Include="ZstdSharp.Port" Version="0.8.6" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />

README.md

@@ -4,8 +4,6 @@ SharpCompress is a compression library in pure C# for .NET Framework 4.62, .NET
 
 The major feature is support for non-seekable streams so large files can be processed on the fly (i.e. download stream).
 
-**NEW:** All I/O operations now support async/await for improved performance and scalability. See the [Async Usage](#async-usage) section below.
-
 GitHub Actions Build -
 [![SharpCompress](https://github.com/adamhathcock/sharpcompress/actions/workflows/dotnetcore.yml/badge.svg)](https://github.com/adamhathcock/sharpcompress/actions/workflows/dotnetcore.yml)
 [![Static Badge](https://img.shields.io/badge/API%20Docs-DNDocs-190088?logo=readme&logoColor=white)](https://dndocs.com/d/sharpcompress/api/index.html)
@@ -34,82 +32,6 @@ Hi everyone. I hope you're using SharpCompress and finding it useful. Please giv
 
 Please do not email me directly to ask for help. If you think there is a real issue, please report it here.
 
-## Async Usage
-
-SharpCompress now provides full async/await support for all I/O operations, allowing for better performance and scalability in modern applications.
-
-### Async Reading Examples
-
-Extract entries asynchronously:
-```csharp
-using (Stream stream = File.OpenRead("archive.zip"))
-using (var reader = ReaderFactory.Open(stream))
-{
-    while (reader.MoveToNextEntry())
-    {
-        if (!reader.Entry.IsDirectory)
-        {
-            // Async extraction
-            await reader.WriteEntryToDirectoryAsync(
-                @"C:\temp",
-                new ExtractionOptions() { ExtractFullPath = true, Overwrite = true },
-                cancellationToken
-            );
-        }
-    }
-}
-```
-
-Extract all entries to directory asynchronously:
-```csharp
-using (Stream stream = File.OpenRead("archive.tar.gz"))
-using (var reader = ReaderFactory.Open(stream))
-{
-    await reader.WriteAllToDirectoryAsync(
-        @"C:\temp",
-        new ExtractionOptions() { ExtractFullPath = true, Overwrite = true },
-        cancellationToken
-    );
-}
-```
-
-Open entry stream asynchronously:
-```csharp
-using (var archive = ZipArchive.Open("archive.zip"))
-{
-    foreach (var entry in archive.Entries.Where(e => !e.IsDirectory))
-    {
-        using (var entryStream = await entry.OpenEntryStreamAsync(cancellationToken))
-        {
-            // Process stream asynchronously
-            await entryStream.CopyToAsync(outputStream, cancellationToken);
-        }
-    }
-}
-```
-
-### Async Writing Examples
-
-Write files asynchronously:
-```csharp
-using (Stream stream = File.OpenWrite("output.zip"))
-using (var writer = WriterFactory.Open(stream, ArchiveType.Zip, CompressionType.Deflate))
-{
-    await writer.WriteAsync("file1.txt", fileStream, DateTime.Now, cancellationToken);
-}
-```
-
-Write all files from directory asynchronously:
-```csharp
-using (Stream stream = File.OpenWrite("output.tar.gz"))
-using (var writer = WriterFactory.Open(stream, ArchiveType.Tar, new WriterOptions(CompressionType.GZip)))
-{
-    await writer.WriteAllAsync(@"D:\files", "*", SearchOption.AllDirectories, cancellationToken);
-}
-```
-
-All async methods support `CancellationToken` for graceful cancellation of long-running operations.
-
 ## Want to contribute?
 
 I'm always looking for help or ideas. Please submit code or email with ideas. Unfortunately, just letting me know you'd like to help is not enough because I really have no overall plan of what needs to be done. I'll definitely accept code submissions and add you as a member of the project!

SharpCompress.sln

@@ -21,14 +21,8 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Config", "Config", "{CDB425
 		Directory.Packages.props = Directory.Packages.props
 		NuGet.config = NuGet.config
 		.github\workflows\dotnetcore.yml = .github\workflows\dotnetcore.yml
-		USAGE.md = USAGE.md
-		README.md = README.md
-		FORMATS.md = FORMATS.md
-		AGENTS.md = AGENTS.md
 	EndProjectSection
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SharpCompress.Performance", "tests\SharpCompress.Performance\SharpCompress.Performance.csproj", "{5BDE6DBC-9E5F-4E21-AB71-F138A3E72B17}"
-EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -47,10 +41,6 @@ Global
 		{D4D613CB-5E94-47FB-85BE-B8423D20C545}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{D4D613CB-5E94-47FB-85BE-B8423D20C545}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{D4D613CB-5E94-47FB-85BE-B8423D20C545}.Release|Any CPU.Build.0 = Release|Any CPU
-		{5BDE6DBC-9E5F-4E21-AB71-F138A3E72B17}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{5BDE6DBC-9E5F-4E21-AB71-F138A3E72B17}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{5BDE6DBC-9E5F-4E21-AB71-F138A3E72B17}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{5BDE6DBC-9E5F-4E21-AB71-F138A3E72B17}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -58,6 +48,5 @@ Global
 	GlobalSection(NestedProjects) = preSolution
 		{FD19DDD8-72B2-4024-8665-0D1F7A2AA998} = {3C5BE746-03E5-4895-9988-0B57F162F86C}
 		{F2B1A1EB-0FA6-40D0-8908-E13247C7226F} = {0F0901FF-E8D9-426A-B5A2-17C7F47C1529}
-		{5BDE6DBC-9E5F-4E21-AB71-F138A3E72B17} = {0F0901FF-E8D9-426A-B5A2-17C7F47C1529}
 	EndGlobalSection
 EndGlobal

USAGE.md

@@ -1,18 +1,5 @@
 # SharpCompress Usage
 
-## Async/Await Support
-
-SharpCompress now provides full async/await support for all I/O operations. All `Read`, `Write`, and extraction operations have async equivalents ending in `Async` that accept an optional `CancellationToken`. This enables better performance and scalability for I/O-bound operations.
-
-**Key Async Methods:**
-- `reader.WriteEntryToAsync(stream, cancellationToken)` - Extract entry asynchronously  
-- `reader.WriteAllToDirectoryAsync(path, options, cancellationToken)` - Extract all asynchronously
-- `writer.WriteAsync(filename, stream, modTime, cancellationToken)` - Write entry asynchronously
-- `writer.WriteAllAsync(directory, pattern, searchOption, cancellationToken)` - Write directory asynchronously
-- `entry.OpenEntryStreamAsync(cancellationToken)` - Open entry stream asynchronously
-
-See [Async Examples](#async-examples) section below for usage patterns.
-
 ## Stream Rules (changed with 0.21)
 
 When dealing with Streams, the rule should be that you don't close a stream you didn't create. This, in effect, should mean you should always put a Stream in a using block to dispose it. 
@@ -185,133 +172,3 @@ foreach(var entry in tr.Entries)
     Console.WriteLine($"{entry.Key}");
 }
 ```
-
-## Async Examples
-
-### Async Reader Examples
-
-**Extract single entry asynchronously:**
-```C#
-using (Stream stream = File.OpenRead("archive.zip"))
-using (var reader = ReaderFactory.Open(stream))
-{
-    while (reader.MoveToNextEntry())
-    {
-        if (!reader.Entry.IsDirectory)
-        {
-            using (var entryStream = reader.OpenEntryStream())
-            {
-                using (var outputStream = File.Create("output.bin"))
-                {
-                    await reader.WriteEntryToAsync(outputStream, cancellationToken);
-                }
-            }
-        }
-    }
-}
-```
-
-**Extract all entries asynchronously:**
-```C#
-using (Stream stream = File.OpenRead("archive.tar.gz"))
-using (var reader = ReaderFactory.Open(stream))
-{
-    await reader.WriteAllToDirectoryAsync(
-        @"D:\temp",
-        new ExtractionOptions()
-        {
-            ExtractFullPath = true,
-            Overwrite = true
-        },
-        cancellationToken
-    );
-}
-```
-
-**Open and process entry stream asynchronously:**
-```C#
-using (var archive = ZipArchive.Open("archive.zip"))
-{
-    foreach (var entry in archive.Entries.Where(e => !e.IsDirectory))
-    {
-        using (var entryStream = await entry.OpenEntryStreamAsync(cancellationToken))
-        {
-            // Process the decompressed stream asynchronously
-            await ProcessStreamAsync(entryStream, cancellationToken);
-        }
-    }
-}
-```
-
-### Async Writer Examples
-
-**Write single file asynchronously:**
-```C#
-using (Stream archiveStream = File.OpenWrite("output.zip"))
-using (var writer = WriterFactory.Open(archiveStream, ArchiveType.Zip, CompressionType.Deflate))
-{
-    using (Stream fileStream = File.OpenRead("input.txt"))
-    {
-        await writer.WriteAsync("entry.txt", fileStream, DateTime.Now, cancellationToken);
-    }
-}
-```
-
-**Write entire directory asynchronously:**
-```C#
-using (Stream stream = File.OpenWrite("backup.tar.gz"))
-using (var writer = WriterFactory.Open(stream, ArchiveType.Tar, new WriterOptions(CompressionType.GZip)))
-{
-    await writer.WriteAllAsync(
-        @"D:\files",
-        "*",
-        SearchOption.AllDirectories,
-        cancellationToken
-    );
-}
-```
-
-**Write with progress tracking and cancellation:**
-```C#
-var cts = new CancellationTokenSource();
-
-// Set timeout or cancel from UI
-cts.CancelAfter(TimeSpan.FromMinutes(5));
-
-using (Stream stream = File.OpenWrite("archive.zip"))
-using (var writer = WriterFactory.Open(stream, ArchiveType.Zip, CompressionType.Deflate))
-{
-    try
-    {
-        await writer.WriteAllAsync(@"D:\data", "*", SearchOption.AllDirectories, cts.Token);
-    }
-    catch (OperationCanceledException)
-    {
-        Console.WriteLine("Operation was cancelled");
-    }
-}
-```
-
-### Archive Async Examples
-
-**Extract from archive asynchronously:**
-```C#
-using (var archive = ZipArchive.Open("archive.zip"))
-{
-    using (var reader = archive.ExtractAllEntries())
-    {
-        await reader.WriteAllToDirectoryAsync(
-            @"C:\output",
-            new ExtractionOptions() { ExtractFullPath = true, Overwrite = true },
-            cancellationToken
-        );
-    }
-}
-```
-
-**Benefits of Async Operations:**
-- Non-blocking I/O for better application responsiveness
-- Improved scalability for server applications
-- Support for cancellation via CancellationToken
-- Better resource utilization in async/await contexts
-- Compatible with modern .NET async patterns

src/SharpCompress/Archives/AbstractArchive.cs

@@ -144,12 +144,6 @@ public abstract class AbstractArchive<TEntry, TVolume> : IArchive, IArchiveExtra
     /// <returns></returns>
     public IReader ExtractAllEntries()
     {
-        if (!IsSolid && Type != ArchiveType.SevenZip)
-        {
-            throw new InvalidOperationException(
-                "ExtractAllEntries can only be used on solid archives or 7Zip archives (which require random access)."
-            );
-        }
         ((IArchiveExtractionListener)this).EnsureEntriesLoaded();
         return CreateReaderForSolidExtraction();
     }

src/SharpCompress/Archives/ArchiveFactory.cs

@@ -20,9 +20,8 @@ public static class ArchiveFactory
     public static IArchive Open(Stream stream, ReaderOptions? readerOptions = null)
     {
         readerOptions ??= new ReaderOptions();
-        var factory = FindFactory<IArchiveFactory>(stream);
         stream = new SharpCompressStream(stream, bufferSize: readerOptions.BufferSize);
-        return factory.Open(stream, readerOptions);
+        return FindFactory<IArchiveFactory>(stream).Open(stream, readerOptions);
     }
 
     public static IWritableArchive Create(ArchiveType type)
@@ -46,7 +45,7 @@ public static class ArchiveFactory
     /// <param name="options"></param>
     public static IArchive Open(string filePath, ReaderOptions? options = null)
     {
-        filePath.NotNullOrEmpty(nameof(filePath));
+        filePath.CheckNotNullOrEmpty(nameof(filePath));
         return Open(new FileInfo(filePath), options);
     }
 
@@ -69,7 +68,7 @@ public static class ArchiveFactory
     /// <param name="options"></param>
     public static IArchive Open(IEnumerable<FileInfo> fileInfos, ReaderOptions? options = null)
     {
-        fileInfos.NotNull(nameof(fileInfos));
+        fileInfos.CheckNotNull(nameof(fileInfos));
         var filesArray = fileInfos.ToArray();
         if (filesArray.Length == 0)
         {
@@ -82,7 +81,7 @@ public static class ArchiveFactory
             return Open(fileInfo, options);
         }
 
-        fileInfo.NotNull(nameof(fileInfo));
+        fileInfo.CheckNotNull(nameof(fileInfo));
         options ??= new ReaderOptions { LeaveStreamOpen = false };
 
         return FindFactory<IMultiArchiveFactory>(fileInfo).Open(filesArray, options);
@@ -95,7 +94,7 @@ public static class ArchiveFactory
     /// <param name="options"></param>
     public static IArchive Open(IEnumerable<Stream> streams, ReaderOptions? options = null)
     {
-        streams.NotNull(nameof(streams));
+        streams.CheckNotNull(nameof(streams));
         var streamsArray = streams.ToArray();
         if (streamsArray.Length == 0)
         {
@@ -108,7 +107,7 @@ public static class ArchiveFactory
             return Open(firstStream, options);
         }
 
-        firstStream.NotNull(nameof(firstStream));
+        firstStream.CheckNotNull(nameof(firstStream));
         options ??= new ReaderOptions();
 
         return FindFactory<IMultiArchiveFactory>(firstStream).Open(streamsArray, options);
@@ -130,7 +129,7 @@ public static class ArchiveFactory
     private static T FindFactory<T>(FileInfo finfo)
         where T : IFactory
     {
-        finfo.NotNull(nameof(finfo));
+        finfo.CheckNotNull(nameof(finfo));
         using Stream stream = finfo.OpenRead();
         return FindFactory<T>(stream);
     }
@@ -138,7 +137,7 @@ public static class ArchiveFactory
     private static T FindFactory<T>(Stream stream)
         where T : IFactory
     {
-        stream.NotNull(nameof(stream));
+        stream.CheckNotNull(nameof(stream));
         if (!stream.CanRead || !stream.CanSeek)
         {
             throw new ArgumentException("Stream should be readable and seekable");
@@ -173,7 +172,7 @@ public static class ArchiveFactory
         int bufferSize = ReaderOptions.DefaultBufferSize
     )
     {
-        filePath.NotNullOrEmpty(nameof(filePath));
+        filePath.CheckNotNullOrEmpty(nameof(filePath));
         using Stream s = File.OpenRead(filePath);
         return IsArchive(s, out type, bufferSize);
     }
@@ -185,7 +184,7 @@ public static class ArchiveFactory
     )
     {
         type = null;
-        stream.NotNull(nameof(stream));
+        stream.CheckNotNull(nameof(stream));
 
         if (!stream.CanRead || !stream.CanSeek)
         {
@@ -216,7 +215,7 @@ public static class ArchiveFactory
     /// <returns></returns>
     public static IEnumerable<string> GetFileParts(string part1)
     {
-        part1.NotNullOrEmpty(nameof(part1));
+        part1.CheckNotNullOrEmpty(nameof(part1));
         return GetFileParts(new FileInfo(part1)).Select(a => a.FullName);
     }
 
@@ -227,7 +226,7 @@ public static class ArchiveFactory
     /// <returns></returns>
     public static IEnumerable<FileInfo> GetFileParts(FileInfo part1)
     {
-        part1.NotNull(nameof(part1));
+        part1.CheckNotNull(nameof(part1));
         yield return part1;
 
         foreach (var factory in Factory.Factories.OfType<IFactory>())

src/SharpCompress/Archives/GZip/GZipArchive.cs

@@ -21,7 +21,7 @@ public class GZipArchive : AbstractWritableArchive<GZipArchiveEntry, GZipVolume>
     /// <param name="readerOptions"></param>
     public static GZipArchive Open(string filePath, ReaderOptions? readerOptions = null)
     {
-        filePath.NotNullOrEmpty(nameof(filePath));
+        filePath.CheckNotNullOrEmpty(nameof(filePath));
         return Open(new FileInfo(filePath), readerOptions ?? new ReaderOptions());
     }
 
@@ -32,7 +32,7 @@ public class GZipArchive : AbstractWritableArchive<GZipArchiveEntry, GZipVolume>
     /// <param name="readerOptions"></param>
     public static GZipArchive Open(FileInfo fileInfo, ReaderOptions? readerOptions = null)
     {
-        fileInfo.NotNull(nameof(fileInfo));
+        fileInfo.CheckNotNull(nameof(fileInfo));
         return new GZipArchive(
             new SourceStream(
                 fileInfo,
@@ -52,7 +52,7 @@ public class GZipArchive : AbstractWritableArchive<GZipArchiveEntry, GZipVolume>
         ReaderOptions? readerOptions = null
     )
     {
-        fileInfos.NotNull(nameof(fileInfos));
+        fileInfos.CheckNotNull(nameof(fileInfos));
         var files = fileInfos.ToArray();
         return new GZipArchive(
             new SourceStream(
@@ -70,7 +70,7 @@ public class GZipArchive : AbstractWritableArchive<GZipArchiveEntry, GZipVolume>
     /// <param name="readerOptions"></param>
     public static GZipArchive Open(IEnumerable<Stream> streams, ReaderOptions? readerOptions = null)
     {
-        streams.NotNull(nameof(streams));
+        streams.CheckNotNull(nameof(streams));
         var strms = streams.ToArray();
         return new GZipArchive(
             new SourceStream(
@@ -88,7 +88,7 @@ public class GZipArchive : AbstractWritableArchive<GZipArchiveEntry, GZipVolume>
     /// <param name="readerOptions"></param>
     public static GZipArchive Open(Stream stream, ReaderOptions? readerOptions = null)
     {
-        stream.NotNull(nameof(stream));
+        stream.CheckNotNull(nameof(stream));
 
         if (stream is not { CanSeek: true })
         {

src/SharpCompress/Archives/GZip/GZipArchiveEntry.cs

@@ -1,7 +1,5 @@
 using System.IO;
 using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common.GZip;
 
 namespace SharpCompress.Archives.GZip;
@@ -22,12 +20,6 @@ public class GZipArchiveEntry : GZipEntry, IArchiveEntry
         return Parts.Single().GetCompressedStream().NotNull();
     }
 
-    public virtual Task<Stream> OpenEntryStreamAsync(CancellationToken cancellationToken = default)
-    {
-        // GZip synchronous implementation is fast enough, just wrap it
-        return Task.FromResult(OpenEntryStream());
-    }
-
     #region IArchiveEntry Members
 
     public IArchive Archive { get; }

src/SharpCompress/Archives/IArchiveEntry.cs

@@ -1,6 +1,4 @@
 using System.IO;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common;
 
 namespace SharpCompress.Archives;
@@ -13,12 +11,6 @@ public interface IArchiveEntry : IEntry
     /// </summary>
     Stream OpenEntryStream();
 
-    /// <summary>
-    /// Opens the current entry as a stream that will decompress as it is read asynchronously.
-    /// Read the entire stream or use SkipEntry on EntryStream.
-    /// </summary>
-    Task<Stream> OpenEntryStreamAsync(CancellationToken cancellationToken = default);
-
     /// <summary>
     /// The archive can find all the parts of the archive needed to extract this entry.
     /// </summary>

src/SharpCompress/Archives/IArchiveEntryExtensions.cs

@@ -25,7 +25,7 @@ public static class IArchiveEntryExtensions
         using (entryStream)
         {
             using Stream s = new ListeningStream(streamListener, entryStream);
-            s.CopyTo(streamToWriteTo);
+            s.TransferTo(streamToWriteTo);
         }
         streamListener.FireEntryExtractionEnd(archiveEntry);
     }

src/SharpCompress/Archives/IArchiveExtensions.cs

@@ -45,10 +45,12 @@ public static class IArchiveExtensions
         var seenDirectories = new HashSet<string>();
 
         // Extract
-        foreach (var entry in archive.Entries)
+        var entries = archive.ExtractAllEntries();
+        while (entries.MoveToNextEntry())
         {
             cancellationToken.ThrowIfCancellationRequested();
 
+            var entry = entries.Entry;
             if (entry.IsDirectory)
             {
                 var dirPath = Path.Combine(destination, entry.Key.NotNull("Entry Key is null"));
@@ -75,7 +77,7 @@ public static class IArchiveExtensions
 
             // Write file
             using var fs = File.OpenWrite(path);
-            entry.WriteTo(fs);
+            entries.WriteEntryTo(fs);
 
             // Update progress
             bytesRead += entry.Size;

src/SharpCompress/Archives/Rar/RarArchive.cs

@@ -95,7 +95,7 @@ public class RarArchive : AbstractArchive<RarArchiveEntry, RarVolume>
     /// <param name="options"></param>
     public static RarArchive Open(string filePath, ReaderOptions? options = null)
     {
-        filePath.NotNullOrEmpty(nameof(filePath));
+        filePath.CheckNotNullOrEmpty(nameof(filePath));
         var fileInfo = new FileInfo(filePath);
         return new RarArchive(
             new SourceStream(
@@ -113,7 +113,7 @@ public class RarArchive : AbstractArchive<RarArchiveEntry, RarVolume>
     /// <param name="options"></param>
     public static RarArchive Open(FileInfo fileInfo, ReaderOptions? options = null)
     {
-        fileInfo.NotNull(nameof(fileInfo));
+        fileInfo.CheckNotNull(nameof(fileInfo));
         return new RarArchive(
             new SourceStream(
                 fileInfo,
@@ -130,7 +130,7 @@ public class RarArchive : AbstractArchive<RarArchiveEntry, RarVolume>
     /// <param name="options"></param>
     public static RarArchive Open(Stream stream, ReaderOptions? options = null)
     {
-        stream.NotNull(nameof(stream));
+        stream.CheckNotNull(nameof(stream));
 
         if (stream is not { CanSeek: true })
         {
@@ -150,7 +150,7 @@ public class RarArchive : AbstractArchive<RarArchiveEntry, RarVolume>
         ReaderOptions? readerOptions = null
     )
     {
-        fileInfos.NotNull(nameof(fileInfos));
+        fileInfos.CheckNotNull(nameof(fileInfos));
         var files = fileInfos.ToArray();
         return new RarArchive(
             new SourceStream(
@@ -168,7 +168,7 @@ public class RarArchive : AbstractArchive<RarArchiveEntry, RarVolume>
     /// <param name="readerOptions"></param>
     public static RarArchive Open(IEnumerable<Stream> streams, ReaderOptions? readerOptions = null)
     {
-        streams.NotNull(nameof(streams));
+        streams.CheckNotNull(nameof(streams));
         var strms = streams.ToArray();
         return new RarArchive(
             new SourceStream(

src/SharpCompress/Archives/Rar/RarArchiveEntry.cs

@@ -2,8 +2,6 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common;
 using SharpCompress.Common.Rar;
 using SharpCompress.Common.Rar.Headers;
@@ -86,9 +84,6 @@ public class RarArchiveEntry : RarEntry, IArchiveEntry
         );
     }
 
-    public Task<Stream> OpenEntryStreamAsync(CancellationToken cancellationToken = default) =>
-        Task.FromResult(OpenEntryStream());
-
     public bool IsComplete
     {
         get

src/SharpCompress/Archives/SevenZip/SevenZipArchive.cs

@@ -21,7 +21,7 @@ public class SevenZipArchive : AbstractArchive<SevenZipArchiveEntry, SevenZipVol
     /// <param name="readerOptions"></param>
     public static SevenZipArchive Open(string filePath, ReaderOptions? readerOptions = null)
     {
-        filePath.NotNullOrEmpty("filePath");
+        filePath.CheckNotNullOrEmpty("filePath");
         return Open(new FileInfo(filePath), readerOptions ?? new ReaderOptions());
     }
 
@@ -32,7 +32,7 @@ public class SevenZipArchive : AbstractArchive<SevenZipArchiveEntry, SevenZipVol
     /// <param name="readerOptions"></param>
     public static SevenZipArchive Open(FileInfo fileInfo, ReaderOptions? readerOptions = null)
     {
-        fileInfo.NotNull("fileInfo");
+        fileInfo.CheckNotNull("fileInfo");
         return new SevenZipArchive(
             new SourceStream(
                 fileInfo,
@@ -52,7 +52,7 @@ public class SevenZipArchive : AbstractArchive<SevenZipArchiveEntry, SevenZipVol
         ReaderOptions? readerOptions = null
     )
     {
-        fileInfos.NotNull(nameof(fileInfos));
+        fileInfos.CheckNotNull(nameof(fileInfos));
         var files = fileInfos.ToArray();
         return new SevenZipArchive(
             new SourceStream(
@@ -73,7 +73,7 @@ public class SevenZipArchive : AbstractArchive<SevenZipArchiveEntry, SevenZipVol
         ReaderOptions? readerOptions = null
     )
     {
-        streams.NotNull(nameof(streams));
+        streams.CheckNotNull(nameof(streams));
         var strms = streams.ToArray();
         return new SevenZipArchive(
             new SourceStream(
@@ -91,7 +91,7 @@ public class SevenZipArchive : AbstractArchive<SevenZipArchiveEntry, SevenZipVol
     /// <param name="readerOptions"></param>
     public static SevenZipArchive Open(Stream stream, ReaderOptions? readerOptions = null)
     {
-        stream.NotNull("stream");
+        stream.CheckNotNull("stream");
 
         if (stream is not { CanSeek: true })
         {

src/SharpCompress/Archives/SevenZip/SevenZipArchiveEntry.cs

@@ -1,6 +1,4 @@
 using System.IO;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common.SevenZip;
 
 namespace SharpCompress.Archives.SevenZip;
@@ -12,9 +10,6 @@ public class SevenZipArchiveEntry : SevenZipEntry, IArchiveEntry
 
     public Stream OpenEntryStream() => FilePart.GetCompressedStream();
 
-    public Task<Stream> OpenEntryStreamAsync(CancellationToken cancellationToken = default) =>
-        Task.FromResult(OpenEntryStream());
-
     public IArchive Archive { get; }
 
     public bool IsComplete => true;

src/SharpCompress/Archives/Tar/TarArchive.cs

@@ -22,7 +22,7 @@ public class TarArchive : AbstractWritableArchive<TarArchiveEntry, TarVolume>
     /// <param name="readerOptions"></param>
     public static TarArchive Open(string filePath, ReaderOptions? readerOptions = null)
     {
-        filePath.NotNullOrEmpty(nameof(filePath));
+        filePath.CheckNotNullOrEmpty(nameof(filePath));
         return Open(new FileInfo(filePath), readerOptions ?? new ReaderOptions());
     }
 
@@ -33,7 +33,7 @@ public class TarArchive : AbstractWritableArchive<TarArchiveEntry, TarVolume>
     /// <param name="readerOptions"></param>
     public static TarArchive Open(FileInfo fileInfo, ReaderOptions? readerOptions = null)
     {
-        fileInfo.NotNull(nameof(fileInfo));
+        fileInfo.CheckNotNull(nameof(fileInfo));
         return new TarArchive(
             new SourceStream(
                 fileInfo,
@@ -53,7 +53,7 @@ public class TarArchive : AbstractWritableArchive<TarArchiveEntry, TarVolume>
         ReaderOptions? readerOptions = null
     )
     {
-        fileInfos.NotNull(nameof(fileInfos));
+        fileInfos.CheckNotNull(nameof(fileInfos));
         var files = fileInfos.ToArray();
         return new TarArchive(
             new SourceStream(
@@ -71,7 +71,7 @@ public class TarArchive : AbstractWritableArchive<TarArchiveEntry, TarVolume>
     /// <param name="readerOptions"></param>
     public static TarArchive Open(IEnumerable<Stream> streams, ReaderOptions? readerOptions = null)
     {
-        streams.NotNull(nameof(streams));
+        streams.CheckNotNull(nameof(streams));
         var strms = streams.ToArray();
         return new TarArchive(
             new SourceStream(
@@ -89,7 +89,7 @@ public class TarArchive : AbstractWritableArchive<TarArchiveEntry, TarVolume>
     /// <param name="readerOptions"></param>
     public static TarArchive Open(Stream stream, ReaderOptions? readerOptions = null)
     {
-        stream.NotNull(nameof(stream));
+        stream.CheckNotNull(nameof(stream));
 
         if (stream is not { CanSeek: true })
         {
@@ -178,7 +178,7 @@ public class TarArchive : AbstractWritableArchive<TarArchiveEntry, TarVolume>
                         using (var entryStream = entry.OpenEntryStream())
                         {
                             using var memoryStream = new MemoryStream();
-                            entryStream.CopyTo(memoryStream);
+                            entryStream.TransferTo(memoryStream);
                             memoryStream.Position = 0;
                             var bytes = memoryStream.ToArray();
 

src/SharpCompress/Archives/Tar/TarArchiveEntry.cs

@@ -1,7 +1,5 @@
 using System.IO;
 using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common;
 using SharpCompress.Common.Tar;
 
@@ -14,10 +12,6 @@ public class TarArchiveEntry : TarEntry, IArchiveEntry
 
     public virtual Stream OpenEntryStream() => Parts.Single().GetCompressedStream().NotNull();
 
-    public virtual Task<Stream> OpenEntryStreamAsync(
-        CancellationToken cancellationToken = default
-    ) => Task.FromResult(OpenEntryStream());
-
     #region IArchiveEntry Members
 
     public IArchive Archive { get; }

src/SharpCompress/Archives/Zip/ZipArchive.cs

@@ -43,7 +43,7 @@ public class ZipArchive : AbstractWritableArchive<ZipArchiveEntry, ZipVolume>
     /// <param name="readerOptions"></param>
     public static ZipArchive Open(string filePath, ReaderOptions? readerOptions = null)
     {
-        filePath.NotNullOrEmpty(nameof(filePath));
+        filePath.CheckNotNullOrEmpty(nameof(filePath));
         return Open(new FileInfo(filePath), readerOptions ?? new ReaderOptions());
     }
 
@@ -54,7 +54,7 @@ public class ZipArchive : AbstractWritableArchive<ZipArchiveEntry, ZipVolume>
     /// <param name="readerOptions"></param>
     public static ZipArchive Open(FileInfo fileInfo, ReaderOptions? readerOptions = null)
     {
-        fileInfo.NotNull(nameof(fileInfo));
+        fileInfo.CheckNotNull(nameof(fileInfo));
         return new ZipArchive(
             new SourceStream(
                 fileInfo,
@@ -74,7 +74,7 @@ public class ZipArchive : AbstractWritableArchive<ZipArchiveEntry, ZipVolume>
         ReaderOptions? readerOptions = null
     )
     {
-        fileInfos.NotNull(nameof(fileInfos));
+        fileInfos.CheckNotNull(nameof(fileInfos));
         var files = fileInfos.ToArray();
         return new ZipArchive(
             new SourceStream(
@@ -92,7 +92,7 @@ public class ZipArchive : AbstractWritableArchive<ZipArchiveEntry, ZipVolume>
     /// <param name="readerOptions"></param>
     public static ZipArchive Open(IEnumerable<Stream> streams, ReaderOptions? readerOptions = null)
     {
-        streams.NotNull(nameof(streams));
+        streams.CheckNotNull(nameof(streams));
         var strms = streams.ToArray();
         return new ZipArchive(
             new SourceStream(
@@ -110,7 +110,7 @@ public class ZipArchive : AbstractWritableArchive<ZipArchiveEntry, ZipVolume>
     /// <param name="readerOptions"></param>
     public static ZipArchive Open(Stream stream, ReaderOptions? readerOptions = null)
     {
-        stream.NotNull(nameof(stream));
+        stream.CheckNotNull(nameof(stream));
 
         if (stream is not { CanSeek: true })
         {

src/SharpCompress/Archives/Zip/ZipArchiveEntry.cs

@@ -1,7 +1,5 @@
 using System.IO;
 using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common.Zip;
 
 namespace SharpCompress.Archives.Zip;
@@ -13,10 +11,6 @@ public class ZipArchiveEntry : ZipEntry, IArchiveEntry
 
     public virtual Stream OpenEntryStream() => Parts.Single().GetCompressedStream().NotNull();
 
-    public virtual Task<Stream> OpenEntryStreamAsync(
-        CancellationToken cancellationToken = default
-    ) => Task.FromResult(OpenEntryStream());
-
     #region IArchiveEntry Members
 
     public IArchive Archive { get; }

src/SharpCompress/AssemblyInfo.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Runtime.CompilerServices;
 
-[assembly: CLSCompliant(true)]
+[assembly: CLSCompliant(false)]
 [assembly: InternalsVisibleTo(
     "SharpCompress.Test,PublicKey=0024000004800000940000000602000000240000525341310004000001000100158bebf1433f76dffc356733c138babea7a47536c65ed8009b16372c6f4edbb20554db74a62687f56b97c20a6ce8c4b123280279e33c894e7b3aa93ab3c573656fde4db576cfe07dba09619ead26375b25d2c4a8e43f7be257d712b0dd2eb546f67adb09281338618a58ac834fc038dd7e2740a7ab3591826252e4f4516306dc"
 )]

src/SharpCompress/Common/Arc/ArcEntry.cs

@@ -7,54 +7,53 @@ using System.Threading.Tasks;
 using SharpCompress.Common.GZip;
 using SharpCompress.Common.Tar;
 
-namespace SharpCompress.Common.Arc
+namespace SharpCompress.Common.Arc;
+
+public class ArcEntry : Entry
 {
-    public class ArcEntry : Entry
+    private readonly ArcFilePart? _filePart;
+
+    internal ArcEntry(ArcFilePart? filePart)
     {
-        private readonly ArcFilePart? _filePart;
-
-        internal ArcEntry(ArcFilePart? filePart)
-        {
-            _filePart = filePart;
-        }
-
-        public override long Crc
-        {
-            get
-            {
-                if (_filePart == null)
-                {
-                    return 0;
-                }
-                return _filePart.Header.Crc16;
-            }
-        }
-
-        public override string? Key => _filePart?.Header.Name;
-
-        public override string? LinkTarget => null;
-
-        public override long CompressedSize => _filePart?.Header.CompressedSize ?? 0;
-
-        public override CompressionType CompressionType =>
-            _filePart?.Header.CompressionMethod ?? CompressionType.Unknown;
-
-        public override long Size => throw new NotImplementedException();
-
-        public override DateTime? LastModifiedTime => null;
-
-        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.Empty();
+        _filePart = filePart;
     }
+
+    public override long Crc
+    {
+        get
+        {
+            if (_filePart == null)
+            {
+                return 0;
+            }
+            return _filePart.Header.Crc16;
+        }
+    }
+
+    public override string? Key => _filePart?.Header.Name;
+
+    public override string? LinkTarget => null;
+
+    public override long CompressedSize => _filePart?.Header.CompressedSize ?? 0;
+
+    public override CompressionType CompressionType =>
+        _filePart?.Header.CompressionMethod ?? CompressionType.Unknown;
+
+    public override long Size => throw new NotImplementedException();
+
+    public override DateTime? LastModifiedTime => null;
+
+    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.Empty();
 }

src/SharpCompress/Common/Arc/ArcEntryHeader.cs

@@ -3,74 +3,73 @@ using System.IO;
 using System.Linq;
 using System.Text;
 
-namespace SharpCompress.Common.Arc
+namespace SharpCompress.Common.Arc;
+
+public class ArcEntryHeader
 {
-    public class ArcEntryHeader
+    public ArchiveEncoding ArchiveEncoding { get; }
+    public CompressionType CompressionMethod { get; private set; }
+    public string? Name { get; private set; }
+    public long CompressedSize { get; private set; }
+    public DateTime DateTime { get; private set; }
+    public int Crc16 { get; private set; }
+    public long OriginalSize { get; private set; }
+    public long DataStartPosition { get; private set; }
+
+    public ArcEntryHeader(ArchiveEncoding archiveEncoding)
     {
-        public ArchiveEncoding ArchiveEncoding { get; }
-        public CompressionType CompressionMethod { get; private set; }
-        public string? Name { get; private set; }
-        public long CompressedSize { get; private set; }
-        public DateTime DateTime { get; private set; }
-        public int Crc16 { get; private set; }
-        public long OriginalSize { get; private set; }
-        public long DataStartPosition { get; private set; }
+        this.ArchiveEncoding = archiveEncoding;
+    }
 
-        public ArcEntryHeader(ArchiveEncoding archiveEncoding)
+    public ArcEntryHeader? ReadHeader(Stream stream)
+    {
+        byte[] headerBytes = new byte[29];
+        if (stream.Read(headerBytes, 0, headerBytes.Length) != headerBytes.Length)
         {
-            this.ArchiveEncoding = archiveEncoding;
+            return null;
         }
+        DataStartPosition = stream.Position;
+        return LoadFrom(headerBytes);
+    }
 
-        public ArcEntryHeader? ReadHeader(Stream stream)
+    public ArcEntryHeader LoadFrom(byte[] headerBytes)
+    {
+        CompressionMethod = GetCompressionType(headerBytes[1]);
+
+        // Read name
+        int nameEnd = Array.IndexOf(headerBytes, (byte)0, 1); // Find null terminator
+        Name = Encoding.UTF8.GetString(headerBytes, 2, nameEnd > 0 ? nameEnd - 2 : 12);
+
+        int offset = 15;
+        CompressedSize = BitConverter.ToUInt32(headerBytes, offset);
+        offset += 4;
+        uint rawDateTime = BitConverter.ToUInt32(headerBytes, offset);
+        DateTime = ConvertToDateTime(rawDateTime);
+        offset += 4;
+        Crc16 = BitConverter.ToUInt16(headerBytes, offset);
+        offset += 2;
+        OriginalSize = BitConverter.ToUInt32(headerBytes, offset);
+        return this;
+    }
+
+    private CompressionType GetCompressionType(byte value)
+    {
+        return value switch
         {
-            byte[] headerBytes = new byte[29];
-            if (stream.Read(headerBytes, 0, headerBytes.Length) != headerBytes.Length)
-            {
-                return null;
-            }
-            DataStartPosition = stream.Position;
-            return LoadFrom(headerBytes);
-        }
+            1 or 2 => CompressionType.None,
+            3 => CompressionType.RLE90,
+            4 => CompressionType.Squeezed,
+            5 or 6 or 7 or 8 => CompressionType.Crunched,
+            9 => CompressionType.Squashed,
+            10 => CompressionType.Crushed,
+            11 => CompressionType.Distilled,
+            _ => CompressionType.Unknown,
+        };
+    }
 
-        public ArcEntryHeader LoadFrom(byte[] headerBytes)
-        {
-            CompressionMethod = GetCompressionType(headerBytes[1]);
-
-            // Read name
-            int nameEnd = Array.IndexOf(headerBytes, (byte)0, 1); // Find null terminator
-            Name = Encoding.UTF8.GetString(headerBytes, 2, nameEnd > 0 ? nameEnd - 2 : 12);
-
-            int offset = 15;
-            CompressedSize = BitConverter.ToUInt32(headerBytes, offset);
-            offset += 4;
-            uint rawDateTime = BitConverter.ToUInt32(headerBytes, offset);
-            DateTime = ConvertToDateTime(rawDateTime);
-            offset += 4;
-            Crc16 = BitConverter.ToUInt16(headerBytes, offset);
-            offset += 2;
-            OriginalSize = BitConverter.ToUInt32(headerBytes, offset);
-            return this;
-        }
-
-        private CompressionType GetCompressionType(byte value)
-        {
-            return value switch
-            {
-                1 or 2 => CompressionType.None,
-                3 => CompressionType.RLE90,
-                4 => CompressionType.Squeezed,
-                5 or 6 or 7 or 8 => CompressionType.Crunched,
-                9 => CompressionType.Squashed,
-                10 => CompressionType.Crushed,
-                11 => CompressionType.Distilled,
-                _ => CompressionType.Unknown,
-            };
-        }
-
-        public static DateTime ConvertToDateTime(long rawDateTime)
-        {
-            // Convert Unix timestamp to DateTime (UTC)
-            return DateTimeOffset.FromUnixTimeSeconds(rawDateTime).UtcDateTime;
-        }
+    public static DateTime ConvertToDateTime(long rawDateTime)
+    {
+        // Convert Unix timestamp to DateTime (UTC)
+        return DateTimeOffset.FromUnixTimeSeconds(rawDateTime).UtcDateTime;
     }
 }

src/SharpCompress/Common/Arc/ArcFilePart.cs

@@ -13,63 +13,55 @@ using SharpCompress.Compressors.RLE90;
 using SharpCompress.Compressors.Squeezed;
 using SharpCompress.IO;
 
-namespace SharpCompress.Common.Arc
+namespace SharpCompress.Common.Arc;
+
+public class ArcFilePart : FilePart
 {
-    public class ArcFilePart : FilePart
+    private readonly Stream? _stream;
+
+    internal ArcFilePart(ArcEntryHeader localArcHeader, Stream? seekableStream)
+        : base(localArcHeader.ArchiveEncoding)
     {
-        private readonly Stream? _stream;
-
-        internal ArcFilePart(ArcEntryHeader localArcHeader, Stream? seekableStream)
-            : base(localArcHeader.ArchiveEncoding)
-        {
-            _stream = seekableStream;
-            Header = localArcHeader;
-        }
-
-        internal ArcEntryHeader Header { get; set; }
-
-        internal override string? FilePartName => Header.Name;
-
-        internal override Stream GetCompressedStream()
-        {
-            if (_stream != null)
-            {
-                Stream compressedStream;
-                switch (Header.CompressionMethod)
-                {
-                    case CompressionType.None:
-                        compressedStream = new ReadOnlySubStream(
-                            _stream,
-                            Header.DataStartPosition,
-                            Header.CompressedSize
-                        );
-                        break;
-                    case CompressionType.RLE90:
-                        compressedStream = new RunLength90Stream(
-                            _stream,
-                            (int)Header.CompressedSize
-                        );
-                        break;
-                    case CompressionType.Squeezed:
-                        compressedStream = new SqueezeStream(_stream, (int)Header.CompressedSize);
-                        break;
-                    case CompressionType.Crunched:
-                        compressedStream = new ArcLzwStream(
-                            _stream,
-                            (int)Header.CompressedSize,
-                            true
-                        );
-                        break;
-                    default:
-                        throw new NotSupportedException(
-                            "CompressionMethod: " + Header.CompressionMethod
-                        );
-                }
-                return compressedStream;
-            }
-            return _stream.NotNull();
-        }
-
-        internal override Stream? GetRawStream() => _stream;
+        _stream = seekableStream;
+        Header = localArcHeader;
     }
+
+    internal ArcEntryHeader Header { get; set; }
+
+    internal override string? FilePartName => Header.Name;
+
+    internal override Stream GetCompressedStream()
+    {
+        if (_stream != null)
+        {
+            Stream compressedStream;
+            switch (Header.CompressionMethod)
+            {
+                case CompressionType.None:
+                    compressedStream = new ReadOnlySubStream(
+                        _stream,
+                        Header.DataStartPosition,
+                        Header.CompressedSize
+                    );
+                    break;
+                case CompressionType.RLE90:
+                    compressedStream = new RunLength90Stream(_stream, (int)Header.CompressedSize);
+                    break;
+                case CompressionType.Squeezed:
+                    compressedStream = new SqueezeStream(_stream, (int)Header.CompressedSize);
+                    break;
+                case CompressionType.Crunched:
+                    compressedStream = new ArcLzwStream(_stream, (int)Header.CompressedSize, true);
+                    break;
+                default:
+                    throw new NotSupportedException(
+                        "CompressionMethod: " + Header.CompressionMethod
+                    );
+            }
+            return compressedStream;
+        }
+        return _stream.NotNull();
+    }
+
+    internal override Stream? GetRawStream() => _stream;
 }

src/SharpCompress/Common/Arc/ArcVolume.cs

@@ -6,11 +6,10 @@ using System.Text;
 using System.Threading.Tasks;
 using SharpCompress.Readers;
 
-namespace SharpCompress.Common.Arc
+namespace SharpCompress.Common.Arc;
+
+public class ArcVolume : Volume
 {
-    public class ArcVolume : Volume
-    {
-        public ArcVolume(Stream stream, ReaderOptions readerOptions, int index = 0)
-            : base(stream, readerOptions, index) { }
-    }
+    public ArcVolume(Stream stream, ReaderOptions readerOptions, int index = 0)
+        : base(stream, readerOptions, index) { }
 }

src/SharpCompress/Common/EntryStream.cs

@@ -1,8 +1,6 @@
 using System;
 using System.IO;
 using System.IO.Compression;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.IO;
 using SharpCompress.Readers;
 
@@ -53,15 +51,6 @@ public class EntryStream : Stream, IStreamStack
         _completed = true;
     }
 
-    /// <summary>
-    /// Asynchronously skip the rest of the entry stream.
-    /// </summary>
-    public async Task SkipEntryAsync(CancellationToken cancellationToken = default)
-    {
-        await this.SkipAsync(cancellationToken).ConfigureAwait(false);
-        _completed = true;
-    }
-
     protected override void Dispose(bool disposing)
     {
         if (!(_completed || _reader.Cancelled))
@@ -94,40 +83,6 @@ public class EntryStream : Stream, IStreamStack
         _stream.Dispose();
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask DisposeAsync()
-    {
-        if (!(_completed || _reader.Cancelled))
-        {
-            await SkipEntryAsync().ConfigureAwait(false);
-        }
-
-        //Need a safe standard approach to this - it's okay for compression to overreads. Handling needs to be standardised
-        if (_stream is IStreamStack ss)
-        {
-            if (ss.BaseStream() is SharpCompress.Compressors.Deflate.DeflateStream deflateStream)
-            {
-                await deflateStream.FlushAsync().ConfigureAwait(false);
-            }
-            else if (ss.BaseStream() is SharpCompress.Compressors.LZMA.LzmaStream lzmaStream)
-            {
-                await lzmaStream.FlushAsync().ConfigureAwait(false);
-            }
-        }
-
-        if (_isDisposed)
-        {
-            return;
-        }
-        _isDisposed = true;
-#if DEBUG_STREAMS
-        this.DebugDispose(typeof(EntryStream));
-#endif
-        await base.DisposeAsync().ConfigureAwait(false);
-        await _stream.DisposeAsync().ConfigureAwait(false);
-    }
-#endif
-
     public override bool CanRead => true;
 
     public override bool CanSeek => false;
@@ -136,8 +91,6 @@ public class EntryStream : Stream, IStreamStack
 
     public override void Flush() { }
 
-    public override Task FlushAsync(CancellationToken cancellationToken) => Task.CompletedTask;
-
     public override long Length => _stream.Length;
 
     public override long Position
@@ -156,38 +109,6 @@ public class EntryStream : Stream, IStreamStack
         return read;
     }
 
-    public override async Task<int> ReadAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        CancellationToken cancellationToken
-    )
-    {
-        var read = await _stream
-            .ReadAsync(buffer, offset, count, cancellationToken)
-            .ConfigureAwait(false);
-        if (read <= 0)
-        {
-            _completed = true;
-        }
-        return read;
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask<int> ReadAsync(
-        Memory<byte> buffer,
-        CancellationToken cancellationToken = default
-    )
-    {
-        var read = await _stream.ReadAsync(buffer, cancellationToken).ConfigureAwait(false);
-        if (read <= 0)
-        {
-            _completed = true;
-        }
-        return read;
-    }
-#endif
-
     public override int ReadByte()
     {
         var value = _stream.ReadByte();

src/SharpCompress/Common/ExtractionMethods.cs

@@ -1,7 +1,5 @@
 using System;
 using System.IO;
-using System.Threading;
-using System.Threading.Tasks;
 
 namespace SharpCompress.Common;
 
@@ -118,115 +116,4 @@ internal static class ExtractionMethods
             entry.PreserveExtractionOptions(destinationFileName, options);
         }
     }
-
-    public static async Task WriteEntryToDirectoryAsync(
-        IEntry entry,
-        string destinationDirectory,
-        ExtractionOptions? options,
-        Func<string, ExtractionOptions?, Task> writeAsync,
-        CancellationToken cancellationToken = default
-    )
-    {
-        string destinationFileName;
-        var 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 };
-
-        var file = Path.GetFileName(entry.Key.NotNull("Entry Key is null")).NotNull("File is null");
-        file = Utility.ReplaceInvalidFileNameChars(file);
-        if (options.ExtractFullPath)
-        {
-            var folder = Path.GetDirectoryName(entry.Key.NotNull("Entry Key is null"))
-                .NotNull("Directory is null");
-            var destdir = Path.GetFullPath(Path.Combine(fullDestinationDirectoryPath, folder));
-
-            if (!Directory.Exists(destdir))
-            {
-                if (!destdir.StartsWith(fullDestinationDirectoryPath, StringComparison.Ordinal))
-                {
-                    throw new ExtractionException(
-                        "Entry is trying to create a directory outside of the destination directory."
-                    );
-                }
-
-                Directory.CreateDirectory(destdir);
-            }
-            destinationFileName = Path.Combine(destdir, file);
-        }
-        else
-        {
-            destinationFileName = Path.Combine(fullDestinationDirectoryPath, file);
-        }
-
-        if (!entry.IsDirectory)
-        {
-            destinationFileName = Path.GetFullPath(destinationFileName);
-
-            if (
-                !destinationFileName.StartsWith(
-                    fullDestinationDirectoryPath,
-                    StringComparison.Ordinal
-                )
-            )
-            {
-                throw new ExtractionException(
-                    "Entry is trying to write a file outside of the destination directory."
-                );
-            }
-            await writeAsync(destinationFileName, options).ConfigureAwait(false);
-        }
-        else if (options.ExtractFullPath && !Directory.Exists(destinationFileName))
-        {
-            Directory.CreateDirectory(destinationFileName);
-        }
-    }
-
-    public static async Task WriteEntryToFileAsync(
-        IEntry entry,
-        string destinationFileName,
-        ExtractionOptions? options,
-        Func<string, FileMode, Task> openAndWriteAsync,
-        CancellationToken cancellationToken = default
-    )
-    {
-        if (entry.LinkTarget != null)
-        {
-            if (options?.WriteSymbolicLink is null)
-            {
-                throw new ExtractionException(
-                    "Entry is a symbolic link but ExtractionOptions.WriteSymbolicLink delegate is null"
-                );
-            }
-            options.WriteSymbolicLink(destinationFileName, entry.LinkTarget);
-        }
-        else
-        {
-            var fm = FileMode.Create;
-            options ??= new ExtractionOptions() { Overwrite = true };
-
-            if (!options.Overwrite)
-            {
-                fm = FileMode.CreateNew;
-            }
-
-            await openAndWriteAsync(destinationFileName, fm).ConfigureAwait(false);
-            entry.PreserveExtractionOptions(destinationFileName, options);
-        }
-    }
 }

src/SharpCompress/Common/Tar/TarReadOnlySubStream.cs

@@ -66,36 +66,6 @@ internal class TarReadOnlySubStream : SharpCompressStream, IStreamStack
         base.Dispose(disposing);
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async System.Threading.Tasks.ValueTask DisposeAsync()
-    {
-        if (_isDisposed)
-        {
-            return;
-        }
-
-        _isDisposed = true;
-#if DEBUG_STREAMS
-        this.DebugDispose(typeof(TarReadOnlySubStream));
-#endif
-        // Ensure we read all remaining blocks for this entry.
-        await Stream.SkipAsync(BytesLeftToRead).ConfigureAwait(false);
-        _amountRead += BytesLeftToRead;
-
-        // If the last block wasn't a full 512 bytes, skip the remaining padding bytes.
-        var bytesInLastBlock = _amountRead % 512;
-
-        if (bytesInLastBlock != 0)
-        {
-            await Stream.SkipAsync(512 - bytesInLastBlock).ConfigureAwait(false);
-        }
-
-        // Call base Dispose instead of base DisposeAsync to avoid double disposal
-        base.Dispose(true);
-        GC.SuppressFinalize(this);
-    }
-#endif
-
     private long BytesLeftToRead { get; set; }
 
     public override bool CanRead => true;
@@ -106,10 +76,6 @@ internal class TarReadOnlySubStream : SharpCompressStream, IStreamStack
 
     public override void Flush() { }
 
-    public override System.Threading.Tasks.Task FlushAsync(
-        System.Threading.CancellationToken cancellationToken
-    ) => System.Threading.Tasks.Task.CompletedTask;
-
     public override long Length => throw new NotSupportedException();
 
     public override long Position
@@ -148,48 +114,6 @@ internal class TarReadOnlySubStream : SharpCompressStream, IStreamStack
         return value;
     }
 
-    public override async System.Threading.Tasks.Task<int> ReadAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        System.Threading.CancellationToken cancellationToken
-    )
-    {
-        if (BytesLeftToRead < count)
-        {
-            count = (int)BytesLeftToRead;
-        }
-        var read = await Stream
-            .ReadAsync(buffer, offset, count, cancellationToken)
-            .ConfigureAwait(false);
-        if (read > 0)
-        {
-            BytesLeftToRead -= read;
-            _amountRead += read;
-        }
-        return read;
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async System.Threading.Tasks.ValueTask<int> ReadAsync(
-        System.Memory<byte> buffer,
-        System.Threading.CancellationToken cancellationToken = default
-    )
-    {
-        if (BytesLeftToRead < buffer.Length)
-        {
-            buffer = buffer.Slice(0, (int)BytesLeftToRead);
-        }
-        var read = await Stream.ReadAsync(buffer, cancellationToken).ConfigureAwait(false);
-        if (read > 0)
-        {
-            BytesLeftToRead -= read;
-            _amountRead += read;
-        }
-        return read;
-    }
-#endif
-
     public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
 
     public override void SetLength(long value) => throw new NotSupportedException();

src/SharpCompress/Common/Zip/Headers/ZipFileEntry.cs

@@ -91,15 +91,8 @@ internal abstract class ZipFileEntry : ZipHeader
 
     protected void LoadExtra(byte[] extra)
     {
-        for (var i = 0; i < extra.Length; )
+        for (var i = 0; i < extra.Length - 4; )
         {
-            // Ensure we have at least a header (2-byte ID + 2-byte length)
-            if (i + 4 > extra.Length)
-            {
-                // Incomplete header — stop parsing extras
-                break;
-            }
-
             var type = (ExtraDataType)BinaryPrimitives.ReadUInt16LittleEndian(extra.AsSpan(i));
             if (!Enum.IsDefined(typeof(ExtraDataType), type))
             {
@@ -113,17 +106,7 @@ internal abstract class ZipFileEntry : ZipHeader
             if (length > extra.Length)
             {
                 // bad extras block
-                break; // allow processing optional other blocks
-            }
-            // Some ZIP files contain vendor-specific or malformed extra fields where the declared
-            // data length extends beyond the remaining buffer. This adjustment ensures that
-            // we only read data within bounds (i + 4 + length <= extra.Length)
-            // The example here is: 41 43 18 00 41 52 43 30 46 EB FF FF 51 29 03 C6 03 00 00 00 00 00 00 00 00
-            // No existing zip utility uses 0x4341 ('AC')
-            if (i + 4 + length > extra.Length)
-            {
-                // incomplete or corrupt field
-                break; // allow processing optional other blocks
+                return;
             }
 
             var data = new byte[length];

src/SharpCompress/Common/Zip/ZipFilePart.cs

@@ -13,8 +13,8 @@ using SharpCompress.Compressors.PPMd;
 using SharpCompress.Compressors.Reduce;
 using SharpCompress.Compressors.Shrink;
 using SharpCompress.Compressors.Xz;
+using SharpCompress.Compressors.ZStandard;
 using SharpCompress.IO;
-using ZstdSharp;
 
 namespace SharpCompress.Common.Zip;
 

src/SharpCompress/Compressors/Deflate/DeflateStream.cs

@@ -28,7 +28,6 @@ using System;
 using System.IO;
 using System.Text;
 using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.IO;
 
 namespace SharpCompress.Compressors.Deflate;
@@ -290,34 +289,6 @@ public class DeflateStream : Stream, IStreamStack
         _baseStream.Flush();
     }
 
-    public override async Task FlushAsync(CancellationToken cancellationToken)
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("DeflateStream");
-        }
-        await _baseStream.FlushAsync(cancellationToken).ConfigureAwait(false);
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask DisposeAsync()
-    {
-        if (_disposed)
-        {
-            return;
-        }
-        _disposed = true;
-        if (_baseStream != null)
-        {
-            await _baseStream.DisposeAsync().ConfigureAwait(false);
-        }
-#if DEBUG_STREAMS
-        this.DebugDispose(typeof(DeflateStream));
-#endif
-        await base.DisposeAsync().ConfigureAwait(false);
-    }
-#endif
-
     /// <summary>
     /// Read data from the stream.
     /// </summary>
@@ -354,36 +325,6 @@ public class DeflateStream : Stream, IStreamStack
         return _baseStream.Read(buffer, offset, count);
     }
 
-    public override async Task<int> ReadAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        CancellationToken cancellationToken
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("DeflateStream");
-        }
-        return await _baseStream
-            .ReadAsync(buffer, offset, count, cancellationToken)
-            .ConfigureAwait(false);
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask<int> ReadAsync(
-        Memory<byte> buffer,
-        CancellationToken cancellationToken = default
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("DeflateStream");
-        }
-        return await _baseStream.ReadAsync(buffer, cancellationToken).ConfigureAwait(false);
-    }
-#endif
-
     public override int ReadByte()
     {
         if (_disposed)
@@ -445,36 +386,6 @@ public class DeflateStream : Stream, IStreamStack
         _baseStream.Write(buffer, offset, count);
     }
 
-    public override async Task WriteAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        CancellationToken cancellationToken
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("DeflateStream");
-        }
-        await _baseStream
-            .WriteAsync(buffer, offset, count, cancellationToken)
-            .ConfigureAwait(false);
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask WriteAsync(
-        ReadOnlyMemory<byte> buffer,
-        CancellationToken cancellationToken = default
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("DeflateStream");
-        }
-        await _baseStream.WriteAsync(buffer, cancellationToken).ConfigureAwait(false);
-    }
-#endif
-
     public override void WriteByte(byte value)
     {
         if (_disposed)

src/SharpCompress/Compressors/Deflate/GZipStream.cs

@@ -30,8 +30,6 @@ using System;
 using System.Buffers.Binary;
 using System.IO;
 using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.IO;
 
 namespace SharpCompress.Compressors.Deflate;
@@ -259,15 +257,6 @@ public class GZipStream : Stream, IStreamStack
         BaseStream.Flush();
     }
 
-    public override async Task FlushAsync(CancellationToken cancellationToken)
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("GZipStream");
-        }
-        await BaseStream.FlushAsync(cancellationToken).ConfigureAwait(false);
-    }
-
     /// <summary>
     ///   Read and decompress data from the source stream.
     /// </summary>
@@ -320,54 +309,6 @@ public class GZipStream : Stream, IStreamStack
         return n;
     }
 
-    public override async Task<int> ReadAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        CancellationToken cancellationToken
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("GZipStream");
-        }
-        var n = await BaseStream
-            .ReadAsync(buffer, offset, count, cancellationToken)
-            .ConfigureAwait(false);
-
-        if (!_firstReadDone)
-        {
-            _firstReadDone = true;
-            FileName = BaseStream._GzipFileName;
-            Comment = BaseStream._GzipComment;
-            LastModified = BaseStream._GzipMtime;
-        }
-        return n;
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask<int> ReadAsync(
-        Memory<byte> buffer,
-        CancellationToken cancellationToken = default
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("GZipStream");
-        }
-        var n = await BaseStream.ReadAsync(buffer, cancellationToken).ConfigureAwait(false);
-
-        if (!_firstReadDone)
-        {
-            _firstReadDone = true;
-            FileName = BaseStream._GzipFileName;
-            Comment = BaseStream._GzipComment;
-            LastModified = BaseStream._GzipMtime;
-        }
-        return n;
-    }
-#endif
-
     /// <summary>
     ///   Calling this method always throws a <see cref="NotImplementedException"/>.
     /// </summary>
@@ -427,77 +368,6 @@ public class GZipStream : Stream, IStreamStack
         BaseStream.Write(buffer, offset, count);
     }
 
-    public override async Task WriteAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        CancellationToken cancellationToken
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("GZipStream");
-        }
-        if (BaseStream._streamMode == ZlibBaseStream.StreamMode.Undefined)
-        {
-            if (BaseStream._wantCompress)
-            {
-                // first write in compression, therefore, emit the GZIP header
-                _headerByteCount = EmitHeader();
-            }
-            else
-            {
-                throw new InvalidOperationException();
-            }
-        }
-
-        await BaseStream.WriteAsync(buffer, offset, count, cancellationToken).ConfigureAwait(false);
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask WriteAsync(
-        ReadOnlyMemory<byte> buffer,
-        CancellationToken cancellationToken = default
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("GZipStream");
-        }
-        if (BaseStream._streamMode == ZlibBaseStream.StreamMode.Undefined)
-        {
-            if (BaseStream._wantCompress)
-            {
-                // first write in compression, therefore, emit the GZIP header
-                _headerByteCount = EmitHeader();
-            }
-            else
-            {
-                throw new InvalidOperationException();
-            }
-        }
-
-        await BaseStream.WriteAsync(buffer, cancellationToken).ConfigureAwait(false);
-    }
-
-    public override async ValueTask DisposeAsync()
-    {
-        if (_disposed)
-        {
-            return;
-        }
-        _disposed = true;
-        if (BaseStream != null)
-        {
-            await BaseStream.DisposeAsync().ConfigureAwait(false);
-        }
-#if DEBUG_STREAMS
-        this.DebugDispose(typeof(GZipStream));
-#endif
-        await base.DisposeAsync().ConfigureAwait(false);
-    }
-#endif
-
     #endregion Stream methods
 
     public string? Comment

src/SharpCompress/Compressors/Deflate/ZlibBaseStream.cs

@@ -31,8 +31,6 @@ using System.Buffers.Binary;
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common.Tar.Headers;
 using SharpCompress.IO;
 
@@ -199,69 +197,6 @@ internal class ZlibBaseStream : Stream, IStreamStack
         } while (!done);
     }
 
-    public override async Task WriteAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        CancellationToken cancellationToken
-    )
-    {
-        // workitem 7159
-        // calculate the CRC on the unccompressed data  (before writing)
-        if (crc != null)
-        {
-            crc.SlurpBlock(buffer, offset, count);
-        }
-
-        if (_streamMode == StreamMode.Undefined)
-        {
-            _streamMode = StreamMode.Writer;
-        }
-        else if (_streamMode != StreamMode.Writer)
-        {
-            throw new ZlibException("Cannot Write after Reading.");
-        }
-
-        if (count == 0)
-        {
-            return;
-        }
-
-        // first reference of z property will initialize the private var _z
-        z.InputBuffer = buffer;
-        _z.NextIn = offset;
-        _z.AvailableBytesIn = count;
-        var done = false;
-        do
-        {
-            _z.OutputBuffer = workingBuffer;
-            _z.NextOut = 0;
-            _z.AvailableBytesOut = _workingBuffer.Length;
-            var rc = (_wantCompress) ? _z.Deflate(_flushMode) : _z.Inflate(_flushMode);
-            if (rc != ZlibConstants.Z_OK && rc != ZlibConstants.Z_STREAM_END)
-            {
-                throw new ZlibException((_wantCompress ? "de" : "in") + "flating: " + _z.Message);
-            }
-
-            await _stream
-                .WriteAsync(
-                    _workingBuffer,
-                    0,
-                    _workingBuffer.Length - _z.AvailableBytesOut,
-                    cancellationToken
-                )
-                .ConfigureAwait(false);
-
-            done = _z.AvailableBytesIn == 0 && _z.AvailableBytesOut != 0;
-
-            // If GZIP and de-compress, we're done when 8 bytes remain.
-            if (_flavor == ZlibStreamFlavor.GZIP && !_wantCompress)
-            {
-                done = (_z.AvailableBytesIn == 8 && _z.AvailableBytesOut != 0);
-            }
-        } while (!done);
-    }
-
     private void finish()
     {
         if (_z is null)
@@ -400,111 +335,6 @@ internal class ZlibBaseStream : Stream, IStreamStack
         }
     }
 
-    private async Task finishAsync(CancellationToken cancellationToken = default)
-    {
-        if (_z is null)
-        {
-            return;
-        }
-
-        if (_streamMode == StreamMode.Writer)
-        {
-            var done = false;
-            do
-            {
-                _z.OutputBuffer = workingBuffer;
-                _z.NextOut = 0;
-                _z.AvailableBytesOut = _workingBuffer.Length;
-                var rc =
-                    (_wantCompress) ? _z.Deflate(FlushType.Finish) : _z.Inflate(FlushType.Finish);
-
-                if (rc != ZlibConstants.Z_STREAM_END && rc != ZlibConstants.Z_OK)
-                {
-                    var verb = (_wantCompress ? "de" : "in") + "flating";
-                    if (_z.Message is null)
-                    {
-                        throw new ZlibException(String.Format("{0}: (rc = {1})", verb, rc));
-                    }
-                    throw new ZlibException(verb + ": " + _z.Message);
-                }
-
-                if (_workingBuffer.Length - _z.AvailableBytesOut > 0)
-                {
-                    await _stream
-                        .WriteAsync(
-                            _workingBuffer,
-                            0,
-                            _workingBuffer.Length - _z.AvailableBytesOut,
-                            cancellationToken
-                        )
-                        .ConfigureAwait(false);
-                }
-
-                done = _z.AvailableBytesIn == 0 && _z.AvailableBytesOut != 0;
-
-                // If GZIP and de-compress, we're done when 8 bytes remain.
-                if (_flavor == ZlibStreamFlavor.GZIP && !_wantCompress)
-                {
-                    done = (_z.AvailableBytesIn == 8 && _z.AvailableBytesOut != 0);
-                }
-            } while (!done);
-
-            await FlushAsync(cancellationToken).ConfigureAwait(false);
-
-            // workitem 7159
-            if (_flavor == ZlibStreamFlavor.GZIP)
-            {
-                if (_wantCompress)
-                {
-                    // Emit the GZIP trailer: CRC32 and  size mod 2^32
-                    byte[] intBuf = new byte[4];
-                    BinaryPrimitives.WriteInt32LittleEndian(intBuf, crc.Crc32Result);
-                    await _stream.WriteAsync(intBuf, 0, 4, cancellationToken).ConfigureAwait(false);
-                    var c2 = (int)(crc.TotalBytesRead & 0x00000000FFFFFFFF);
-                    BinaryPrimitives.WriteInt32LittleEndian(intBuf, c2);
-                    await _stream.WriteAsync(intBuf, 0, 4, cancellationToken).ConfigureAwait(false);
-                }
-                else
-                {
-                    throw new ZlibException("Writing with decompression is not supported.");
-                }
-            }
-        }
-        // workitem 7159
-        else if (_streamMode == StreamMode.Reader)
-        {
-            if (_flavor == ZlibStreamFlavor.GZIP)
-            {
-                if (!_wantCompress)
-                {
-                    // workitem 8501: handle edge case (decompress empty stream)
-                    if (_z.TotalBytesOut == 0L)
-                    {
-                        return;
-                    }
-
-                    // Read and potentially verify the GZIP trailer: CRC32 and  size mod 2^32
-                    byte[] trailer = new byte[8];
-
-                    // workitem 8679
-                    if (_z.AvailableBytesIn != 8)
-                    {
-                        // Make sure we have read to the end of the stream
-                        _z.InputBuffer.AsSpan(_z.NextIn, _z.AvailableBytesIn).CopyTo(trailer);
-                        var bytesNeeded = 8 - _z.AvailableBytesIn;
-                        var bytesRead = await _stream
-                            .ReadAsync(trailer, _z.AvailableBytesIn, bytesNeeded, cancellationToken)
-                            .ConfigureAwait(false);
-                    }
-                }
-                else
-                {
-                    throw new ZlibException("Reading with compression is not supported.");
-                }
-            }
-        }
-    }
-
     private void end()
     {
         if (z is null)
@@ -552,38 +382,6 @@ internal class ZlibBaseStream : Stream, IStreamStack
         }
     }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask DisposeAsync()
-    {
-        if (isDisposed)
-        {
-            return;
-        }
-        isDisposed = true;
-#if DEBUG_STREAMS
-        this.DebugDispose(typeof(ZlibBaseStream));
-#endif
-        await base.DisposeAsync().ConfigureAwait(false);
-        if (_stream is null)
-        {
-            return;
-        }
-        try
-        {
-            await finishAsync().ConfigureAwait(false);
-        }
-        finally
-        {
-            end();
-            if (_stream != null)
-            {
-                await _stream.DisposeAsync().ConfigureAwait(false);
-                _stream = null;
-            }
-        }
-    }
-#endif
-
     public override void Flush()
     {
         _stream.Flush();
@@ -592,14 +390,6 @@ internal class ZlibBaseStream : Stream, IStreamStack
         z.AvailableBytesIn = 0;
     }
 
-    public override async Task FlushAsync(CancellationToken cancellationToken)
-    {
-        await _stream.FlushAsync(cancellationToken).ConfigureAwait(false);
-        //rewind the buffer
-        ((IStreamStack)this).Rewind(z.AvailableBytesIn); //unused
-        z.AvailableBytesIn = 0;
-    }
-
     public override Int64 Seek(Int64 offset, SeekOrigin origin) =>
         throw new NotSupportedException();
 
@@ -646,31 +436,6 @@ internal class ZlibBaseStream : Stream, IStreamStack
         return _encoding.GetString(buffer, 0, buffer.Length);
     }
 
-    private async Task<string> ReadZeroTerminatedStringAsync(CancellationToken cancellationToken)
-    {
-        var list = new List<byte>();
-        var done = false;
-        do
-        {
-            // workitem 7740
-            var n = await _stream.ReadAsync(_buf1, 0, 1, cancellationToken).ConfigureAwait(false);
-            if (n != 1)
-            {
-                throw new ZlibException("Unexpected EOF reading GZIP header.");
-            }
-            if (_buf1[0] == 0)
-            {
-                done = true;
-            }
-            else
-            {
-                list.Add(_buf1[0]);
-            }
-        } while (!done);
-        var buffer = list.ToArray();
-        return _encoding.GetString(buffer, 0, buffer.Length);
-    }
-
     private int _ReadAndValidateGzipHeader()
     {
         var totalBytesRead = 0;
@@ -729,68 +494,6 @@ internal class ZlibBaseStream : Stream, IStreamStack
         return totalBytesRead;
     }
 
-    private async Task<int> _ReadAndValidateGzipHeaderAsync(CancellationToken cancellationToken)
-    {
-        var totalBytesRead = 0;
-
-        // read the header on the first read
-        byte[] header = new byte[10];
-        var n = await _stream.ReadAsync(header, 0, 10, cancellationToken).ConfigureAwait(false);
-
-        // workitem 8501: handle edge case (decompress empty stream)
-        if (n == 0)
-        {
-            return 0;
-        }
-
-        if (n != 10)
-        {
-            throw new ZlibException("Not a valid GZIP stream.");
-        }
-
-        if (header[0] != 0x1F || header[1] != 0x8B || header[2] != 8)
-        {
-            throw new ZlibException("Bad GZIP header.");
-        }
-
-        var timet = BinaryPrimitives.ReadInt32LittleEndian(header.AsSpan(4));
-        _GzipMtime = TarHeader.EPOCH.AddSeconds(timet);
-        totalBytesRead += n;
-        if ((header[3] & 0x04) == 0x04)
-        {
-            // read and discard extra field
-            n = await _stream.ReadAsync(header, 0, 2, cancellationToken).ConfigureAwait(false); // 2-byte length field
-            totalBytesRead += n;
-
-            var extraLength = (short)(header[0] + header[1] * 256);
-            var extra = new byte[extraLength];
-            n = await _stream
-                .ReadAsync(extra, 0, extra.Length, cancellationToken)
-                .ConfigureAwait(false);
-            if (n != extraLength)
-            {
-                throw new ZlibException("Unexpected end-of-file reading GZIP header.");
-            }
-            totalBytesRead += n;
-        }
-        if ((header[3] & 0x08) == 0x08)
-        {
-            _GzipFileName = await ReadZeroTerminatedStringAsync(cancellationToken)
-                .ConfigureAwait(false);
-        }
-        if ((header[3] & 0x10) == 0x010)
-        {
-            _GzipComment = await ReadZeroTerminatedStringAsync(cancellationToken)
-                .ConfigureAwait(false);
-        }
-        if ((header[3] & 0x02) == 0x02)
-        {
-            await _stream.ReadAsync(_buf1, 0, 1, cancellationToken).ConfigureAwait(false); // CRC16, ignore
-        }
-
-        return totalBytesRead;
-    }
-
     public override Int32 Read(Byte[] buffer, Int32 offset, Int32 count)
     {
         // According to MS documentation, any implementation of the IO.Stream.Read function must:
@@ -975,220 +678,6 @@ internal class ZlibBaseStream : Stream, IStreamStack
         return rc;
     }
 
-    public override async Task<int> ReadAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        CancellationToken cancellationToken
-    )
-    {
-        // According to MS documentation, any implementation of the IO.Stream.Read function must:
-        // (a) throw an exception if offset & count reference an invalid part of the buffer,
-        //     or if count < 0, or if buffer is null
-        // (b) return 0 only upon EOF, or if count = 0
-        // (c) if not EOF, then return at least 1 byte, up to <count> bytes
-
-        if (_streamMode == StreamMode.Undefined)
-        {
-            if (!_stream.CanRead)
-            {
-                throw new ZlibException("The stream is not readable.");
-            }
-
-            // for the first read, set up some controls.
-            _streamMode = StreamMode.Reader;
-
-            // (The first reference to _z goes through the private accessor which
-            // may initialize it.)
-            z.AvailableBytesIn = 0;
-            if (_flavor == ZlibStreamFlavor.GZIP)
-            {
-                _gzipHeaderByteCount = await _ReadAndValidateGzipHeaderAsync(cancellationToken)
-                    .ConfigureAwait(false);
-
-                // workitem 8501: handle edge case (decompress empty stream)
-                if (_gzipHeaderByteCount == 0)
-                {
-                    return 0;
-                }
-            }
-        }
-
-        if (_streamMode != StreamMode.Reader)
-        {
-            throw new ZlibException("Cannot Read after Writing.");
-        }
-
-        var 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)
-        {
-            // 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)
-        {
-            throw new ArgumentNullException(nameof(buffer));
-        }
-        if (count < 0)
-        {
-            throw new ArgumentOutOfRangeException(nameof(count));
-        }
-        if (offset < buffer.GetLowerBound(0))
-        {
-            throw new ArgumentOutOfRangeException(nameof(offset));
-        }
-        if ((offset + count) > buffer.GetLength(0))
-        {
-            throw new ArgumentOutOfRangeException(nameof(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.)
-        _z.InputBuffer = workingBuffer;
-
-        do
-        {
-            // need data in _workingBuffer in order to deflate/inflate.  Here, we check if we have any.
-            if ((_z.AvailableBytesIn == 0) && (!nomoreinput))
-            {
-                // No data available, so try to Read data from the captive stream.
-                _z.NextIn = 0;
-                _z.AvailableBytesIn = await _stream
-                    .ReadAsync(_workingBuffer, 0, _workingBuffer.Length, cancellationToken)
-                    .ConfigureAwait(false);
-                if (_z.AvailableBytesIn == 0)
-                {
-                    nomoreinput = true;
-                }
-            }
-
-            // we have data in InputBuffer; now compress or decompress as appropriate
-            rc = (_wantCompress) ? _z.Deflate(_flushMode) : _z.Inflate(_flushMode);
-
-            if (nomoreinput && (rc == ZlibConstants.Z_BUF_ERROR))
-            {
-                return 0;
-            }
-
-            if (rc != ZlibConstants.Z_OK && rc != ZlibConstants.Z_STREAM_END)
-            {
-                throw new ZlibException(
-                    String.Format(
-                        "{0}flating:  rc={1}  msg={2}",
-                        (_wantCompress ? "de" : "in"),
-                        rc,
-                        _z.Message
-                    )
-                );
-            }
-
-            if (
-                (nomoreinput || rc == ZlibConstants.Z_STREAM_END) && (_z.AvailableBytesOut == count)
-            )
-            {
-                break; // nothing more to read
-            }
-        } //while (_z.AvailableBytesOut == count && rc == ZlibConstants.Z_OK);
-        while (_z.AvailableBytesOut > 0 && !nomoreinput && rc == ZlibConstants.Z_OK);
-
-        // workitem 8557
-        // is there more room in output?
-        if (_z.AvailableBytesOut > 0)
-        {
-            if (rc == ZlibConstants.Z_OK && _z.AvailableBytesIn == 0)
-            {
-                // deferred
-            }
-
-            // are we completely done reading?
-            if (nomoreinput)
-            {
-                // and in compression?
-                if (_wantCompress)
-                {
-                    // 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);
-        }
-
-        if (rc == ZlibConstants.Z_STREAM_END && z.AvailableBytesIn != 0 && !_wantCompress)
-        {
-            //rewind the buffer
-            ((IStreamStack)this).Rewind(z.AvailableBytesIn); //unused
-            z.AvailableBytesIn = 0;
-        }
-
-        return rc;
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask<int> ReadAsync(
-        Memory<byte> buffer,
-        CancellationToken cancellationToken = default
-    )
-    {
-        // Use ArrayPool to rent a buffer and delegate to byte[] ReadAsync
-        byte[] array = System.Buffers.ArrayPool<byte>.Shared.Rent(buffer.Length);
-        try
-        {
-            int read = await ReadAsync(array, 0, buffer.Length, cancellationToken)
-                .ConfigureAwait(false);
-            array.AsSpan(0, read).CopyTo(buffer.Span);
-            return read;
-        }
-        finally
-        {
-            System.Buffers.ArrayPool<byte>.Shared.Return(array);
-        }
-    }
-#endif
-
     public override Boolean CanRead => _stream.CanRead;
 
     public override Boolean CanSeek => _stream.CanSeek;

src/SharpCompress/Compressors/Deflate/ZlibStream.cs

@@ -28,8 +28,6 @@
 using System;
 using System.IO;
 using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.IO;
 
 namespace SharpCompress.Compressors.Deflate;
@@ -268,34 +266,6 @@ public class ZlibStream : Stream, IStreamStack
         _baseStream.Flush();
     }
 
-    public override async Task FlushAsync(CancellationToken cancellationToken)
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("ZlibStream");
-        }
-        await _baseStream.FlushAsync(cancellationToken).ConfigureAwait(false);
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask DisposeAsync()
-    {
-        if (_disposed)
-        {
-            return;
-        }
-        _disposed = true;
-        if (_baseStream != null)
-        {
-            await _baseStream.DisposeAsync().ConfigureAwait(false);
-        }
-#if DEBUG_STREAMS
-        this.DebugDispose(typeof(ZlibStream));
-#endif
-        await base.DisposeAsync().ConfigureAwait(false);
-    }
-#endif
-
     /// <summary>
     /// Read data from the stream.
     /// </summary>
@@ -331,36 +301,6 @@ public class ZlibStream : Stream, IStreamStack
         return _baseStream.Read(buffer, offset, count);
     }
 
-    public override async Task<int> ReadAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        CancellationToken cancellationToken
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("ZlibStream");
-        }
-        return await _baseStream
-            .ReadAsync(buffer, offset, count, cancellationToken)
-            .ConfigureAwait(false);
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask<int> ReadAsync(
-        Memory<byte> buffer,
-        CancellationToken cancellationToken = default
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("ZlibStream");
-        }
-        return await _baseStream.ReadAsync(buffer, cancellationToken).ConfigureAwait(false);
-    }
-#endif
-
     public override int ReadByte()
     {
         if (_disposed)
@@ -415,36 +355,6 @@ public class ZlibStream : Stream, IStreamStack
         _baseStream.Write(buffer, offset, count);
     }
 
-    public override async Task WriteAsync(
-        byte[] buffer,
-        int offset,
-        int count,
-        CancellationToken cancellationToken
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("ZlibStream");
-        }
-        await _baseStream
-            .WriteAsync(buffer, offset, count, cancellationToken)
-            .ConfigureAwait(false);
-    }
-
-#if !NETFRAMEWORK && !NETSTANDARD2_0
-    public override async ValueTask WriteAsync(
-        ReadOnlyMemory<byte> buffer,
-        CancellationToken cancellationToken = default
-    )
-    {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException("ZlibStream");
-        }
-        await _baseStream.WriteAsync(buffer, cancellationToken).ConfigureAwait(false);
-    }
-#endif
-
     public override void WriteByte(byte value)
     {
         if (_disposed)

src/SharpCompress/Compressors/Filters/DeltaFilter.cs

@@ -1,36 +1,35 @@
 using System.IO;
 
-namespace SharpCompress.Compressors.Filters
+namespace SharpCompress.Compressors.Filters;
+
+internal class DeltaFilter : Filter
 {
-    internal class DeltaFilter : Filter
+    private const int DISTANCE_MIN = 1;
+    private const int DISTANCE_MAX = 256;
+    private const int DISTANCE_MASK = DISTANCE_MAX - 1;
+
+    private int _distance;
+    private byte[] _history;
+    private int _position;
+
+    public DeltaFilter(bool isEncoder, Stream baseStream, byte[] info)
+        : base(isEncoder, baseStream, 1)
     {
-        private const int DISTANCE_MIN = 1;
-        private const int DISTANCE_MAX = 256;
-        private const int DISTANCE_MASK = DISTANCE_MAX - 1;
+        _distance = info[0];
+        _history = new byte[DISTANCE_MAX];
+        _position = 0;
+    }
 
-        private int _distance;
-        private byte[] _history;
-        private int _position;
+    protected override int Transform(byte[] buffer, int offset, int count)
+    {
+        var end = offset + count;
 
-        public DeltaFilter(bool isEncoder, Stream baseStream, byte[] info)
-            : base(isEncoder, baseStream, 1)
+        for (var i = offset; i < end; i++)
         {
-            _distance = info[0];
-            _history = new byte[DISTANCE_MAX];
-            _position = 0;
+            buffer[i] += _history[(_distance + _position--) & DISTANCE_MASK];
+            _history[_position & DISTANCE_MASK] = buffer[i];
         }
 
-        protected override int Transform(byte[] buffer, int offset, int count)
-        {
-            var end = offset + count;
-
-            for (var i = offset; i < end; i++)
-            {
-                buffer[i] += _history[(_distance + _position--) & DISTANCE_MASK];
-                _history[_position & DISTANCE_MASK] = buffer[i];
-            }
-
-            return count;
-        }
+        return count;
     }
 }

src/SharpCompress/Compressors/LZMA/LZ/LzOutWindow.cs

@@ -1,12 +1,11 @@
 #nullable disable
 
 using System;
-using System.Buffers;
 using System.IO;
 
 namespace SharpCompress.Compressors.LZMA.LZ;
 
-internal class OutWindow : IDisposable
+internal class OutWindow
 {
     private byte[] _buffer;
     private int _windowSize;
@@ -16,22 +15,19 @@ internal class OutWindow : IDisposable
     private int _pendingDist;
     private Stream _stream;
 
-    private long _total;
-    private long _limit;
-
-    public long Total => _total;
+    public long _total;
+    public long _limit;
 
     public void Create(int windowSize)
     {
         if (_windowSize != windowSize)
         {
-            if (_buffer is not null)
-            {
-                ArrayPool<byte>.Shared.Return(_buffer);
-            }
-            _buffer = ArrayPool<byte>.Shared.Rent(windowSize);
+            _buffer = new byte[windowSize];
+        }
+        else
+        {
+            _buffer[windowSize - 1] = 0;
         }
-        _buffer[windowSize - 1] = 0;
         _windowSize = windowSize;
         _pos = 0;
         _streamPos = 0;
@@ -40,22 +36,7 @@ internal class OutWindow : IDisposable
         _limit = 0;
     }
 
-    public void Dispose()
-    {
-        ReleaseStream();
-        if (_buffer is null)
-        {
-            return;
-        }
-        ArrayPool<byte>.Shared.Return(_buffer);
-        _buffer = null;
-    }
-
-    public void Reset()
-    {
-        ReleaseStream();
-        Create(_windowSize);
-    }
+    public void Reset() => Create(_windowSize);
 
     public void Init(Stream stream)
     {
@@ -85,7 +66,7 @@ internal class OutWindow : IDisposable
         _stream = null;
     }
 
-    private void Flush()
+    public void Flush()
     {
         if (_stream is null)
         {

src/SharpCompress/Compressors/LZMA/LzmaDecoder.cs

@@ -294,7 +294,7 @@ public class Decoder : ICoder, ISetDecoderProperties // ,System.IO.Stream
         }
         else
         {
-            _outWindow.SetLimit(long.MaxValue - _outWindow.Total);
+            _outWindow.SetLimit(long.MaxValue - _outWindow._total);
         }
 
         var rangeDecoder = new RangeCoder.Decoder();
@@ -305,7 +305,6 @@ public class Decoder : ICoder, ISetDecoderProperties // ,System.IO.Stream
         _outWindow.ReleaseStream();
         rangeDecoder.ReleaseStream();
 
-        _outWindow.Dispose();
         _outWindow = null;
     }
 
@@ -317,7 +316,7 @@ public class Decoder : ICoder, ISetDecoderProperties // ,System.IO.Stream
 
         while (outWindow.HasSpace)
         {
-            var posState = (uint)outWindow.Total & _posStateMask;
+            var posState = (uint)outWindow._total & _posStateMask;
             if (
                 _isMatchDecoders[(_state._index << Base.K_NUM_POS_STATES_BITS_MAX) + posState]
                     .Decode(rangeDecoder) == 0
@@ -329,14 +328,18 @@ public class Decoder : ICoder, ISetDecoderProperties // ,System.IO.Stream
                 {
                     b = _literalDecoder.DecodeWithMatchByte(
                         rangeDecoder,
-                        (uint)outWindow.Total,
+                        (uint)outWindow._total,
                         prevByte,
                         outWindow.GetByte((int)_rep0)
                     );
                 }
                 else
                 {
-                    b = _literalDecoder.DecodeNormal(rangeDecoder, (uint)outWindow.Total, prevByte);
+                    b = _literalDecoder.DecodeNormal(
+                        rangeDecoder,
+                        (uint)outWindow._total,
+                        prevByte
+                    );
                 }
                 outWindow.PutByte(b);
                 _state.UpdateChar();
@@ -421,7 +424,7 @@ public class Decoder : ICoder, ISetDecoderProperties // ,System.IO.Stream
                         _rep0 = posSlot;
                     }
                 }
-                if (_rep0 >= outWindow.Total || _rep0 >= dictionarySizeCheck)
+                if (_rep0 >= outWindow._total || _rep0 >= dictionarySizeCheck)
                 {
                     if (_rep0 == 0xFFFFFFFF)
                     {

src/SharpCompress/Compressors/LZMA/LzmaStream.cs

@@ -178,7 +178,6 @@ public class LzmaStream : Stream, IStreamStack
                 _position = _encoder.Code(null, true);
             }
             _inputStream?.Dispose();
-            _outWindow.Dispose();
         }
         base.Dispose(disposing);
     }

src/SharpCompress/Compressors/LZMA/Registry.cs

@@ -7,7 +7,7 @@ using SharpCompress.Compressors.Deflate;
 using SharpCompress.Compressors.Filters;
 using SharpCompress.Compressors.LZMA.Utilites;
 using SharpCompress.Compressors.PPMd;
-using ZstdSharp;
+using SharpCompress.Compressors.ZStandard;
 
 namespace SharpCompress.Compressors.LZMA;
 

src/SharpCompress/Compressors/Lzw/LzwConstants.cs

@@ -1,65 +1,64 @@
-namespace SharpCompress.Compressors.Lzw
+namespace SharpCompress.Compressors.Lzw;
+
+/// <summary>
+/// This class contains constants used for LZW
+/// </summary>
+[System.Diagnostics.CodeAnalysis.SuppressMessage(
+    "Naming",
+    "CA1707:Identifiers should not contain underscores",
+    Justification = "kept for backwards compatibility"
+)]
+public sealed class LzwConstants
 {
     /// <summary>
-    /// This class contains constants used for LZW
+    /// Magic number found at start of LZW header: 0x1f 0x9d
     /// </summary>
-    [System.Diagnostics.CodeAnalysis.SuppressMessage(
-        "Naming",
-        "CA1707:Identifiers should not contain underscores",
-        Justification = "kept for backwards compatibility"
-    )]
-    public sealed class LzwConstants
-    {
-        /// <summary>
-        /// Magic number found at start of LZW header: 0x1f 0x9d
-        /// </summary>
-        public const int MAGIC = 0x1f9d;
+    public const int MAGIC = 0x1f9d;
 
-        /// <summary>
-        /// Maximum number of bits per code
-        /// </summary>
-        public const int MAX_BITS = 16;
+    /// <summary>
+    /// Maximum number of bits per code
+    /// </summary>
+    public const int MAX_BITS = 16;
 
-        /* 3rd header byte:
-         * bit 0..4 Number of compression bits
-         * bit 5    Extended header
-         * bit 6    Free
-         * bit 7    Block mode
-         */
+    /* 3rd header byte:
+     * bit 0..4 Number of compression bits
+     * bit 5    Extended header
+     * bit 6    Free
+     * bit 7    Block mode
+     */
 
-        /// <summary>
-        /// Mask for 'number of compression bits'
-        /// </summary>
-        public const int BIT_MASK = 0x1f;
+    /// <summary>
+    /// Mask for 'number of compression bits'
+    /// </summary>
+    public const int BIT_MASK = 0x1f;
 
-        /// <summary>
-        /// Indicates the presence of a fourth header byte
-        /// </summary>
-        public const int EXTENDED_MASK = 0x20;
+    /// <summary>
+    /// Indicates the presence of a fourth header byte
+    /// </summary>
+    public const int EXTENDED_MASK = 0x20;
 
-        //public const int FREE_MASK      = 0x40;
+    //public const int FREE_MASK      = 0x40;
 
-        /// <summary>
-        /// Reserved bits
-        /// </summary>
-        public const int RESERVED_MASK = 0x60;
+    /// <summary>
+    /// Reserved bits
+    /// </summary>
+    public const int RESERVED_MASK = 0x60;
 
-        /// <summary>
-        /// Block compression: if table is full and compression rate is dropping,
-        /// clear the dictionary.
-        /// </summary>
-        public const int BLOCK_MODE_MASK = 0x80;
+    /// <summary>
+    /// Block compression: if table is full and compression rate is dropping,
+    /// clear the dictionary.
+    /// </summary>
+    public const int BLOCK_MODE_MASK = 0x80;
 
-        /// <summary>
-        /// LZW file header size (in bytes)
-        /// </summary>
-        public const int HDR_SIZE = 3;
+    /// <summary>
+    /// LZW file header size (in bytes)
+    /// </summary>
+    public const int HDR_SIZE = 3;
 
-        /// <summary>
-        /// Initial number of bits per code
-        /// </summary>
-        public const int INIT_BITS = 9;
+    /// <summary>
+    /// Initial number of bits per code
+    /// </summary>
+    public const int INIT_BITS = 9;
 
-        private LzwConstants() { }
-    }
+    private LzwConstants() { }
 }

src/SharpCompress/Compressors/RLE90/RLE.cs

@@ -1,52 +1,51 @@
 using System.Collections.Generic;
 using System.Linq;
 
-namespace SharpCompress.Compressors.RLE90
+namespace SharpCompress.Compressors.RLE90;
+
+public static class RLE
 {
-    public static class RLE
+    private const byte DLE = 0x90;
+
+    /// <summary>
+    /// Unpacks an RLE compressed buffer.
+    /// Format: <char> DLE <count>, where count == 0 -> DLE
+    /// </summary>
+    /// <param name="compressedBuffer">The compressed buffer to unpack.</param>
+    /// <returns>A list of unpacked bytes.</returns>
+    public static List<byte> UnpackRLE(byte[] compressedBuffer)
     {
-        private const byte DLE = 0x90;
+        var result = new List<byte>(compressedBuffer.Length * 2); // Optimized initial capacity
+        var countMode = false;
+        byte last = 0;
 
-        /// <summary>
-        /// Unpacks an RLE compressed buffer.
-        /// Format: <char> DLE <count>, where count == 0 -> DLE
-        /// </summary>
-        /// <param name="compressedBuffer">The compressed buffer to unpack.</param>
-        /// <returns>A list of unpacked bytes.</returns>
-        public static List<byte> UnpackRLE(byte[] compressedBuffer)
+        foreach (var c in compressedBuffer)
         {
-            var result = new List<byte>(compressedBuffer.Length * 2); // Optimized initial capacity
-            var countMode = false;
-            byte last = 0;
-
-            foreach (var c in compressedBuffer)
+            if (!countMode)
             {
-                if (!countMode)
+                if (c == DLE)
                 {
-                    if (c == DLE)
-                    {
-                        countMode = true;
-                    }
-                    else
-                    {
-                        result.Add(c);
-                        last = c;
-                    }
+                    countMode = true;
                 }
                 else
                 {
-                    countMode = false;
-                    if (c == 0)
-                    {
-                        result.Add(DLE);
-                    }
-                    else
-                    {
-                        result.AddRange(Enumerable.Repeat(last, c - 1));
-                    }
+                    result.Add(c);
+                    last = c;
+                }
+            }
+            else
+            {
+                countMode = false;
+                if (c == 0)
+                {
+                    result.Add(DLE);
+                }
+                else
+                {
+                    result.AddRange(Enumerable.Repeat(last, c - 1));
                 }
             }
-            return result;
         }
+        return result;
     }
 }

src/SharpCompress/Compressors/RLE90/RunLength90Stream.cs

@@ -6,91 +6,90 @@ using System.Text;
 using System.Threading.Tasks;
 using SharpCompress.IO;
 
-namespace SharpCompress.Compressors.RLE90
+namespace SharpCompress.Compressors.RLE90;
+
+public class RunLength90Stream : Stream, IStreamStack
 {
-    public class RunLength90Stream : Stream, IStreamStack
+#if DEBUG_STREAMS
+    long IStreamStack.InstanceId { get; set; }
+#endif
+    int IStreamStack.DefaultBufferSize { get; set; }
+
+    Stream IStreamStack.BaseStream() => _stream;
+
+    int IStreamStack.BufferSize
+    {
+        get => 0;
+        set { }
+    }
+    int IStreamStack.BufferPosition
+    {
+        get => 0;
+        set { }
+    }
+
+    void IStreamStack.SetPosition(long position) { }
+
+    private readonly Stream _stream;
+    private const byte DLE = 0x90;
+    private int _compressedSize;
+    private bool _processed = false;
+
+    public RunLength90Stream(Stream stream, int compressedSize)
+    {
+        _stream = stream;
+        _compressedSize = compressedSize;
+#if DEBUG_STREAMS
+        this.DebugConstruct(typeof(RunLength90Stream));
+#endif
+    }
+
+    protected override void Dispose(bool disposing)
     {
 #if DEBUG_STREAMS
-        long IStreamStack.InstanceId { get; set; }
+        this.DebugDispose(typeof(RunLength90Stream));
 #endif
-        int IStreamStack.DefaultBufferSize { get; set; }
-
-        Stream IStreamStack.BaseStream() => _stream;
-
-        int IStreamStack.BufferSize
-        {
-            get => 0;
-            set { }
-        }
-        int IStreamStack.BufferPosition
-        {
-            get => 0;
-            set { }
-        }
-
-        void IStreamStack.SetPosition(long position) { }
-
-        private readonly Stream _stream;
-        private const byte DLE = 0x90;
-        private int _compressedSize;
-        private bool _processed = false;
-
-        public RunLength90Stream(Stream stream, int compressedSize)
-        {
-            _stream = stream;
-            _compressedSize = compressedSize;
-#if DEBUG_STREAMS
-            this.DebugConstruct(typeof(RunLength90Stream));
-#endif
-        }
-
-        protected override void Dispose(bool disposing)
-        {
-#if DEBUG_STREAMS
-            this.DebugDispose(typeof(RunLength90Stream));
-#endif
-            base.Dispose(disposing);
-        }
-
-        public override bool CanRead => true;
-
-        public override bool CanSeek => false;
-
-        public override bool CanWrite => false;
-
-        public override long Length => throw new NotImplementedException();
-
-        public override long Position
-        {
-            get => _stream.Position;
-            set => throw new NotImplementedException();
-        }
-
-        public override void Flush() => throw new NotImplementedException();
-
-        public override int Read(byte[] buffer, int offset, int count)
-        {
-            if (_processed)
-            {
-                return 0;
-            }
-            _processed = true;
-
-            using var binaryReader = new BinaryReader(_stream);
-            byte[] compressedBuffer = binaryReader.ReadBytes(_compressedSize);
-
-            var unpacked = RLE.UnpackRLE(compressedBuffer);
-            unpacked.CopyTo(buffer);
-
-            return unpacked.Count;
-        }
-
-        public override long Seek(long offset, SeekOrigin origin) =>
-            throw new NotImplementedException();
-
-        public override void SetLength(long value) => throw new NotImplementedException();
-
-        public override void Write(byte[] buffer, int offset, int count) =>
-            throw new NotImplementedException();
+        base.Dispose(disposing);
     }
+
+    public override bool CanRead => true;
+
+    public override bool CanSeek => false;
+
+    public override bool CanWrite => false;
+
+    public override long Length => throw new NotImplementedException();
+
+    public override long Position
+    {
+        get => _stream.Position;
+        set => throw new NotImplementedException();
+    }
+
+    public override void Flush() => throw new NotImplementedException();
+
+    public override int Read(byte[] buffer, int offset, int count)
+    {
+        if (_processed)
+        {
+            return 0;
+        }
+        _processed = true;
+
+        using var binaryReader = new BinaryReader(_stream);
+        byte[] compressedBuffer = binaryReader.ReadBytes(_compressedSize);
+
+        var unpacked = RLE.UnpackRLE(compressedBuffer);
+        unpacked.CopyTo(buffer);
+
+        return unpacked.Count;
+    }
+
+    public override long Seek(long offset, SeekOrigin origin) =>
+        throw new NotImplementedException();
+
+    public override void SetLength(long value) => throw new NotImplementedException();
+
+    public override void Write(byte[] buffer, int offset, int count) =>
+        throw new NotImplementedException();
 }

src/SharpCompress/Compressors/Rar/UnpackV1/Unpack.cs

@@ -13,7 +13,7 @@ using SharpCompress.Compressors.Rar.VM;
 
 namespace SharpCompress.Compressors.Rar.UnpackV1;
 
-internal sealed partial class Unpack : BitInput, IRarUnpack
+internal sealed partial class Unpack : BitInput, IRarUnpack, IDisposable
 {
     private readonly BitInput Inp;
     private bool disposed;
@@ -22,17 +22,15 @@ internal sealed partial class Unpack : BitInput, IRarUnpack
         // to ease in porting Unpack50.cs
         Inp = this;
 
-    public override void Dispose()
+    public void Dispose()
     {
         if (!disposed)
         {
-            base.Dispose();
             if (!externalWindow)
             {
                 ArrayPool<byte>.Shared.Return(window);
                 window = null;
             }
-            rarVM.Dispose();
             disposed = true;
         }
     }
@@ -576,111 +574,104 @@ internal sealed partial class Unpack : BitInput, IRarUnpack
 
                     var FilteredDataOffset = Prg.FilteredDataOffset;
                     var FilteredDataSize = Prg.FilteredDataSize;
-                    var FilteredData = ArrayPool<byte>.Shared.Rent(FilteredDataSize);
-                    try
+                    var FilteredData = new byte[FilteredDataSize];
+
+                    for (var i = 0; i < FilteredDataSize; i++)
                     {
-                        Array.Copy(
-                            rarVM.Mem,
-                            FilteredDataOffset,
-                            FilteredData,
-                            0,
-                            FilteredDataSize
-                        );
+                        FilteredData[i] = rarVM.Mem[FilteredDataOffset + i];
 
-                        prgStack[I] = null;
-                        while (I + 1 < prgStack.Count)
+                        // Prg.GlobalData.get(FilteredDataOffset
+                        // +
+                        // i);
+                    }
+
+                    prgStack[I] = null;
+                    while (I + 1 < prgStack.Count)
+                    {
+                        var NextFilter = prgStack[I + 1];
+                        if (
+                            NextFilter is null
+                            || NextFilter.BlockStart != BlockStart
+                            || NextFilter.BlockLength != FilteredDataSize
+                            || NextFilter.NextWindow
+                        )
                         {
-                            var NextFilter = prgStack[I + 1];
-                            if (
-                                NextFilter is null
-                                || NextFilter.BlockStart != BlockStart
-                                || NextFilter.BlockLength != FilteredDataSize
-                                || NextFilter.NextWindow
-                            )
-                            {
-                                break;
-                            }
-
-                            // apply several filters to same data block
-
-                            rarVM.setMemory(0, FilteredData, 0, FilteredDataSize);
-
-                            // .SetMemory(0,FilteredData,FilteredDataSize);
-
-                            var pPrg = filters[NextFilter.ParentFilter].Program;
-                            var NextPrg = NextFilter.Program;
-
-                            if (pPrg.GlobalData.Count > RarVM.VM_FIXEDGLOBALSIZE)
-                            {
-                                // copy global data from previous script execution
-                                // if any
-                                // NextPrg->GlobalData.Alloc(ParentPrg->GlobalData.Size());
-                                NextPrg.GlobalData.SetSize(pPrg.GlobalData.Count);
-
-                                // memcpy(&NextPrg->GlobalData[VM_FIXEDGLOBALSIZE],&ParentPrg->GlobalData[VM_FIXEDGLOBALSIZE],ParentPrg->GlobalData.Size()-VM_FIXEDGLOBALSIZE);
-                                for (
-                                    var i = 0;
-                                    i < pPrg.GlobalData.Count - RarVM.VM_FIXEDGLOBALSIZE;
-                                    i++
-                                )
-                                {
-                                    NextPrg.GlobalData[RarVM.VM_FIXEDGLOBALSIZE + i] =
-                                        pPrg.GlobalData[RarVM.VM_FIXEDGLOBALSIZE + i];
-                                }
-                            }
-
-                            ExecuteCode(NextPrg);
-
-                            if (NextPrg.GlobalData.Count > RarVM.VM_FIXEDGLOBALSIZE)
-                            {
-                                // save global data for next script execution
-                                if (pPrg.GlobalData.Count < NextPrg.GlobalData.Count)
-                                {
-                                    pPrg.GlobalData.SetSize(NextPrg.GlobalData.Count);
-                                }
-
-                                // memcpy(&ParentPrg->GlobalData[VM_FIXEDGLOBALSIZE],&NextPrg->GlobalData[VM_FIXEDGLOBALSIZE],NextPrg->GlobalData.Size()-VM_FIXEDGLOBALSIZE);
-                                for (
-                                    var i = 0;
-                                    i < NextPrg.GlobalData.Count - RarVM.VM_FIXEDGLOBALSIZE;
-                                    i++
-                                )
-                                {
-                                    pPrg.GlobalData[RarVM.VM_FIXEDGLOBALSIZE + i] =
-                                        NextPrg.GlobalData[RarVM.VM_FIXEDGLOBALSIZE + i];
-                                }
-                            }
-                            else
-                            {
-                                pPrg.GlobalData.Clear();
-                            }
-
-                            FilteredDataOffset = NextPrg.FilteredDataOffset;
-                            FilteredDataSize = NextPrg.FilteredDataSize;
-                            if (FilteredData.Length < FilteredDataSize)
-                            {
-                                ArrayPool<byte>.Shared.Return(FilteredData);
-                                FilteredData = ArrayPool<byte>.Shared.Rent(FilteredDataSize);
-                            }
-                            for (var i = 0; i < FilteredDataSize; i++)
-                            {
-                                FilteredData[i] = NextPrg.GlobalData[FilteredDataOffset + i];
-                            }
-
-                            I++;
-                            prgStack[I] = null;
+                            break;
                         }
 
-                        writeStream.Write(FilteredData, 0, FilteredDataSize);
-                        writtenFileSize += FilteredDataSize;
-                        destUnpSize -= FilteredDataSize;
-                        WrittenBorder = BlockEnd;
-                        WriteSize = (unpPtr - WrittenBorder) & PackDef.MAXWINMASK;
-                    }
-                    finally
-                    {
-                        ArrayPool<byte>.Shared.Return(FilteredData);
+                        // apply several filters to same data block
+
+                        rarVM.setMemory(0, FilteredData, 0, FilteredDataSize);
+
+                        // .SetMemory(0,FilteredData,FilteredDataSize);
+
+                        var pPrg = filters[NextFilter.ParentFilter].Program;
+                        var NextPrg = NextFilter.Program;
+
+                        if (pPrg.GlobalData.Count > RarVM.VM_FIXEDGLOBALSIZE)
+                        {
+                            // copy global data from previous script execution
+                            // if any
+                            // NextPrg->GlobalData.Alloc(ParentPrg->GlobalData.Size());
+                            NextPrg.GlobalData.SetSize(pPrg.GlobalData.Count);
+
+                            // memcpy(&NextPrg->GlobalData[VM_FIXEDGLOBALSIZE],&ParentPrg->GlobalData[VM_FIXEDGLOBALSIZE],ParentPrg->GlobalData.Size()-VM_FIXEDGLOBALSIZE);
+                            for (
+                                var i = 0;
+                                i < pPrg.GlobalData.Count - RarVM.VM_FIXEDGLOBALSIZE;
+                                i++
+                            )
+                            {
+                                NextPrg.GlobalData[RarVM.VM_FIXEDGLOBALSIZE + i] = pPrg.GlobalData[
+                                    RarVM.VM_FIXEDGLOBALSIZE + i
+                                ];
+                            }
+                        }
+
+                        ExecuteCode(NextPrg);
+
+                        if (NextPrg.GlobalData.Count > RarVM.VM_FIXEDGLOBALSIZE)
+                        {
+                            // save global data for next script execution
+                            if (pPrg.GlobalData.Count < NextPrg.GlobalData.Count)
+                            {
+                                pPrg.GlobalData.SetSize(NextPrg.GlobalData.Count);
+                            }
+
+                            // memcpy(&ParentPrg->GlobalData[VM_FIXEDGLOBALSIZE],&NextPrg->GlobalData[VM_FIXEDGLOBALSIZE],NextPrg->GlobalData.Size()-VM_FIXEDGLOBALSIZE);
+                            for (
+                                var i = 0;
+                                i < NextPrg.GlobalData.Count - RarVM.VM_FIXEDGLOBALSIZE;
+                                i++
+                            )
+                            {
+                                pPrg.GlobalData[RarVM.VM_FIXEDGLOBALSIZE + i] = NextPrg.GlobalData[
+                                    RarVM.VM_FIXEDGLOBALSIZE + i
+                                ];
+                            }
+                        }
+                        else
+                        {
+                            pPrg.GlobalData.Clear();
+                        }
+                        FilteredDataOffset = NextPrg.FilteredDataOffset;
+                        FilteredDataSize = NextPrg.FilteredDataSize;
+
+                        FilteredData = new byte[FilteredDataSize];
+                        for (var i = 0; i < FilteredDataSize; i++)
+                        {
+                            FilteredData[i] = NextPrg.GlobalData[FilteredDataOffset + i];
+                        }
+
+                        I++;
+                        prgStack[I] = null;
                     }
+                    writeStream.Write(FilteredData, 0, FilteredDataSize);
+                    unpSomeRead = true;
+                    writtenFileSize += FilteredDataSize;
+                    destUnpSize -= FilteredDataSize;
+                    WrittenBorder = BlockEnd;
+                    WriteSize = (unpPtr - WrittenBorder) & PackDef.MAXWINMASK;
                 }
                 else
                 {
@@ -704,10 +695,15 @@ internal sealed partial class Unpack : BitInput, IRarUnpack
 
     private void UnpWriteArea(int startPtr, int endPtr)
     {
+        if (endPtr != startPtr)
+        {
+            unpSomeRead = true;
+        }
         if (endPtr < startPtr)
         {
             UnpWriteData(window, startPtr, -startPtr & PackDef.MAXWINMASK);
             UnpWriteData(window, 0, endPtr);
+            unpAllBuf = true;
         }
         else
         {
@@ -761,27 +757,19 @@ internal sealed partial class Unpack : BitInput, IRarUnpack
         // System.out.println("copyString(" + length + ", " + distance + ")");
 
         var destPtr = unpPtr - distance;
-        var safeZone = PackDef.MAXWINSIZE - 260;
 
-        // Fast path: use Array.Copy for bulk operations when in safe zone
-        if (destPtr >= 0 && destPtr < safeZone && unpPtr < safeZone && distance >= length)
+        // System.out.println(unpPtr+":"+distance);
+        if (destPtr >= 0 && destPtr < PackDef.MAXWINSIZE - 260 && unpPtr < PackDef.MAXWINSIZE - 260)
         {
-            // Non-overlapping copy: can use Array.Copy directly
-            Array.Copy(window, destPtr, window, unpPtr, length);
-            unpPtr += length;
-        }
-        else if (destPtr >= 0 && destPtr < safeZone && unpPtr < safeZone)
-        {
-            // Overlapping copy in safe zone: use byte-by-byte to handle self-referential copies
-            for (int i = 0; i < length; i++)
+            window[unpPtr++] = window[destPtr++];
+
+            while (--length > 0)
             {
-                window[unpPtr + i] = window[destPtr + i];
+                window[unpPtr++] = window[destPtr++];
             }
-            unpPtr += length;
         }
         else
         {
-            // Slow path with wraparound mask
             while (length-- != 0)
             {
                 window[unpPtr] = window[destPtr++ & PackDef.MAXWINMASK];
@@ -1040,7 +1028,7 @@ internal sealed partial class Unpack : BitInput, IRarUnpack
             vmCode.Add((byte)(GetBits() >> 8));
             AddBits(8);
         }
-        return AddVMCode(FirstByte, vmCode);
+        return (AddVMCode(FirstByte, vmCode, Length));
     }
 
     private bool ReadVMCodePPM()
@@ -1085,12 +1073,12 @@ internal sealed partial class Unpack : BitInput, IRarUnpack
             }
             vmCode.Add((byte)Ch); // VMCode[I]=Ch;
         }
-        return AddVMCode(FirstByte, vmCode);
+        return (AddVMCode(FirstByte, vmCode, Length));
     }
 
-    private bool AddVMCode(int firstByte, List<byte> vmCode)
+    private bool AddVMCode(int firstByte, List<byte> vmCode, int length)
     {
-        using var Inp = new BitInput();
+        var Inp = new BitInput();
         Inp.InitBitInput();
 
         // memcpy(Inp.InBuf,Code,Min(BitInput::MAX_SIZE,CodeSize));
@@ -1098,6 +1086,7 @@ internal sealed partial class Unpack : BitInput, IRarUnpack
         {
             Inp.InBuf[i] = vmCode[i];
         }
+        rarVM.init();
 
         int FiltPos;
         if ((firstByte & 0x80) != 0)
@@ -1210,28 +1199,19 @@ internal sealed partial class Unpack : BitInput, IRarUnpack
             {
                 return (false);
             }
-
-            var VMCode = ArrayPool<byte>.Shared.Rent(VMCodeSize);
-            try
+            Span<byte> VMCode = stackalloc byte[VMCodeSize];
+            for (var I = 0; I < VMCodeSize; I++)
             {
-                for (var I = 0; I < VMCodeSize; I++)
+                if (Inp.Overflow(3))
                 {
-                    if (Inp.Overflow(3))
-                    {
-                        return (false);
-                    }
-
-                    VMCode[I] = (byte)(Inp.GetBits() >> 8);
-                    Inp.AddBits(8);
+                    return (false);
                 }
+                VMCode[I] = (byte)(Inp.GetBits() >> 8);
+                Inp.AddBits(8);
+            }
 
-                // VM.Prepare(&VMCode[0],VMCodeSize,&Filter->Prg);
-                rarVM.prepare(VMCode.AsSpan(0, VMCodeSize), Filter.Program);
-            }
-            finally
-            {
-                ArrayPool<byte>.Shared.Return(VMCode);
-            }
+            // VM.Prepare(&VMCode[0],VMCodeSize,&Filter->Prg);
+            rarVM.prepare(VMCode, VMCodeSize, Filter.Program);
         }
         StackFilter.Program.AltCommands = Filter.Program.Commands; // StackFilter->Prg.AltCmd=&Filter->Prg.Cmd[0];
         StackFilter.Program.CommandCount = Filter.Program.CommandCount;

src/SharpCompress/Compressors/Rar/UnpackV1/Unpack15.cs

@@ -19,9 +19,14 @@ internal partial class Unpack
 
     private bool suspended;
 
+    internal bool unpAllBuf;
+
     //private ComprDataIO unpIO;
     private Stream readStream;
     private Stream writeStream;
+
+    internal bool unpSomeRead;
+
     private int readTop;
 
     private long destUnpSize;
@@ -803,10 +808,15 @@ internal partial class Unpack
 
     private void oldUnpWriteBuf()
     {
+        if (unpPtr != wrPtr)
+        {
+            unpSomeRead = true;
+        }
         if (unpPtr < wrPtr)
         {
             writeStream.Write(window, wrPtr, -wrPtr & PackDef.MAXWINMASK);
             writeStream.Write(window, 0, unpPtr);
+            unpAllBuf = true;
         }
         else
         {

src/SharpCompress/Compressors/Rar/UnpackV1/UnpackUtility.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Runtime.CompilerServices;
 using SharpCompress.Compressors.Rar.VM;
 
 namespace SharpCompress.Compressors.Rar.UnpackV1;
@@ -10,15 +9,167 @@ internal static class UnpackUtility
     internal static uint DecodeNumber(this BitInput input, Decode.Decode dec) =>
         (uint)input.decodeNumber(dec);
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
     internal static int decodeNumber(this BitInput input, Decode.Decode dec)
     {
+        int bits;
         long bitField = input.GetBits() & 0xfffe;
+
+        //        if (bitField < dec.getDecodeLen()[8]) {
+        //			if (bitField < dec.getDecodeLen()[4]) {
+        //				if (bitField < dec.getDecodeLen()[2]) {
+        //					if (bitField < dec.getDecodeLen()[1]) {
+        //						bits = 1;
+        //					} else {
+        //						bits = 2;
+        //					}
+        //				} else {
+        //					if (bitField < dec.getDecodeLen()[3]) {
+        //						bits = 3;
+        //					} else {
+        //						bits = 4;
+        //					}
+        //				}
+        //			} else {
+        //				if (bitField < dec.getDecodeLen()[6]) {
+        //					if (bitField < dec.getDecodeLen()[5])
+        //						bits = 5;
+        //					else
+        //						bits = 6;
+        //				} else {
+        //					if (bitField < dec.getDecodeLen()[7]) {
+        //						bits = 7;
+        //					} else {
+        //						bits = 8;
+        //					}
+        //				}
+        //			}
+        //		} else {
+        //			if (bitField < dec.getDecodeLen()[12]) {
+        //				if (bitField < dec.getDecodeLen()[10])
+        //					if (bitField < dec.getDecodeLen()[9])
+        //						bits = 9;
+        //					else
+        //						bits = 10;
+        //				else if (bitField < dec.getDecodeLen()[11])
+        //					bits = 11;
+        //				else
+        //					bits = 12;
+        //			} else {
+        //				if (bitField < dec.getDecodeLen()[14]) {
+        //					if (bitField < dec.getDecodeLen()[13]) {
+        //						bits = 13;
+        //					} else {
+        //						bits = 14;
+        //					}
+        //				} else {
+        //					bits = 15;
+        //				}
+        //			}
+        //		}
+        //		addbits(bits);
+        //		int N = dec.getDecodePos()[bits]
+        //				+ (((int) bitField - dec.getDecodeLen()[bits - 1]) >>> (16 - bits));
+        //		if (N >= dec.getMaxNum()) {
+        //			N = 0;
+        //		}
+        //		return (dec.getDecodeNum()[N]);
         var decodeLen = dec.DecodeLen;
-
-        // Binary search to find the bit length - faster than nested ifs
-        int bits = FindDecodeBits(bitField, decodeLen);
-
+        if (bitField < decodeLen[8])
+        {
+            if (bitField < decodeLen[4])
+            {
+                if (bitField < decodeLen[2])
+                {
+                    if (bitField < decodeLen[1])
+                    {
+                        bits = 1;
+                    }
+                    else
+                    {
+                        bits = 2;
+                    }
+                }
+                else
+                {
+                    if (bitField < decodeLen[3])
+                    {
+                        bits = 3;
+                    }
+                    else
+                    {
+                        bits = 4;
+                    }
+                }
+            }
+            else
+            {
+                if (bitField < decodeLen[6])
+                {
+                    if (bitField < decodeLen[5])
+                    {
+                        bits = 5;
+                    }
+                    else
+                    {
+                        bits = 6;
+                    }
+                }
+                else
+                {
+                    if (bitField < decodeLen[7])
+                    {
+                        bits = 7;
+                    }
+                    else
+                    {
+                        bits = 8;
+                    }
+                }
+            }
+        }
+        else
+        {
+            if (bitField < decodeLen[12])
+            {
+                if (bitField < decodeLen[10])
+                {
+                    if (bitField < decodeLen[9])
+                    {
+                        bits = 9;
+                    }
+                    else
+                    {
+                        bits = 10;
+                    }
+                }
+                else if (bitField < decodeLen[11])
+                {
+                    bits = 11;
+                }
+                else
+                {
+                    bits = 12;
+                }
+            }
+            else
+            {
+                if (bitField < decodeLen[14])
+                {
+                    if (bitField < decodeLen[13])
+                    {
+                        bits = 13;
+                    }
+                    else
+                    {
+                        bits = 14;
+                    }
+                }
+                else
+                {
+                    bits = 15;
+                }
+            }
+        }
         input.AddBits(bits);
         var N =
             dec.DecodePos[bits]
@@ -30,52 +181,6 @@ internal static class UnpackUtility
         return (dec.DecodeNum[N]);
     }
 
-    /// <summary>
-    /// Fast binary search to find which bit length matches the bitField.
-    /// Optimized with cached array access to minimize memory lookups.
-    /// </summary>
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static int FindDecodeBits(long bitField, int[] decodeLen)
-    {
-        // Cache critical values to reduce array access overhead
-        long len4 = decodeLen[4];
-        long len8 = decodeLen[8];
-        long len12 = decodeLen[12];
-
-        if (bitField < len8)
-        {
-            if (bitField < len4)
-            {
-                long len2 = decodeLen[2];
-                if (bitField < len2)
-                {
-                    return bitField < decodeLen[1] ? 1 : 2;
-                }
-                return bitField < decodeLen[3] ? 3 : 4;
-            }
-
-            long len6 = decodeLen[6];
-            if (bitField < len6)
-            {
-                return bitField < decodeLen[5] ? 5 : 6;
-            }
-            return bitField < decodeLen[7] ? 7 : 8;
-        }
-
-        if (bitField < len12)
-        {
-            long len10 = decodeLen[10];
-            if (bitField < len10)
-            {
-                return bitField < decodeLen[9] ? 9 : 10;
-            }
-            return bitField < decodeLen[11] ? 11 : 12;
-        }
-
-        long len14 = decodeLen[14];
-        return bitField < len14 ? (bitField < decodeLen[13] ? 13 : 14) : 15;
-    }
-
     internal static void makeDecodeTables(
         Span<byte> lenTab,
         int offset,
@@ -89,7 +194,8 @@ internal static class UnpackUtility
         long M,
             N;
 
-        new Span<int>(dec.DecodeNum).Clear();
+        new Span<int>(dec.DecodeNum).Clear(); // memset(Dec->DecodeNum,0,Size*sizeof(*Dec->DecodeNum));
+
         for (i = 0; i < size; i++)
         {
             lenCount[lenTab[offset + i] & 0xF]++;

src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.unpack50_cpp.cs

@@ -413,7 +413,7 @@ internal partial class Unpack
                             else
                             //x memcpy(Mem,Window+BlockStart,BlockLength);
                             {
-                                Buffer.BlockCopy(Window, (int)BlockStart, Mem, 0, (int)BlockLength);
+                                Utility.Copy(Window, BlockStart, Mem, 0, BlockLength);
                             }
                         }
                         else
@@ -427,21 +427,9 @@ internal partial class Unpack
                             else
                             {
                                 //x memcpy(Mem,Window+BlockStart,FirstPartLength);
-                                Buffer.BlockCopy(
-                                    Window,
-                                    (int)BlockStart,
-                                    Mem,
-                                    0,
-                                    (int)FirstPartLength
-                                );
+                                Utility.Copy(Window, BlockStart, Mem, 0, FirstPartLength);
                                 //x memcpy(Mem+FirstPartLength,Window,BlockEnd);
-                                Buffer.BlockCopy(
-                                    Window,
-                                    0,
-                                    Mem,
-                                    (int)FirstPartLength,
-                                    (int)BlockEnd
-                                );
+                                Utility.Copy(Window, 0, Mem, FirstPartLength, BlockEnd);
                             }
                         }
 

src/SharpCompress/Compressors/Rar/VM/BitInput.cs

@@ -1,9 +1,6 @@
-using System;
-using System.Buffers;
-
 namespace SharpCompress.Compressors.Rar.VM;
 
-internal class BitInput : IDisposable
+internal class BitInput
 {
     /// <summary> the max size of the input</summary>
     internal const int MAX_SIZE = 0x8000;
@@ -23,11 +20,9 @@ internal class BitInput : IDisposable
         set => inBit = value;
     }
     public bool ExternalBuffer;
-    private byte[] _privateBuffer = ArrayPool<byte>.Shared.Rent(MAX_SIZE);
-    private bool _disposed;
 
     /// <summary>  </summary>
-    internal BitInput() => InBuf = _privateBuffer;
+    internal BitInput() => InBuf = new byte[MAX_SIZE];
 
     internal byte[] InBuf { get; }
 
@@ -92,14 +87,4 @@ internal class BitInput : IDisposable
     /// <returns> true if an Oververflow would occur
     /// </returns>
     internal bool Overflow(int IncPtr) => (inAddr + IncPtr >= MAX_SIZE);
-
-    public virtual void Dispose()
-    {
-        if (_disposed)
-        {
-            return;
-        }
-        ArrayPool<byte>.Shared.Return(_privateBuffer);
-        _disposed = true;
-    }
 }

src/SharpCompress/Compressors/Rar/VM/RarVM.cs

@@ -1,5 +1,6 @@
+#nullable disable
+
 using System;
-using System.Buffers;
 using System.Buffers.Binary;
 using System.Collections.Generic;
 
@@ -15,9 +16,7 @@ internal sealed class RarVM : BitInput
     //    Mem.set_Renamed(offset + 3, Byte.valueOf((sbyte) ((Utility.URShift(value_Renamed, 24)) & 0xff)));
 
     //}
-    internal byte[] Mem => _memory.NotNull();
-
-    private byte[]? _memory = ArrayPool<byte>.Shared.Rent(VM_MEMSIZE + 4);
+    internal byte[] Mem { get; private set; }
 
     public const int VM_MEMSIZE = 0x40000;
 
@@ -41,18 +40,11 @@ internal sealed class RarVM : BitInput
 
     private int IP;
 
-    internal RarVM() { }
+    internal RarVM() =>
+        //InitBlock();
+        Mem = null;
 
-    public override void Dispose()
-    {
-        base.Dispose();
-        if (_memory is null)
-        {
-            return;
-        }
-        ArrayPool<byte>.Shared.Return(_memory);
-        _memory = null;
-    }
+    internal void init() => Mem ??= new byte[VM_MEMSIZE + 4];
 
     private bool IsVMMem(byte[] mem) => Mem == mem;
 
@@ -784,10 +776,9 @@ internal sealed class RarVM : BitInput
         }
     }
 
-    public void prepare(ReadOnlySpan<byte> code, VMPreparedProgram prg)
+    public void prepare(ReadOnlySpan<byte> code, int codeSize, VMPreparedProgram prg)
     {
         InitBitInput();
-        var codeSize = code.Length;
         var cpLength = Math.Min(MAX_SIZE, codeSize);
 
         // memcpy(inBuf,Code,Min(CodeSize,BitInput::MAX_SIZE));
@@ -804,7 +795,7 @@ internal sealed class RarVM : BitInput
         prg.CommandCount = 0;
         if (xorSum == code[0])
         {
-            var filterType = IsStandardFilter(code);
+            var filterType = IsStandardFilter(code, codeSize);
             if (filterType != VMStandardFilters.VMSF_NONE)
             {
                 var curCmd = new VMPreparedCommand();
@@ -1114,7 +1105,7 @@ internal sealed class RarVM : BitInput
         }
     }
 
-    private VMStandardFilters IsStandardFilter(ReadOnlySpan<byte> code)
+    private VMStandardFilters IsStandardFilter(ReadOnlySpan<byte> code, int codeSize)
     {
         VMStandardFilterSignature[] stdList =
         {
@@ -1139,7 +1130,6 @@ internal sealed class RarVM : BitInput
 
     private void ExecuteStandardFilter(VMStandardFilters filterType)
     {
-        var mem = Mem;
         switch (filterType)
         {
             case VMStandardFilters.VMSF_E8:
@@ -1158,7 +1148,7 @@ internal sealed class RarVM : BitInput
                     );
                     for (var curPos = 0; curPos < dataSize - 4; )
                     {
-                        var curByte = mem[curPos++];
+                        var curByte = Mem[curPos++];
                         if (curByte == 0xe8 || curByte == cmpByte2)
                         {
                             //		#ifdef PRESENT_INT32
@@ -1174,19 +1164,19 @@ internal sealed class RarVM : BitInput
                             //		                SET_VALUE(false,Data,Addr-Offset);
                             //		#else
                             var offset = curPos + fileOffset;
-                            long Addr = GetValue(false, mem, curPos);
+                            long Addr = GetValue(false, Mem, curPos);
                             if ((Addr & unchecked((int)0x80000000)) != 0)
                             {
                                 if (((Addr + offset) & unchecked((int)0x80000000)) == 0)
                                 {
-                                    SetValue(false, mem, curPos, (int)Addr + fileSize);
+                                    SetValue(false, Mem, curPos, (int)Addr + fileSize);
                                 }
                             }
                             else
                             {
                                 if (((Addr - fileSize) & unchecked((int)0x80000000)) != 0)
                                 {
-                                    SetValue(false, mem, curPos, (int)(Addr - offset));
+                                    SetValue(false, Mem, curPos, (int)(Addr - offset));
                                 }
                             }
 
@@ -1214,7 +1204,7 @@ internal sealed class RarVM : BitInput
 
                     while (curPos < dataSize - 21)
                     {
-                        var Byte = (mem[curPos] & 0x1f) - 0x10;
+                        var Byte = (Mem[curPos] & 0x1f) - 0x10;
                         if (Byte >= 0)
                         {
                             var cmdMask = Masks[Byte];
@@ -1260,7 +1250,7 @@ internal sealed class RarVM : BitInput
                     var channels = R[0] & unchecked((int)0xFFffFFff);
                     var srcPos = 0;
                     var border = (dataSize * 2) & unchecked((int)0xFFffFFff);
-                    SetValue(false, mem, VM_GLOBALMEMADDR + 0x20, dataSize);
+                    SetValue(false, Mem, VM_GLOBALMEMADDR + 0x20, dataSize);
                     if (dataSize >= VM_GLOBALMEMADDR / 2)
                     {
                         break;
@@ -1278,7 +1268,7 @@ internal sealed class RarVM : BitInput
                             destPos += channels
                         )
                         {
-                            mem[destPos] = (PrevByte = (byte)(PrevByte - mem[srcPos++]));
+                            Mem[destPos] = (PrevByte = (byte)(PrevByte - Mem[srcPos++]));
                         }
                     }
                 }
@@ -1293,7 +1283,7 @@ internal sealed class RarVM : BitInput
                     var channels = 3;
                     var srcPos = 0;
                     var destDataPos = dataSize;
-                    SetValue(false, mem, VM_GLOBALMEMADDR + 0x20, dataSize);
+                    SetValue(false, Mem, VM_GLOBALMEMADDR + 0x20, dataSize);
                     if (dataSize >= VM_GLOBALMEMADDR / 2 || posR < 0)
                     {
                         break;
@@ -1309,8 +1299,8 @@ internal sealed class RarVM : BitInput
                             if (upperPos >= 3)
                             {
                                 var upperDataPos = destDataPos + upperPos;
-                                var upperByte = mem[upperDataPos] & 0xff;
-                                var upperLeftByte = mem[upperDataPos - 3] & 0xff;
+                                var upperByte = Mem[upperDataPos] & 0xff;
+                                var upperLeftByte = Mem[upperDataPos - 3] & 0xff;
                                 predicted = prevByte + upperByte - upperLeftByte;
                                 var pa = Math.Abs((int)(predicted - prevByte));
                                 var pb = Math.Abs((int)(predicted - upperByte));
@@ -1336,15 +1326,15 @@ internal sealed class RarVM : BitInput
                                 predicted = prevByte;
                             }
 
-                            prevByte = ((predicted - mem[srcPos++]) & 0xff) & 0xff;
-                            mem[destDataPos + i] = (byte)(prevByte & 0xff);
+                            prevByte = ((predicted - Mem[srcPos++]) & 0xff) & 0xff;
+                            Mem[destDataPos + i] = (byte)(prevByte & 0xff);
                         }
                     }
                     for (int i = posR, border = dataSize - 2; i < border; i += 3)
                     {
-                        var G = mem[destDataPos + i + 1];
-                        mem[destDataPos + i] = (byte)(mem[destDataPos + i] + G);
-                        mem[destDataPos + i + 2] = (byte)(mem[destDataPos + i + 2] + G);
+                        var G = Mem[destDataPos + i + 1];
+                        Mem[destDataPos + i] = (byte)(Mem[destDataPos + i] + G);
+                        Mem[destDataPos + i + 2] = (byte)(Mem[destDataPos + i + 2] + G);
                     }
                 }
                 break;
@@ -1357,7 +1347,7 @@ internal sealed class RarVM : BitInput
                     var destDataPos = dataSize;
 
                     //byte *SrcData=Mem,*DestData=SrcData+DataSize;
-                    SetValue(false, mem, VM_GLOBALMEMADDR + 0x20, dataSize);
+                    SetValue(false, Mem, VM_GLOBALMEMADDR + 0x20, dataSize);
                     if (dataSize >= VM_GLOBALMEMADDR / 2)
                     {
                         break;
@@ -1387,10 +1377,10 @@ internal sealed class RarVM : BitInput
                             var predicted = (8 * prevByte) + (K1 * D1) + (K2 * D2) + (K3 * D3);
                             predicted = Utility.URShift(predicted, 3) & 0xff;
 
-                            long curByte = mem[srcPos++];
+                            long curByte = Mem[srcPos++];
 
                             predicted -= curByte;
-                            mem[destDataPos + i] = (byte)predicted;
+                            Mem[destDataPos + i] = (byte)predicted;
                             prevDelta = (byte)(predicted - prevByte);
 
                             //fix java byte
@@ -1490,15 +1480,15 @@ internal sealed class RarVM : BitInput
                     }
                     while (srcPos < dataSize)
                     {
-                        var curByte = mem[srcPos++];
-                        if (curByte == 2 && (curByte = mem[srcPos++]) != 2)
+                        var curByte = Mem[srcPos++];
+                        if (curByte == 2 && (curByte = Mem[srcPos++]) != 2)
                         {
                             curByte = (byte)(curByte - 32);
                         }
-                        mem[destPos++] = curByte;
+                        Mem[destPos++] = curByte;
                     }
-                    SetValue(false, mem, VM_GLOBALMEMADDR + 0x1c, destPos - dataSize);
-                    SetValue(false, mem, VM_GLOBALMEMADDR + 0x20, dataSize);
+                    SetValue(false, Mem, VM_GLOBALMEMADDR + 0x1c, destPos - dataSize);
+                    SetValue(false, Mem, VM_GLOBALMEMADDR + 0x20, dataSize);
                 }
                 break;
         }
@@ -1538,14 +1528,15 @@ internal sealed class RarVM : BitInput
     {
         if (pos < VM_MEMSIZE)
         {
-            // Use Array.Copy for fast bulk memory operations instead of byte-by-byte loop
-            // Calculate how much data can actually fit in VM memory
-            int copyLength = Math.Min(dataSize, VM_MEMSIZE - pos);
-            copyLength = Math.Min(copyLength, data.Length - offset);
-
-            if (copyLength > 0)
+            //&& data!=Mem+Pos)
+            //memmove(Mem+Pos,Data,Min(DataSize,VM_MEMSIZE-Pos));
+            for (var i = 0; i < Math.Min(data.Length - offset, dataSize); i++)
             {
-                Array.Copy(data, offset, Mem, pos, copyLength);
+                if ((VM_MEMSIZE - pos) < i)
+                {
+                    break;
+                }
+                Mem[pos + i] = data[offset + i];
             }
         }
     }

src/SharpCompress/Compressors/Shrink/BitStream.cs

@@ -1,79 +1,78 @@
-namespace SharpCompress.Compressors.Shrink
+namespace SharpCompress.Compressors.Shrink;
+
+internal class BitStream
 {
-    internal class BitStream
+    private byte[] _src;
+    private int _srcLen;
+    private int _byteIdx;
+    private int _bitIdx;
+    private int _bitsLeft;
+    private ulong _bitBuffer;
+    private static uint[] _maskBits = new uint[17]
     {
-        private byte[] _src;
-        private int _srcLen;
-        private int _byteIdx;
-        private int _bitIdx;
-        private int _bitsLeft;
-        private ulong _bitBuffer;
-        private static uint[] _maskBits = new uint[17]
-        {
-            0U,
-            1U,
-            3U,
-            7U,
-            15U,
-            31U,
-            63U,
-            (uint)sbyte.MaxValue,
-            (uint)byte.MaxValue,
-            511U,
-            1023U,
-            2047U,
-            4095U,
-            8191U,
-            16383U,
-            (uint)short.MaxValue,
-            (uint)ushort.MaxValue,
-        };
+        0U,
+        1U,
+        3U,
+        7U,
+        15U,
+        31U,
+        63U,
+        (uint)sbyte.MaxValue,
+        (uint)byte.MaxValue,
+        511U,
+        1023U,
+        2047U,
+        4095U,
+        8191U,
+        16383U,
+        (uint)short.MaxValue,
+        (uint)ushort.MaxValue,
+    };
 
-        public BitStream(byte[] src, int srcLen)
+    public BitStream(byte[] src, int srcLen)
+    {
+        _src = src;
+        _srcLen = srcLen;
+        _byteIdx = 0;
+        _bitIdx = 0;
+    }
+
+    public int BytesRead => (_byteIdx << 3) + _bitIdx;
+
+    private int NextByte()
+    {
+        if (_byteIdx >= _srcLen)
         {
-            _src = src;
-            _srcLen = srcLen;
-            _byteIdx = 0;
-            _bitIdx = 0;
+            return 0;
         }
 
-        public int BytesRead => (_byteIdx << 3) + _bitIdx;
+        return _src[_byteIdx++];
+    }
 
-        private int NextByte()
+    public int NextBits(int nbits)
+    {
+        var result = 0;
+        if (nbits > _bitsLeft)
         {
-            if (_byteIdx >= _srcLen)
+            int num;
+            while (_bitsLeft <= 24 && (num = NextByte()) != 1234)
             {
-                return 0;
+                _bitBuffer |= (ulong)num << _bitsLeft;
+                _bitsLeft += 8;
             }
-
-            return _src[_byteIdx++];
         }
+        result = (int)((long)_bitBuffer & (long)_maskBits[nbits]);
+        _bitBuffer >>= nbits;
+        _bitsLeft -= nbits;
+        return result;
+    }
 
-        public int NextBits(int nbits)
+    public bool Advance(int count)
+    {
+        if (_byteIdx > _srcLen)
         {
-            var result = 0;
-            if (nbits > _bitsLeft)
-            {
-                int num;
-                while (_bitsLeft <= 24 && (num = NextByte()) != 1234)
-                {
-                    _bitBuffer |= (ulong)num << _bitsLeft;
-                    _bitsLeft += 8;
-                }
-            }
-            result = (int)((long)_bitBuffer & (long)_maskBits[nbits]);
-            _bitBuffer >>= nbits;
-            _bitsLeft -= nbits;
-            return result;
-        }
-
-        public bool Advance(int count)
-        {
-            if (_byteIdx > _srcLen)
-            {
-                return false;
-            }
-            return true;
+            return false;
         }
+        return true;
     }
 }

src/SharpCompress/Compressors/Shrink/HwUnshrink.cs

@@ -1,275 +1,297 @@
 using System;
 
-namespace SharpCompress.Compressors.Shrink
+namespace SharpCompress.Compressors.Shrink;
+
+public class HwUnshrink
 {
-    public class HwUnshrink
+    private const int MIN_CODE_SIZE = 9;
+    private const int MAX_CODE_SIZE = 13;
+
+    private const ushort MAX_CODE = (ushort)((1U << MAX_CODE_SIZE) - 1);
+    private const ushort INVALID_CODE = ushort.MaxValue;
+    private const ushort CONTROL_CODE = 256;
+    private const ushort INC_CODE_SIZE = 1;
+    private const ushort PARTIAL_CLEAR = 2;
+
+    private const int HASH_BITS = MAX_CODE_SIZE + 1; // For a load factor of 0.5.
+    private const int HASHTAB_SIZE = 1 << HASH_BITS;
+    private const ushort UNKNOWN_LEN = ushort.MaxValue;
+
+    private struct CodeTabEntry
     {
-        private const int MIN_CODE_SIZE = 9;
-        private const int MAX_CODE_SIZE = 13;
+        public int prefixCode; // INVALID_CODE means the entry is invalid.
+        public byte extByte;
+        public ushort len;
+        public int lastDstPos;
+    }
 
-        private const ushort MAX_CODE = (ushort)((1U << MAX_CODE_SIZE) - 1);
-        private const ushort INVALID_CODE = ushort.MaxValue;
-        private const ushort CONTROL_CODE = 256;
-        private const ushort INC_CODE_SIZE = 1;
-        private const ushort PARTIAL_CLEAR = 2;
-
-        private const int HASH_BITS = MAX_CODE_SIZE + 1; // For a load factor of 0.5.
-        private const int HASHTAB_SIZE = 1 << HASH_BITS;
-        private const ushort UNKNOWN_LEN = ushort.MaxValue;
-
-        private struct CodeTabEntry
+    private static void CodeTabInit(CodeTabEntry[] codeTab)
+    {
+        for (var i = 0; i <= byte.MaxValue; i++)
         {
-            public int prefixCode; // INVALID_CODE means the entry is invalid.
-            public byte extByte;
-            public ushort len;
-            public int lastDstPos;
+            codeTab[i].prefixCode = (ushort)i;
+            codeTab[i].extByte = (byte)i;
+            codeTab[i].len = 1;
         }
 
-        private static void CodeTabInit(CodeTabEntry[] codeTab)
+        for (var i = byte.MaxValue + 1; i <= MAX_CODE; i++)
         {
-            for (var i = 0; i <= byte.MaxValue; i++)
-            {
-                codeTab[i].prefixCode = (ushort)i;
-                codeTab[i].extByte = (byte)i;
-                codeTab[i].len = 1;
-            }
+            codeTab[i].prefixCode = INVALID_CODE;
+        }
+    }
 
-            for (var i = byte.MaxValue + 1; i <= MAX_CODE; i++)
+    private static void UnshrinkPartialClear(CodeTabEntry[] codeTab, ref CodeQueue queue)
+    {
+        var isPrefix = new bool[MAX_CODE + 1];
+        int codeQueueSize;
+
+        // Scan for codes that have been used as a prefix.
+        for (var i = CONTROL_CODE + 1; i <= MAX_CODE; i++)
+        {
+            if (codeTab[i].prefixCode != INVALID_CODE)
+            {
+                isPrefix[codeTab[i].prefixCode] = true;
+            }
+        }
+
+        // Clear "non-prefix" codes in the table; populate the code queue.
+        codeQueueSize = 0;
+        for (var i = CONTROL_CODE + 1; i <= MAX_CODE; i++)
+        {
+            if (!isPrefix[i])
             {
                 codeTab[i].prefixCode = INVALID_CODE;
+                queue.codes[codeQueueSize++] = (ushort)i;
             }
         }
 
-        private static void UnshrinkPartialClear(CodeTabEntry[] codeTab, ref CodeQueue queue)
+        queue.codes[codeQueueSize] = INVALID_CODE; // End-of-queue marker.
+        queue.nextIdx = 0;
+    }
+
+    private static bool ReadCode(
+        BitStream stream,
+        ref int codeSize,
+        CodeTabEntry[] codeTab,
+        ref CodeQueue queue,
+        out int nextCode
+    )
+    {
+        int code,
+            controlCode;
+
+        code = (int)stream.NextBits(codeSize);
+        if (!stream.Advance(codeSize))
         {
-            var isPrefix = new bool[MAX_CODE + 1];
-            int codeQueueSize;
-
-            // Scan for codes that have been used as a prefix.
-            for (var i = CONTROL_CODE + 1; i <= MAX_CODE; i++)
-            {
-                if (codeTab[i].prefixCode != INVALID_CODE)
-                {
-                    isPrefix[codeTab[i].prefixCode] = true;
-                }
-            }
-
-            // Clear "non-prefix" codes in the table; populate the code queue.
-            codeQueueSize = 0;
-            for (var i = CONTROL_CODE + 1; i <= MAX_CODE; i++)
-            {
-                if (!isPrefix[i])
-                {
-                    codeTab[i].prefixCode = INVALID_CODE;
-                    queue.codes[codeQueueSize++] = (ushort)i;
-                }
-            }
-
-            queue.codes[codeQueueSize] = INVALID_CODE; // End-of-queue marker.
-            queue.nextIdx = 0;
+            nextCode = INVALID_CODE;
+            return false;
         }
 
-        private static bool ReadCode(
-            BitStream stream,
-            ref int codeSize,
-            CodeTabEntry[] codeTab,
-            ref CodeQueue queue,
-            out int nextCode
-        )
+        // Handle regular codes (the common case).
+        if (code != CONTROL_CODE)
         {
-            int code,
-                controlCode;
-
-            code = (int)stream.NextBits(codeSize);
-            if (!stream.Advance(codeSize))
-            {
-                nextCode = INVALID_CODE;
-                return false;
-            }
-
-            // Handle regular codes (the common case).
-            if (code != CONTROL_CODE)
-            {
-                nextCode = code;
-                return true;
-            }
-
-            // Handle control codes.
-            controlCode = (ushort)stream.NextBits(codeSize);
-            if (!stream.Advance(codeSize))
-            {
-                nextCode = INVALID_CODE;
-                return true;
-            }
-
-            if (controlCode == INC_CODE_SIZE && codeSize < MAX_CODE_SIZE)
-            {
-                codeSize++;
-                return ReadCode(stream, ref codeSize, codeTab, ref queue, out nextCode);
-            }
-
-            if (controlCode == PARTIAL_CLEAR)
-            {
-                UnshrinkPartialClear(codeTab, ref queue);
-                return ReadCode(stream, ref codeSize, codeTab, ref queue, out nextCode);
-            }
+            nextCode = code;
+            return true;
+        }
 
+        // Handle control codes.
+        controlCode = (ushort)stream.NextBits(codeSize);
+        if (!stream.Advance(codeSize))
+        {
             nextCode = INVALID_CODE;
             return true;
         }
 
-        private static void CopyFromPrevPos(byte[] dst, int prevPos, int dstPos, int len)
+        if (controlCode == INC_CODE_SIZE && codeSize < MAX_CODE_SIZE)
         {
-            if (dstPos + len > dst.Length)
-            {
-                // Not enough room in dst for the sloppy copy below.
-                Array.Copy(dst, prevPos, dst, dstPos, len);
-                return;
-            }
-
-            if (prevPos + len > dstPos)
-            {
-                // Benign one-byte overlap possible in the KwKwK case.
-                //assert(prevPos + len == dstPos + 1);
-                //assert(dst[prevPos] == dst[prevPos + len - 1]);
-            }
-
-            Buffer.BlockCopy(dst, prevPos, dst, dstPos, len);
+            codeSize++;
+            return ReadCode(stream, ref codeSize, codeTab, ref queue, out nextCode);
         }
 
-        private static UnshrnkStatus OutputCode(
-            int code,
-            byte[] dst,
-            int dstPos,
-            int dstCap,
-            int prevCode,
-            CodeTabEntry[] codeTab,
-            ref CodeQueue queue,
-            out byte firstByte,
-            out int len
-        )
+        if (controlCode == PARTIAL_CLEAR)
         {
-            int prefixCode;
+            UnshrinkPartialClear(codeTab, ref queue);
+            return ReadCode(stream, ref codeSize, codeTab, ref queue, out nextCode);
+        }
 
-            //assert(code <= MAX_CODE && code != CONTROL_CODE);
-            //assert(dstPos < dstCap);
+        nextCode = INVALID_CODE;
+        return true;
+    }
+
+    private static void CopyFromPrevPos(byte[] dst, int prevPos, int dstPos, int len)
+    {
+        if (dstPos + len > dst.Length)
+        {
+            // Not enough room in dst for the sloppy copy below.
+            Array.Copy(dst, prevPos, dst, dstPos, len);
+            return;
+        }
+
+        if (prevPos + len > dstPos)
+        {
+            // Benign one-byte overlap possible in the KwKwK case.
+            //assert(prevPos + len == dstPos + 1);
+            //assert(dst[prevPos] == dst[prevPos + len - 1]);
+        }
+
+        Buffer.BlockCopy(dst, prevPos, dst, dstPos, len);
+    }
+
+    private static UnshrnkStatus OutputCode(
+        int code,
+        byte[] dst,
+        int dstPos,
+        int dstCap,
+        int prevCode,
+        CodeTabEntry[] codeTab,
+        ref CodeQueue queue,
+        out byte firstByte,
+        out int len
+    )
+    {
+        int prefixCode;
+
+        //assert(code <= MAX_CODE && code != CONTROL_CODE);
+        //assert(dstPos < dstCap);
+        firstByte = 0;
+        if (code <= byte.MaxValue)
+        {
+            // Output literal byte.
+            firstByte = (byte)code;
+            len = 1;
+            dst[dstPos] = (byte)code;
+            return UnshrnkStatus.Ok;
+        }
+
+        if (codeTab[code].prefixCode == INVALID_CODE || codeTab[code].prefixCode == code)
+        {
+            // Reject invalid codes. Self-referential codes may exist in the table but cannot be used.
             firstByte = 0;
-            if (code <= byte.MaxValue)
-            {
-                // Output literal byte.
-                firstByte = (byte)code;
-                len = 1;
-                dst[dstPos] = (byte)code;
-                return UnshrnkStatus.Ok;
-            }
+            len = 0;
+            return UnshrnkStatus.Error;
+        }
 
-            if (codeTab[code].prefixCode == INVALID_CODE || codeTab[code].prefixCode == code)
-            {
-                // Reject invalid codes. Self-referential codes may exist in the table but cannot be used.
-                firstByte = 0;
-                len = 0;
-                return UnshrnkStatus.Error;
-            }
-
-            if (codeTab[code].len != UNKNOWN_LEN)
-            {
-                // Output string with known length (the common case).
-                if (dstCap - dstPos < codeTab[code].len)
-                {
-                    firstByte = 0;
-                    len = 0;
-                    return UnshrnkStatus.Full;
-                }
-
-                CopyFromPrevPos(dst, codeTab[code].lastDstPos, dstPos, codeTab[code].len);
-                firstByte = dst[dstPos];
-                len = codeTab[code].len;
-                return UnshrnkStatus.Ok;
-            }
-
-            // Output a string of unknown length.
-            //assert(codeTab[code].len == UNKNOWN_LEN);
-            prefixCode = codeTab[code].prefixCode;
-            // assert(prefixCode > CONTROL_CODE);
-
-            if (prefixCode == queue.codes[queue.nextIdx])
-            {
-                // The prefix code hasn't been added yet, but we were just about to: the KwKwK case.
-                //assert(codeTab[prevCode].prefixCode != INVALID_CODE);
-                codeTab[prefixCode].prefixCode = prevCode;
-                codeTab[prefixCode].extByte = firstByte;
-                codeTab[prefixCode].len = (ushort)(codeTab[prevCode].len + 1);
-                codeTab[prefixCode].lastDstPos = codeTab[prevCode].lastDstPos;
-                dst[dstPos] = firstByte;
-            }
-            else if (codeTab[prefixCode].prefixCode == INVALID_CODE)
-            {
-                // The prefix code is still invalid.
-                firstByte = 0;
-                len = 0;
-                return UnshrnkStatus.Error;
-            }
-
-            // Output the prefix string, then the extension byte.
-            len = codeTab[prefixCode].len + 1;
-            if (dstCap - dstPos < len)
+        if (codeTab[code].len != UNKNOWN_LEN)
+        {
+            // Output string with known length (the common case).
+            if (dstCap - dstPos < codeTab[code].len)
             {
                 firstByte = 0;
                 len = 0;
                 return UnshrnkStatus.Full;
             }
 
-            CopyFromPrevPos(dst, codeTab[prefixCode].lastDstPos, dstPos, codeTab[prefixCode].len);
-            dst[dstPos + len - 1] = codeTab[code].extByte;
+            CopyFromPrevPos(dst, codeTab[code].lastDstPos, dstPos, codeTab[code].len);
             firstByte = dst[dstPos];
-
-            // Update the code table now that the string has a length and pos.
-            //assert(prevCode != code);
-            codeTab[code].len = (ushort)len;
-            codeTab[code].lastDstPos = dstPos;
-
+            len = codeTab[code].len;
             return UnshrnkStatus.Ok;
         }
 
-        public static UnshrnkStatus Unshrink(
-            byte[] src,
-            int srcLen,
-            out int srcUsed,
-            byte[] dst,
-            int dstCap,
-            out int dstUsed
-        )
+        // Output a string of unknown length.
+        //assert(codeTab[code].len == UNKNOWN_LEN);
+        prefixCode = codeTab[code].prefixCode;
+        // assert(prefixCode > CONTROL_CODE);
+
+        if (prefixCode == queue.codes[queue.nextIdx])
         {
-            var codeTab = new CodeTabEntry[HASHTAB_SIZE];
-            var queue = new CodeQueue();
-            var stream = new BitStream(src, srcLen);
-            int codeSize,
-                dstPos,
-                len;
-            int currCode,
-                prevCode,
-                newCode;
-            byte firstByte;
+            // The prefix code hasn't been added yet, but we were just about to: the KwKwK case.
+            //assert(codeTab[prevCode].prefixCode != INVALID_CODE);
+            codeTab[prefixCode].prefixCode = prevCode;
+            codeTab[prefixCode].extByte = firstByte;
+            codeTab[prefixCode].len = (ushort)(codeTab[prevCode].len + 1);
+            codeTab[prefixCode].lastDstPos = codeTab[prevCode].lastDstPos;
+            dst[dstPos] = firstByte;
+        }
+        else if (codeTab[prefixCode].prefixCode == INVALID_CODE)
+        {
+            // The prefix code is still invalid.
+            firstByte = 0;
+            len = 0;
+            return UnshrnkStatus.Error;
+        }
 
-            CodeTabInit(codeTab);
-            CodeQueueInit(ref queue);
-            codeSize = MIN_CODE_SIZE;
-            dstPos = 0;
+        // Output the prefix string, then the extension byte.
+        len = codeTab[prefixCode].len + 1;
+        if (dstCap - dstPos < len)
+        {
+            firstByte = 0;
+            len = 0;
+            return UnshrnkStatus.Full;
+        }
 
-            // Handle the first code separately since there is no previous code.
-            if (!ReadCode(stream, ref codeSize, codeTab, ref queue, out currCode))
+        CopyFromPrevPos(dst, codeTab[prefixCode].lastDstPos, dstPos, codeTab[prefixCode].len);
+        dst[dstPos + len - 1] = codeTab[code].extByte;
+        firstByte = dst[dstPos];
+
+        // Update the code table now that the string has a length and pos.
+        //assert(prevCode != code);
+        codeTab[code].len = (ushort)len;
+        codeTab[code].lastDstPos = dstPos;
+
+        return UnshrnkStatus.Ok;
+    }
+
+    public static UnshrnkStatus Unshrink(
+        byte[] src,
+        int srcLen,
+        out int srcUsed,
+        byte[] dst,
+        int dstCap,
+        out int dstUsed
+    )
+    {
+        var codeTab = new CodeTabEntry[HASHTAB_SIZE];
+        var queue = new CodeQueue();
+        var stream = new BitStream(src, srcLen);
+        int codeSize,
+            dstPos,
+            len;
+        int currCode,
+            prevCode,
+            newCode;
+        byte firstByte;
+
+        CodeTabInit(codeTab);
+        CodeQueueInit(ref queue);
+        codeSize = MIN_CODE_SIZE;
+        dstPos = 0;
+
+        // Handle the first code separately since there is no previous code.
+        if (!ReadCode(stream, ref codeSize, codeTab, ref queue, out currCode))
+        {
+            srcUsed = stream.BytesRead;
+            dstUsed = 0;
+            return UnshrnkStatus.Ok;
+        }
+
+        //assert(currCode != CONTROL_CODE);
+        if (currCode > byte.MaxValue)
+        {
+            srcUsed = stream.BytesRead;
+            dstUsed = 0;
+            return UnshrnkStatus.Error; // The first code must be a literal.
+        }
+
+        if (dstPos == dstCap)
+        {
+            srcUsed = stream.BytesRead;
+            dstUsed = 0;
+            return UnshrnkStatus.Full;
+        }
+
+        firstByte = (byte)currCode;
+        dst[dstPos] = (byte)currCode;
+        codeTab[currCode].lastDstPos = dstPos;
+        dstPos++;
+
+        prevCode = currCode;
+        while (ReadCode(stream, ref codeSize, codeTab, ref queue, out currCode))
+        {
+            if (currCode == INVALID_CODE)
             {
                 srcUsed = stream.BytesRead;
                 dstUsed = 0;
-                return UnshrnkStatus.Ok;
-            }
-
-            //assert(currCode != CONTROL_CODE);
-            if (currCode > byte.MaxValue)
-            {
-                srcUsed = stream.BytesRead;
-                dstUsed = 0;
-                return UnshrnkStatus.Error; // The first code must be a literal.
+                return UnshrnkStatus.Error;
             }
 
             if (dstPos == dstCap)
@@ -279,153 +301,130 @@ namespace SharpCompress.Compressors.Shrink
                 return UnshrnkStatus.Full;
             }
 
-            firstByte = (byte)currCode;
-            dst[dstPos] = (byte)currCode;
-            codeTab[currCode].lastDstPos = dstPos;
-            dstPos++;
-
-            prevCode = currCode;
-            while (ReadCode(stream, ref codeSize, codeTab, ref queue, out currCode))
+            // Handle KwKwK: next code used before being added.
+            if (currCode == queue.codes[queue.nextIdx])
             {
-                if (currCode == INVALID_CODE)
+                if (codeTab[prevCode].prefixCode == INVALID_CODE)
                 {
+                    // The previous code is no longer valid.
                     srcUsed = stream.BytesRead;
                     dstUsed = 0;
                     return UnshrnkStatus.Error;
                 }
 
-                if (dstPos == dstCap)
-                {
-                    srcUsed = stream.BytesRead;
-                    dstUsed = 0;
-                    return UnshrnkStatus.Full;
-                }
-
-                // Handle KwKwK: next code used before being added.
-                if (currCode == queue.codes[queue.nextIdx])
-                {
-                    if (codeTab[prevCode].prefixCode == INVALID_CODE)
-                    {
-                        // The previous code is no longer valid.
-                        srcUsed = stream.BytesRead;
-                        dstUsed = 0;
-                        return UnshrnkStatus.Error;
-                    }
-
-                    // Extend the previous code with its first byte.
-                    //assert(currCode != prevCode);
-                    codeTab[currCode].prefixCode = prevCode;
-                    codeTab[currCode].extByte = firstByte;
-                    codeTab[currCode].len = (ushort)(codeTab[prevCode].len + 1);
-                    codeTab[currCode].lastDstPos = codeTab[prevCode].lastDstPos;
-                    //assert(dstPos < dstCap);
-                    dst[dstPos] = firstByte;
-                }
-
-                // Output the string represented by the current code.
-                var status = OutputCode(
-                    currCode,
-                    dst,
-                    dstPos,
-                    dstCap,
-                    prevCode,
-                    codeTab,
-                    ref queue,
-                    out firstByte,
-                    out len
-                );
-                if (status != UnshrnkStatus.Ok)
-                {
-                    srcUsed = stream.BytesRead;
-                    dstUsed = 0;
-                    return status;
-                }
-
-                // Verify that the output matches walking the prefixes.
-                var c = currCode;
-                for (var i = 0; i < len; i++)
-                {
-                    // assert(codeTab[c].len == len - i);
-                    //assert(codeTab[c].extByte == dst[dstPos + len - i - 1]);
-                    c = codeTab[c].prefixCode;
-                }
-
-                // Add a new code to the string table if there's room.
-                // The string is the previous code's string extended with the first byte of the current code's string.
-                newCode = CodeQueueRemoveNext(ref queue);
-                if (newCode != INVALID_CODE)
-                {
-                    //assert(codeTab[prevCode].lastDstPos < dstPos);
-                    codeTab[newCode].prefixCode = prevCode;
-                    codeTab[newCode].extByte = firstByte;
-                    codeTab[newCode].len = (ushort)(codeTab[prevCode].len + 1);
-                    codeTab[newCode].lastDstPos = codeTab[prevCode].lastDstPos;
-
-                    if (codeTab[prevCode].prefixCode == INVALID_CODE)
-                    {
-                        // prevCode was invalidated in a partial clearing. Until that code is re-used, the
-                        // string represented by newCode is indeterminate.
-                        codeTab[newCode].len = UNKNOWN_LEN;
-                    }
-                    // If prevCode was invalidated in a partial clearing, it's possible that newCode == prevCode,
-                    // in which case it will never be used or cleared.
-                }
-
-                codeTab[currCode].lastDstPos = dstPos;
-                dstPos += len;
-
-                prevCode = currCode;
+                // Extend the previous code with its first byte.
+                //assert(currCode != prevCode);
+                codeTab[currCode].prefixCode = prevCode;
+                codeTab[currCode].extByte = firstByte;
+                codeTab[currCode].len = (ushort)(codeTab[prevCode].len + 1);
+                codeTab[currCode].lastDstPos = codeTab[prevCode].lastDstPos;
+                //assert(dstPos < dstCap);
+                dst[dstPos] = firstByte;
             }
 
-            srcUsed = stream.BytesRead;
-            dstUsed = dstPos;
-
-            return UnshrnkStatus.Ok;
-        }
-
-        public enum UnshrnkStatus
-        {
-            Ok,
-            Full,
-            Error,
-        }
-
-        private struct CodeQueue
-        {
-            public int nextIdx;
-            public ushort[] codes;
-        }
-
-        private static void CodeQueueInit(ref CodeQueue q)
-        {
-            int codeQueueSize;
-            ushort code;
-
-            codeQueueSize = 0;
-            q.codes = new ushort[MAX_CODE - CONTROL_CODE + 2];
-
-            for (code = CONTROL_CODE + 1; code <= MAX_CODE; code++)
+            // Output the string represented by the current code.
+            var status = OutputCode(
+                currCode,
+                dst,
+                dstPos,
+                dstCap,
+                prevCode,
+                codeTab,
+                ref queue,
+                out firstByte,
+                out len
+            );
+            if (status != UnshrnkStatus.Ok)
             {
-                q.codes[codeQueueSize++] = code;
+                srcUsed = stream.BytesRead;
+                dstUsed = 0;
+                return status;
             }
 
-            //assert(codeQueueSize < q.codes.Length);
-            q.codes[codeQueueSize] = INVALID_CODE; // End-of-queue marker.
-            q.nextIdx = 0;
-        }
-
-        private static ushort CodeQueueNext(ref CodeQueue q) =>
-            //assert(q.nextIdx < q.codes.Length);
-            q.codes[q.nextIdx];
-
-        private static ushort CodeQueueRemoveNext(ref CodeQueue q)
-        {
-            var code = CodeQueueNext(ref q);
-            if (code != INVALID_CODE)
+            // Verify that the output matches walking the prefixes.
+            var c = currCode;
+            for (var i = 0; i < len; i++)
             {
-                q.nextIdx++;
+                // assert(codeTab[c].len == len - i);
+                //assert(codeTab[c].extByte == dst[dstPos + len - i - 1]);
+                c = codeTab[c].prefixCode;
             }
-            return code;
+
+            // Add a new code to the string table if there's room.
+            // The string is the previous code's string extended with the first byte of the current code's string.
+            newCode = CodeQueueRemoveNext(ref queue);
+            if (newCode != INVALID_CODE)
+            {
+                //assert(codeTab[prevCode].lastDstPos < dstPos);
+                codeTab[newCode].prefixCode = prevCode;
+                codeTab[newCode].extByte = firstByte;
+                codeTab[newCode].len = (ushort)(codeTab[prevCode].len + 1);
+                codeTab[newCode].lastDstPos = codeTab[prevCode].lastDstPos;
+
+                if (codeTab[prevCode].prefixCode == INVALID_CODE)
+                {
+                    // prevCode was invalidated in a partial clearing. Until that code is re-used, the
+                    // string represented by newCode is indeterminate.
+                    codeTab[newCode].len = UNKNOWN_LEN;
+                }
+                // If prevCode was invalidated in a partial clearing, it's possible that newCode == prevCode,
+                // in which case it will never be used or cleared.
+            }
+
+            codeTab[currCode].lastDstPos = dstPos;
+            dstPos += len;
+
+            prevCode = currCode;
         }
+
+        srcUsed = stream.BytesRead;
+        dstUsed = dstPos;
+
+        return UnshrnkStatus.Ok;
+    }
+
+    public enum UnshrnkStatus
+    {
+        Ok,
+        Full,
+        Error,
+    }
+
+    private struct CodeQueue
+    {
+        public int nextIdx;
+        public ushort[] codes;
+    }
+
+    private static void CodeQueueInit(ref CodeQueue q)
+    {
+        int codeQueueSize;
+        ushort code;
+
+        codeQueueSize = 0;
+        q.codes = new ushort[MAX_CODE - CONTROL_CODE + 2];
+
+        for (code = CONTROL_CODE + 1; code <= MAX_CODE; code++)
+        {
+            q.codes[codeQueueSize++] = code;
+        }
+
+        //assert(codeQueueSize < q.codes.Length);
+        q.codes[codeQueueSize] = INVALID_CODE; // End-of-queue marker.
+        q.nextIdx = 0;
+    }
+
+    private static ushort CodeQueueNext(ref CodeQueue q) =>
+        //assert(q.nextIdx < q.codes.Length);
+        q.codes[q.nextIdx];
+
+    private static ushort CodeQueueRemoveNext(ref CodeQueue q)
+    {
+        var code = CodeQueueNext(ref q);
+        if (code != INVALID_CODE)
+        {
+            q.nextIdx++;
+        }
+        return code;
     }
 }

src/SharpCompress/Compressors/Squeezed/SqueezedStream.cs

@@ -7,139 +7,138 @@ using System.Threading.Tasks;
 using SharpCompress.Compressors.RLE90;
 using SharpCompress.IO;
 
-namespace SharpCompress.Compressors.Squeezed
+namespace SharpCompress.Compressors.Squeezed;
+
+public class SqueezeStream : Stream, IStreamStack
 {
-    public class SqueezeStream : Stream, IStreamStack
+#if DEBUG_STREAMS
+    long IStreamStack.InstanceId { get; set; }
+#endif
+    int IStreamStack.DefaultBufferSize { get; set; }
+
+    Stream IStreamStack.BaseStream() => _stream;
+
+    int IStreamStack.BufferSize
+    {
+        get => 0;
+        set { }
+    }
+    int IStreamStack.BufferPosition
+    {
+        get => 0;
+        set { }
+    }
+
+    void IStreamStack.SetPosition(long position) { }
+
+    private readonly Stream _stream;
+    private readonly int _compressedSize;
+    private const int NUMVALS = 257;
+    private const int SPEOF = 256;
+    private bool _processed = false;
+
+    public SqueezeStream(Stream stream, int compressedSize)
+    {
+        _stream = stream;
+        _compressedSize = compressedSize;
+#if DEBUG_STREAMS
+        this.DebugConstruct(typeof(SqueezeStream));
+#endif
+    }
+
+    protected override void Dispose(bool disposing)
     {
 #if DEBUG_STREAMS
-        long IStreamStack.InstanceId { get; set; }
+        this.DebugDispose(typeof(SqueezeStream));
 #endif
-        int IStreamStack.DefaultBufferSize { get; set; }
+        base.Dispose(disposing);
+    }
 
-        Stream IStreamStack.BaseStream() => _stream;
+    public override bool CanRead => true;
 
-        int IStreamStack.BufferSize
+    public override bool CanSeek => false;
+
+    public override bool CanWrite => false;
+
+    public override long Length => throw new NotImplementedException();
+
+    public override long Position
+    {
+        get => _stream.Position;
+        set => throw new NotImplementedException();
+    }
+
+    public override void Flush() => throw new NotImplementedException();
+
+    public override int Read(byte[] buffer, int offset, int count)
+    {
+        if (_processed)
         {
-            get => 0;
-            set { }
+            return 0;
         }
-        int IStreamStack.BufferPosition
+        _processed = true;
+        using var binaryReader = new BinaryReader(_stream);
+
+        // Read numnodes (equivalent to convert_u16!(numnodes, buf))
+        var numnodes = binaryReader.ReadUInt16();
+
+        // Validation: numnodes should be within bounds
+        if (numnodes >= NUMVALS)
         {
-            get => 0;
-            set { }
+            throw new InvalidDataException(
+                $"Invalid number of nodes {numnodes} (max {NUMVALS - 1})"
+            );
         }
 
-        void IStreamStack.SetPosition(long position) { }
-
-        private readonly Stream _stream;
-        private readonly int _compressedSize;
-        private const int NUMVALS = 257;
-        private const int SPEOF = 256;
-        private bool _processed = false;
-
-        public SqueezeStream(Stream stream, int compressedSize)
+        // Handle the case where no nodes exist
+        if (numnodes == 0)
         {
-            _stream = stream;
-            _compressedSize = compressedSize;
-#if DEBUG_STREAMS
-            this.DebugConstruct(typeof(SqueezeStream));
-#endif
+            return 0;
         }
 
-        protected override void Dispose(bool disposing)
+        // Build dnode (tree of nodes)
+        var dnode = new int[numnodes, 2];
+        for (int j = 0; j < numnodes; j++)
         {
-#if DEBUG_STREAMS
-            this.DebugDispose(typeof(SqueezeStream));
-#endif
-            base.Dispose(disposing);
+            dnode[j, 0] = binaryReader.ReadInt16();
+            dnode[j, 1] = binaryReader.ReadInt16();
         }
 
-        public override bool CanRead => true;
+        // Initialize BitReader for reading bits
+        var bitReader = new BitReader(_stream);
+        var decoded = new List<byte>();
 
-        public override bool CanSeek => false;
-
-        public override bool CanWrite => false;
-
-        public override long Length => throw new NotImplementedException();
-
-        public override long Position
+        int i = 0;
+        // Decode the buffer using the dnode tree
+        while (true)
         {
-            get => _stream.Position;
-            set => throw new NotImplementedException();
-        }
-
-        public override void Flush() => throw new NotImplementedException();
-
-        public override int Read(byte[] buffer, int offset, int count)
-        {
-            if (_processed)
+            i = dnode[i, bitReader.ReadBit() ? 1 : 0];
+            if (i < 0)
             {
-                return 0;
-            }
-            _processed = true;
-            using var binaryReader = new BinaryReader(_stream);
-
-            // Read numnodes (equivalent to convert_u16!(numnodes, buf))
-            var numnodes = binaryReader.ReadUInt16();
-
-            // Validation: numnodes should be within bounds
-            if (numnodes >= NUMVALS)
-            {
-                throw new InvalidDataException(
-                    $"Invalid number of nodes {numnodes} (max {NUMVALS - 1})"
-                );
-            }
-
-            // Handle the case where no nodes exist
-            if (numnodes == 0)
-            {
-                return 0;
-            }
-
-            // Build dnode (tree of nodes)
-            var dnode = new int[numnodes, 2];
-            for (int j = 0; j < numnodes; j++)
-            {
-                dnode[j, 0] = binaryReader.ReadInt16();
-                dnode[j, 1] = binaryReader.ReadInt16();
-            }
-
-            // Initialize BitReader for reading bits
-            var bitReader = new BitReader(_stream);
-            var decoded = new List<byte>();
-
-            int i = 0;
-            // Decode the buffer using the dnode tree
-            while (true)
-            {
-                i = dnode[i, bitReader.ReadBit() ? 1 : 0];
-                if (i < 0)
+                i = (short)-(i + 1);
+                if (i == SPEOF)
                 {
-                    i = (short)-(i + 1);
-                    if (i == SPEOF)
-                    {
-                        break;
-                    }
-                    else
-                    {
-                        decoded.Add((byte)i);
-                        i = 0;
-                    }
+                    break;
+                }
+                else
+                {
+                    decoded.Add((byte)i);
+                    i = 0;
                 }
             }
-
-            // Unpack the decoded buffer using the RLE class
-            var unpacked = RLE.UnpackRLE(decoded.ToArray());
-            unpacked.CopyTo(buffer, 0);
-            return unpacked.Count();
         }
 
-        public override long Seek(long offset, SeekOrigin origin) =>
-            throw new NotImplementedException();
-
-        public override void SetLength(long value) => throw new NotImplementedException();
-
-        public override void Write(byte[] buffer, int offset, int count) =>
-            throw new NotImplementedException();
+        // Unpack the decoded buffer using the RLE class
+        var unpacked = RLE.UnpackRLE(decoded.ToArray());
+        unpacked.CopyTo(buffer, 0);
+        return unpacked.Count();
     }
+
+    public override long Seek(long offset, SeekOrigin origin) =>
+        throw new NotImplementedException();
+
+    public override void SetLength(long value) => throw new NotImplementedException();
+
+    public override void Write(byte[] buffer, int offset, int count) =>
+        throw new NotImplementedException();
 }

src/SharpCompress/Compressors/Xz/XZFooter.cs

@@ -22,7 +22,9 @@ public class XZFooter
 
     public static XZFooter FromStream(Stream stream)
     {
-        var footer = new XZFooter(new BinaryReader(stream, Encoding.UTF8, true));
+        var footer = new XZFooter(
+            new BinaryReader(SharpCompressStream.Create(stream, leaveOpen: true), Encoding.UTF8)
+        );
         footer.Process();
         return footer;
     }

src/SharpCompress/Compressors/Xz/XZHeader.cs

@@ -18,7 +18,9 @@ public class XZHeader
 
     public static XZHeader FromStream(Stream stream)
     {
-        var header = new XZHeader(new BinaryReader(stream, Encoding.UTF8, true));
+        var header = new XZHeader(
+            new BinaryReader(SharpCompressStream.Create(stream, leaveOpen: true), Encoding.UTF8)
+        );
         header.Process();
         return header;
     }

src/SharpCompress/Compressors/Xz/XZIndex.cs

@@ -32,7 +32,7 @@ public class XZIndex
     public static XZIndex FromStream(Stream stream, bool indexMarkerAlreadyVerified)
     {
         var index = new XZIndex(
-            new BinaryReader(stream, Encoding.UTF8, true),
+            new BinaryReader(SharpCompressStream.Create(stream, leaveOpen: true), Encoding.UTF8),
             indexMarkerAlreadyVerified
         );
         index.Process();

src/SharpCompress/Compressors/ZStandard/BitOperations.cs

@@ -0,0 +1,311 @@
+// 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 SharpCompress.Compressors.ZStandard.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));
+
+        /// <summary>
+        /// Count the number of leading zero bits in a mask.
+        /// Similar in behavior to the x86 instruction LZCNT.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int LeadingZeroCount(uint value)
+        {
+            // Unguarded fallback contract is 0->31, BSR contract is 0->undefined
+            if (value == 0)
+            {
+                return 32;
+            }
+
+            // 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 31
+                ^ Log2DeBruijn[
+                    // uint|long -> IntPtr cast on 32-bit platforms does expensive overflow checks not needed here
+                    (int)((value * 0x07C4ACDDu) >> 27)
+                ];
+        }
+
+        /// <summary>
+        /// Count the number of leading zero bits in a mask.
+        /// Similar in behavior to the x86 instruction LZCNT.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int LeadingZeroCount(ulong value)
+        {
+            uint hi = (uint)(value >> 32);
+
+            if (hi == 0)
+            {
+                return 32 + LeadingZeroCount((uint)value);
+            }
+
+            return LeadingZeroCount(hi);
+        }
+    }
+}
+
+#endif

src/SharpCompress/Compressors/ZStandard/CompressionStream.cs

@@ -0,0 +1,301 @@
+using System;
+using System.Buffers;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using SharpCompress.Compressors.ZStandard.Unsafe;
+
+namespace SharpCompress.Compressors.ZStandard;
+
+public class CompressionStream : Stream
+{
+    private readonly Stream innerStream;
+    private readonly byte[] outputBuffer;
+    private readonly bool preserveCompressor;
+    private readonly bool leaveOpen;
+    private Compressor? compressor;
+    private ZSTD_outBuffer_s output;
+
+    public CompressionStream(
+        Stream stream,
+        int level = Compressor.DefaultCompressionLevel,
+        int bufferSize = 0,
+        bool leaveOpen = true
+    )
+        : this(stream, new Compressor(level), bufferSize, false, leaveOpen) { }
+
+    public CompressionStream(
+        Stream stream,
+        Compressor compressor,
+        int bufferSize = 0,
+        bool preserveCompressor = true,
+        bool leaveOpen = true
+    )
+    {
+        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;
+        this.compressor = compressor;
+        this.preserveCompressor = preserveCompressor;
+        this.leaveOpen = leaveOpen;
+
+        var outputBufferSize =
+            bufferSize > 0
+                ? bufferSize
+                : (int)Unsafe.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.NotNull().SetParameter(parameter, value);
+    }
+
+    public int GetParameter(ZSTD_cParameter parameter)
+    {
+        EnsureNotDisposed();
+        return compressor.NotNull().GetParameter(parameter);
+    }
+
+    public void LoadDictionary(byte[] dict)
+    {
+        EnsureNotDisposed();
+        compressor.NotNull().LoadDictionary(dict);
+    }
+
+    ~CompressionStream() => Dispose(false);
+
+#if !NETSTANDARD2_0 && !NETFRAMEWORK
+    public override async ValueTask DisposeAsync()
+#else
+    public async Task DisposeAsync()
+#endif
+    {
+        if (compressor == null)
+            return;
+
+        try
+        {
+            await FlushInternalAsync(ZSTD_EndDirective.ZSTD_e_end).ConfigureAwait(false);
+        }
+        finally
+        {
+            ReleaseUnmanagedResources();
+            GC.SuppressFinalize(this);
+        }
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        if (compressor == null)
+            return;
+
+        try
+        {
+            if (disposing)
+                FlushInternal(ZSTD_EndDirective.ZSTD_e_end);
+        }
+        finally
+        {
+            ReleaseUnmanagedResources();
+        }
+    }
+
+    private void ReleaseUnmanagedResources()
+    {
+        if (!preserveCompressor)
+        {
+            compressor.NotNull().Dispose();
+        }
+        compressor = null;
+
+        if (outputBuffer != null)
+        {
+            ArrayPool<byte>.Shared.Return(outputBuffer);
+        }
+
+        if (!leaveOpen)
+        {
+            innerStream.Dispose();
+        }
+    }
+
+    public override void Flush() => FlushInternal(ZSTD_EndDirective.ZSTD_e_flush);
+
+    public override async Task FlushAsync(CancellationToken cancellationToken) =>
+        await FlushInternalAsync(ZSTD_EndDirective.ZSTD_e_flush, cancellationToken)
+            .ConfigureAwait(false);
+
+    private void FlushInternal(ZSTD_EndDirective directive) => WriteInternal(null, directive);
+
+    private async Task FlushInternalAsync(
+        ZSTD_EndDirective directive,
+        CancellationToken cancellationToken = default
+    ) => await WriteInternalAsync(null, directive, cancellationToken).ConfigureAwait(false);
+
+    public override void Write(byte[] buffer, int offset, int count) =>
+        Write(new ReadOnlySpan<byte>(buffer, offset, count));
+
+#if !NETSTANDARD2_0 && !NETFRAMEWORK
+    public override void Write(ReadOnlySpan<byte> buffer) =>
+        WriteInternal(buffer, ZSTD_EndDirective.ZSTD_e_continue);
+#else
+    public void Write(ReadOnlySpan<byte> buffer) =>
+        WriteInternal(buffer, ZSTD_EndDirective.ZSTD_e_continue);
+#endif
+
+    private void WriteInternal(ReadOnlySpan<byte> buffer, ZSTD_EndDirective directive)
+    {
+        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, directive);
+
+            var written = (int)output.pos;
+            if (written > 0)
+                innerStream.Write(outputBuffer, 0, written);
+        } while (
+            directive == ZSTD_EndDirective.ZSTD_e_continue ? input.pos < input.size : remaining > 0
+        );
+    }
+
+#if !NETSTANDARD2_0 && !NETFRAMEWORK
+    private async ValueTask WriteInternalAsync(
+        ReadOnlyMemory<byte>? buffer,
+        ZSTD_EndDirective directive,
+        CancellationToken cancellationToken = default
+    )
+#else
+    private async Task WriteInternalAsync(
+        ReadOnlyMemory<byte>? buffer,
+        ZSTD_EndDirective directive,
+        CancellationToken cancellationToken = default
+    )
+#endif
+
+    {
+        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,
+                directive
+            );
+
+            var written = (int)output.pos;
+            if (written > 0)
+                await innerStream
+                    .WriteAsync(outputBuffer, 0, written, cancellationToken)
+                    .ConfigureAwait(false);
+        } while (
+            directive == ZSTD_EndDirective.ZSTD_e_continue ? input.pos < input.size : remaining > 0
+        );
+    }
+
+#if !NETSTANDARD2_0 && !NETFRAMEWORK
+
+    public override Task WriteAsync(
+        byte[] buffer,
+        int offset,
+        int count,
+        CancellationToken cancellationToken
+    ) => WriteAsync(new ReadOnlyMemory<byte>(buffer, offset, count), cancellationToken).AsTask();
+
+    public override async ValueTask WriteAsync(
+        ReadOnlyMemory<byte> buffer,
+        CancellationToken cancellationToken = default
+    ) =>
+        await WriteInternalAsync(buffer, ZSTD_EndDirective.ZSTD_e_continue, cancellationToken)
+            .ConfigureAwait(false);
+#else
+
+    public override Task WriteAsync(
+        byte[] buffer,
+        int offset,
+        int count,
+        CancellationToken cancellationToken
+    ) => WriteAsync(new ReadOnlyMemory<byte>(buffer, offset, count), cancellationToken);
+
+    public async Task WriteAsync(
+        ReadOnlyMemory<byte> buffer,
+        CancellationToken cancellationToken = default
+    ) =>
+        await WriteInternalAsync(buffer, ZSTD_EndDirective.ZSTD_e_continue, 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
+                .NotNull()
+                .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));
+    }
+
+    public void SetPledgedSrcSize(ulong pledgedSrcSize)
+    {
+        EnsureNotDisposed();
+        compressor.NotNull().SetPledgedSrcSize(pledgedSrcSize);
+    }
+}

src/SharpCompress/Compressors/ZStandard/Compressor.cs

@@ -0,0 +1,204 @@
+using System;
+using SharpCompress.Compressors.ZStandard.Unsafe;
+
+namespace SharpCompress.Compressors.ZStandard;
+
+public unsafe class Compressor : IDisposable
+{
+    /// <summary>
+    /// Minimum negative compression level allowed
+    /// </summary>
+    public static int MinCompressionLevel => Unsafe.Methods.ZSTD_minCLevel();
+
+    /// <summary>
+    /// Maximum compression level available
+    /// </summary>
+    public static int MaxCompressionLevel => Unsafe.Methods.ZSTD_maxCLevel();
+
+    /// <summary>
+    /// Default compression level
+    /// </summary>
+    /// <see cref="Unsafe.Methods.ZSTD_defaultCLevel"/>
+    public const int DefaultCompressionLevel = 3;
+
+    private int level = DefaultCompressionLevel;
+
+    private readonly SafeCctxHandle handle;
+
+    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)
+    {
+        using var cctx = handle.Acquire();
+        Unsafe.Methods.ZSTD_CCtx_setParameter(cctx, parameter, value).EnsureZstdSuccess();
+    }
+
+    public int GetParameter(ZSTD_cParameter parameter)
+    {
+        using var cctx = handle.Acquire();
+        int value;
+        Unsafe.Methods.ZSTD_CCtx_getParameter(cctx, parameter, &value).EnsureZstdSuccess();
+        return value;
+    }
+
+    public void LoadDictionary(byte[] dict)
+    {
+        var dictReadOnlySpan = new ReadOnlySpan<byte>(dict);
+        LoadDictionary(dictReadOnlySpan);
+    }
+
+    public void LoadDictionary(ReadOnlySpan<byte> dict)
+    {
+        using var cctx = handle.Acquire();
+        fixed (byte* dictPtr = dict)
+            Unsafe
+                .Methods.ZSTD_CCtx_loadDictionary(cctx, dictPtr, (nuint)dict.Length)
+                .EnsureZstdSuccess();
+    }
+
+    public Compressor(int level = DefaultCompressionLevel)
+    {
+        handle = SafeCctxHandle.Create();
+        Level = level;
+    }
+
+    public static int GetCompressBound(int length) =>
+        (int)Unsafe.Methods.ZSTD_compressBound((nuint)length);
+
+    public static ulong GetCompressBoundLong(ulong length) =>
+        Unsafe.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)
+    {
+        fixed (byte* srcPtr = src)
+        fixed (byte* destPtr = dest)
+        {
+            using var cctx = handle.Acquire();
+            return (int)
+                Unsafe
+                    .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)
+    {
+        fixed (byte* srcPtr = src)
+        fixed (byte* destPtr = dest)
+        {
+            nuint returnValue;
+            using (var cctx = handle.Acquire())
+            {
+                returnValue = Unsafe.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
+        );
+
+    public void Dispose()
+    {
+        handle.Dispose();
+        GC.SuppressFinalize(this);
+    }
+
+    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)
+        {
+            using var cctx = handle.Acquire();
+            return Unsafe
+                .Methods.ZSTD_compressStream2(cctx, outputPtr, inputPtr, directive)
+                .EnsureZstdSuccess();
+        }
+    }
+
+    public void SetPledgedSrcSize(ulong pledgedSrcSize)
+    {
+        using var cctx = handle.Acquire();
+        Unsafe.Methods.ZSTD_CCtx_setPledgedSrcSize(cctx, pledgedSrcSize).EnsureZstdSuccess();
+    }
+}

src/SharpCompress/Compressors/ZStandard/Constants.cs

@@ -0,0 +1,8 @@
+namespace SharpCompress.Compressors.ZStandard;
+
+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/ZStandard/DecompressionStream.cs

@@ -0,0 +1,293 @@
+using System;
+using System.Buffers;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using SharpCompress.Compressors.ZStandard.Unsafe;
+
+namespace SharpCompress.Compressors.ZStandard;
+
+public class DecompressionStream : Stream
+{
+    private readonly Stream innerStream;
+    private readonly byte[] inputBuffer;
+    private readonly int inputBufferSize;
+    private readonly bool preserveDecompressor;
+    private readonly bool leaveOpen;
+    private readonly bool checkEndOfStream;
+    private Decompressor? decompressor;
+    private ZSTD_inBuffer_s input;
+    private nuint lastDecompressResult = 0;
+    private bool contextDrained = true;
+
+    public DecompressionStream(
+        Stream stream,
+        int bufferSize = 0,
+        bool checkEndOfStream = true,
+        bool leaveOpen = true
+    )
+        : this(stream, new Decompressor(), bufferSize, checkEndOfStream, false, leaveOpen) { }
+
+    public DecompressionStream(
+        Stream stream,
+        Decompressor decompressor,
+        int bufferSize = 0,
+        bool checkEndOfStream = true,
+        bool preserveDecompressor = true,
+        bool leaveOpen = true
+    )
+    {
+        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;
+        this.decompressor = decompressor;
+        this.preserveDecompressor = preserveDecompressor;
+        this.leaveOpen = leaveOpen;
+        this.checkEndOfStream = checkEndOfStream;
+
+        inputBufferSize =
+            bufferSize > 0
+                ? bufferSize
+                : (int)Unsafe.Methods.ZSTD_DStreamInSize().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.NotNull().SetParameter(parameter, value);
+    }
+
+    public int GetParameter(ZSTD_dParameter parameter)
+    {
+        EnsureNotDisposed();
+        return decompressor.NotNull().GetParameter(parameter);
+    }
+
+    public void LoadDictionary(byte[] dict)
+    {
+        EnsureNotDisposed();
+        decompressor.NotNull().LoadDictionary(dict);
+    }
+
+    ~DecompressionStream() => Dispose(false);
+
+    protected override void Dispose(bool disposing)
+    {
+        if (decompressor == null)
+            return;
+
+        if (!preserveDecompressor)
+        {
+            decompressor.Dispose();
+        }
+        decompressor = null;
+
+        if (inputBuffer != null)
+        {
+            ArrayPool<byte>.Shared.Return(inputBuffer);
+        }
+
+        if (!leaveOpen)
+        {
+            innerStream.Dispose();
+        }
+    }
+
+    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();
+
+        // Guard against infinite loop (output.pos would never become non-zero)
+        if (buffer.Length == 0)
+        {
+            return 0;
+        }
+
+        var output = new ZSTD_outBuffer_s { pos = 0, size = (nuint)buffer.Length };
+        while (true)
+        {
+            // If there is still input available, or there might be data buffered in the decompressor context, flush that out
+            while (input.pos < input.size || !contextDrained)
+            {
+                nuint oldInputPos = input.pos;
+                nuint result = DecompressStream(ref output, buffer);
+                if (output.pos > 0 || oldInputPos != input.pos)
+                {
+                    // Keep result from last decompress call that made some progress, so we known if we're at end of frame
+                    lastDecompressResult = result;
+                }
+                // If decompression filled the output buffer, there might still be data buffered in the decompressor context
+                contextDrained = output.pos < output.size;
+                // If we have data to return, return it immediately, so we won't stall on Read
+                if (output.pos > 0)
+                {
+                    return (int)output.pos;
+                }
+            }
+
+            // Otherwise, read some more input
+            int bytesRead;
+            if ((bytesRead = innerStream.Read(inputBuffer, 0, inputBufferSize)) == 0)
+            {
+                if (checkEndOfStream && lastDecompressResult != 0)
+                {
+                    throw new EndOfStreamException("Premature end of stream");
+                }
+
+                return 0;
+            }
+
+            input.size = (nuint)bytesRead;
+            input.pos = 0;
+        }
+    }
+
+#if !NETSTANDARD2_0 && !NETFRAMEWORK
+    public override Task<int> ReadAsync(
+        byte[] buffer,
+        int offset,
+        int count,
+        CancellationToken cancellationToken
+    ) => ReadAsync(new Memory<byte>(buffer, offset, count), cancellationToken).AsTask();
+
+    public override async ValueTask<int> ReadAsync(
+        Memory<byte> buffer,
+        CancellationToken cancellationToken = default
+    )
+#else
+
+    public override Task<int> ReadAsync(
+        byte[] buffer,
+        int offset,
+        int count,
+        CancellationToken cancellationToken
+    ) => ReadAsync(new Memory<byte>(buffer, offset, count), cancellationToken);
+
+    public async Task<int> ReadAsync(
+        Memory<byte> buffer,
+        CancellationToken cancellationToken = default
+    )
+#endif
+    {
+        EnsureNotDisposed();
+
+        // Guard against infinite loop (output.pos would never become non-zero)
+        if (buffer.Length == 0)
+        {
+            return 0;
+        }
+
+        var output = new ZSTD_outBuffer_s { pos = 0, size = (nuint)buffer.Length };
+        while (true)
+        {
+            // If there is still input available, or there might be data buffered in the decompressor context, flush that out
+            while (input.pos < input.size || !contextDrained)
+            {
+                nuint oldInputPos = input.pos;
+                nuint result = DecompressStream(ref output, buffer.Span);
+                if (output.pos > 0 || oldInputPos != input.pos)
+                {
+                    // Keep result from last decompress call that made some progress, so we known if we're at end of frame
+                    lastDecompressResult = result;
+                }
+                // If decompression filled the output buffer, there might still be data buffered in the decompressor context
+                contextDrained = output.pos < output.size;
+                // If we have data to return, return it immediately, so we won't stall on Read
+                if (output.pos > 0)
+                {
+                    return (int)output.pos;
+                }
+            }
+
+            // Otherwise, read some more input
+            int bytesRead;
+            if (
+                (
+                    bytesRead = await innerStream
+                        .ReadAsync(inputBuffer, 0, inputBufferSize, cancellationToken)
+                        .ConfigureAwait(false)
+                ) == 0
+            )
+            {
+                if (checkEndOfStream && lastDecompressResult != 0)
+                {
+                    throw new EndOfStreamException("Premature end of stream");
+                }
+
+                return 0;
+            }
+
+            input.size = (nuint)bytesRead;
+            input.pos = 0;
+        }
+    }
+
+    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.NotNull().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 || NETFRAMEWORK
+    public virtual Task DisposeAsync()
+    {
+        try
+        {
+            Dispose();
+            return Task.CompletedTask;
+        }
+        catch (Exception exc)
+        {
+            return Task.FromException(exc);
+        }
+    }
+#endif
+}

src/SharpCompress/Compressors/ZStandard/Decompressor.cs

@@ -0,0 +1,176 @@
+using System;
+using SharpCompress.Compressors.ZStandard.Unsafe;
+
+namespace SharpCompress.Compressors.ZStandard;
+
+public unsafe class Decompressor : IDisposable
+{
+    private readonly SafeDctxHandle handle;
+
+    public Decompressor()
+    {
+        handle = SafeDctxHandle.Create();
+    }
+
+    public void SetParameter(ZSTD_dParameter parameter, int value)
+    {
+        using var dctx = handle.Acquire();
+        Unsafe.Methods.ZSTD_DCtx_setParameter(dctx, parameter, value).EnsureZstdSuccess();
+    }
+
+    public int GetParameter(ZSTD_dParameter parameter)
+    {
+        using var dctx = handle.Acquire();
+        int value;
+        Unsafe.Methods.ZSTD_DCtx_getParameter(dctx, parameter, &value).EnsureZstdSuccess();
+        return value;
+    }
+
+    public void LoadDictionary(byte[] dict)
+    {
+        var dictReadOnlySpan = new ReadOnlySpan<byte>(dict);
+        this.LoadDictionary(dictReadOnlySpan);
+    }
+
+    public void LoadDictionary(ReadOnlySpan<byte> dict)
+    {
+        using var dctx = handle.Acquire();
+        fixed (byte* dictPtr = dict)
+            Unsafe
+                .Methods.ZSTD_DCtx_loadDictionary(dctx, dictPtr, (nuint)dict.Length)
+                .EnsureZstdSuccess();
+    }
+
+    public static ulong GetDecompressedSize(ReadOnlySpan<byte> src)
+    {
+        fixed (byte* srcPtr = src)
+            return Unsafe
+                .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)
+    {
+        fixed (byte* srcPtr = src)
+        fixed (byte* destPtr = dest)
+        {
+            using var dctx = handle.Acquire();
+            return (int)
+                Unsafe
+                    .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)
+    {
+        fixed (byte* srcPtr = src)
+        fixed (byte* destPtr = dest)
+        {
+            nuint returnValue;
+            using (var dctx = handle.Acquire())
+            {
+                returnValue = Unsafe.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
+        );
+
+    public void Dispose()
+    {
+        handle.Dispose();
+        GC.SuppressFinalize(this);
+    }
+
+    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)
+        {
+            using var dctx = handle.Acquire();
+            return Unsafe
+                .Methods.ZSTD_decompressStream(dctx, outputPtr, inputPtr)
+                .EnsureZstdSuccess();
+        }
+    }
+}

src/SharpCompress/Compressors/ZStandard/JobThreadPool.cs

@@ -0,0 +1,141 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Threading;
+
+namespace SharpCompress.Compressors.ZStandard;
+
+internal unsafe class JobThreadPool : IDisposable
+{
+    private int numThreads;
+    private readonly List<JobThread> threads;
+    private readonly BlockingCollection<Job> queue;
+
+    private struct Job
+    {
+        public void* function;
+        public void* opaque;
+    }
+
+    private class JobThread
+    {
+        private Thread Thread { get; }
+        public CancellationTokenSource CancellationTokenSource { get; }
+
+        public JobThread(Thread thread)
+        {
+            CancellationTokenSource = new CancellationTokenSource();
+            Thread = thread;
+        }
+
+        public void Start()
+        {
+            Thread.Start(this);
+        }
+
+        public void Cancel()
+        {
+            CancellationTokenSource.Cancel();
+        }
+
+        public void Join()
+        {
+            Thread.Join();
+        }
+    }
+
+    private void Worker(object? obj)
+    {
+        if (obj is not JobThread poolThread)
+            return;
+
+        var cancellationToken = poolThread.CancellationTokenSource.Token;
+        while (!queue.IsCompleted && !cancellationToken.IsCancellationRequested)
+        {
+            try
+            {
+                if (queue.TryTake(out var job, -1, cancellationToken))
+                    ((delegate* managed<void*, void>)job.function)(job.opaque);
+            }
+            catch (InvalidOperationException) { }
+            catch (OperationCanceledException) { }
+        }
+    }
+
+    public JobThreadPool(int num, int queueSize)
+    {
+        numThreads = num;
+        queue = new BlockingCollection<Job>(queueSize + 1);
+        threads = new List<JobThread>(num);
+        for (var i = 0; i < numThreads; i++)
+            CreateThread();
+    }
+
+    private void CreateThread()
+    {
+        var poolThread = new JobThread(new Thread(Worker));
+        threads.Add(poolThread);
+        poolThread.Start();
+    }
+
+    public void Resize(int num)
+    {
+        lock (threads)
+        {
+            if (num < numThreads)
+            {
+                for (var i = numThreads - 1; i >= num; i--)
+                {
+                    threads[i].Cancel();
+                    threads.RemoveAt(i);
+                }
+            }
+            else
+            {
+                for (var i = numThreads; i < num; i++)
+                    CreateThread();
+            }
+        }
+
+        numThreads = num;
+    }
+
+    public void Add(void* function, void* opaque)
+    {
+        queue.Add(new Job { function = function, opaque = opaque });
+    }
+
+    public bool TryAdd(void* function, void* opaque)
+    {
+        return queue.TryAdd(new Job { function = function, opaque = opaque });
+    }
+
+    public void Join(bool cancel = true)
+    {
+        queue.CompleteAdding();
+        List<JobThread> jobThreads;
+        lock (threads)
+            jobThreads = new List<JobThread>(threads);
+
+        if (cancel)
+        {
+            foreach (var thread in jobThreads)
+                thread.Cancel();
+        }
+
+        foreach (var thread in jobThreads)
+            thread.Join();
+    }
+
+    public void Dispose()
+    {
+        queue.Dispose();
+    }
+
+    public int Size()
+    {
+        // todo not implemented
+        // https://github.com/dotnet/runtime/issues/24200
+        return 0;
+    }
+}

src/SharpCompress/Compressors/ZStandard/SafeHandles.cs

@@ -0,0 +1,163 @@
+using System;
+using System.Runtime.InteropServices;
+using SharpCompress.Compressors.ZStandard.Unsafe;
+
+namespace SharpCompress.Compressors.ZStandard;
+
+/// <summary>
+/// Provides the base class for ZstdSharp <see cref="SafeHandle"/> implementations.
+/// </summary>
+/// <remarks>
+/// Even though ZstdSharp is a managed library, its internals are using unmanaged
+/// memory and we are using safe handles in the library's high-level API to ensure
+/// proper disposal of unmanaged resources and increase safety.
+/// </remarks>
+/// <seealso cref="SafeCctxHandle"/>
+/// <seealso cref="SafeDctxHandle"/>
+internal abstract unsafe class SafeZstdHandle : SafeHandle
+{
+    /// <summary>
+    /// Parameterless constructor is hidden. Use the static <c>Create</c> factory
+    /// method to create a new safe handle instance.
+    /// </summary>
+    protected SafeZstdHandle()
+        : base(IntPtr.Zero, true) { }
+
+    public sealed override bool IsInvalid => handle == IntPtr.Zero;
+}
+
+/// <summary>
+/// Safely wraps an unmanaged Zstd compression context.
+/// </summary>
+internal sealed unsafe class SafeCctxHandle : SafeZstdHandle
+{
+    /// <inheritdoc/>
+    private SafeCctxHandle() { }
+
+    /// <summary>
+    /// Creates a new instance of <see cref="SafeCctxHandle"/>.
+    /// </summary>
+    /// <returns></returns>
+    /// <exception cref="ZstdException">Creation failed.</exception>
+    public static SafeCctxHandle Create()
+    {
+        var safeHandle = new SafeCctxHandle();
+        bool success = false;
+        try
+        {
+            var cctx = Unsafe.Methods.ZSTD_createCCtx();
+            if (cctx == null)
+                throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_GENERIC, "Failed to create cctx");
+            safeHandle.SetHandle((IntPtr)cctx);
+            success = true;
+        }
+        finally
+        {
+            if (!success)
+            {
+                safeHandle.SetHandleAsInvalid();
+            }
+        }
+        return safeHandle;
+    }
+
+    /// <summary>
+    /// Acquires a reference to the safe handle.
+    /// </summary>
+    /// <returns>
+    /// A <see cref="SafeHandleHolder{T}"/> instance that can be implicitly converted to a pointer
+    /// to <see cref="ZSTD_CCtx_s"/>.
+    /// </returns>
+    public SafeHandleHolder<ZSTD_CCtx_s> Acquire() => new(this);
+
+    protected override bool ReleaseHandle()
+    {
+        return Unsafe.Methods.ZSTD_freeCCtx((ZSTD_CCtx_s*)handle) == 0;
+    }
+}
+
+/// <summary>
+/// Safely wraps an unmanaged Zstd compression context.
+/// </summary>
+internal sealed unsafe class SafeDctxHandle : SafeZstdHandle
+{
+    /// <inheritdoc/>
+    private SafeDctxHandle() { }
+
+    /// <summary>
+    /// Creates a new instance of <see cref="SafeDctxHandle"/>.
+    /// </summary>
+    /// <returns></returns>
+    /// <exception cref="ZstdException">Creation failed.</exception>
+    public static SafeDctxHandle Create()
+    {
+        var safeHandle = new SafeDctxHandle();
+        bool success = false;
+        try
+        {
+            var dctx = Unsafe.Methods.ZSTD_createDCtx();
+            if (dctx == null)
+                throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_GENERIC, "Failed to create dctx");
+            safeHandle.SetHandle((IntPtr)dctx);
+            success = true;
+        }
+        finally
+        {
+            if (!success)
+            {
+                safeHandle.SetHandleAsInvalid();
+            }
+        }
+        return safeHandle;
+    }
+
+    /// <summary>
+    /// Acquires a reference to the safe handle.
+    /// </summary>
+    /// <returns>
+    /// A <see cref="SafeHandleHolder{T}"/> instance that can be implicitly converted to a pointer
+    /// to <see cref="ZSTD_DCtx_s"/>.
+    /// </returns>
+    public SafeHandleHolder<ZSTD_DCtx_s> Acquire() => new(this);
+
+    protected override bool ReleaseHandle()
+    {
+        return Unsafe.Methods.ZSTD_freeDCtx((ZSTD_DCtx_s*)handle) == 0;
+    }
+}
+
+/// <summary>
+/// Provides a convenient interface to safely acquire pointers of a specific type
+/// from a <see cref="SafeHandle"/>, by utilizing <see langword="using"/> blocks.
+/// </summary>
+/// <typeparam name="T">The type of pointers to return.</typeparam>
+/// <remarks>
+/// Safe handle holders can be <see cref="Dispose"/>d to decrement the safe handle's
+/// reference count, and can be implicitly converted to pointers to <see cref="T"/>.
+/// </remarks>
+internal unsafe ref struct SafeHandleHolder<T>
+    where T : unmanaged
+{
+    private readonly SafeHandle _handle;
+
+    private bool _refAdded;
+
+    public SafeHandleHolder(SafeHandle safeHandle)
+    {
+        _handle = safeHandle;
+        _refAdded = false;
+        safeHandle.DangerousAddRef(ref _refAdded);
+    }
+
+    public static implicit operator T*(SafeHandleHolder<T> holder) =>
+        (T*)holder._handle.DangerousGetHandle();
+
+    public void Dispose()
+    {
+        if (_refAdded)
+        {
+            _handle.DangerousRelease();
+            _refAdded = false;
+        }
+    }
+}

src/SharpCompress/Compressors/ZStandard/SynchronizationWrapper.cs

@@ -0,0 +1,22 @@
+using System.Threading;
+
+namespace SharpCompress.Compressors.ZStandard;
+
+internal static unsafe class SynchronizationWrapper
+{
+    private static object UnwrapObject(void** obj) => UnmanagedObject.Unwrap<object>(*obj);
+
+    public static void Init(void** obj) => *obj = UnmanagedObject.Wrap(new object());
+
+    public static void Free(void** obj) => UnmanagedObject.Free(*obj);
+
+    public static void Enter(void** obj) => Monitor.Enter(UnwrapObject(obj));
+
+    public static void Exit(void** obj) => Monitor.Exit(UnwrapObject(obj));
+
+    public static void Pulse(void** obj) => Monitor.Pulse(UnwrapObject(obj));
+
+    public static void PulseAll(void** obj) => Monitor.PulseAll(UnwrapObject(obj));
+
+    public static void Wait(void** mutex) => Monitor.Wait(UnwrapObject(mutex));
+}

src/SharpCompress/Compressors/ZStandard/ThrowHelper.cs

@@ -0,0 +1,48 @@
+using SharpCompress.Compressors.ZStandard.Unsafe;
+
+namespace SharpCompress.Compressors.ZStandard;
+
+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 (Unsafe.Methods.ZSTD_isError(returnValue))
+            ThrowException(returnValue, Unsafe.Methods.ZSTD_getErrorName(returnValue));
+
+        return returnValue;
+    }
+
+    public static nuint EnsureZdictSuccess(this nuint returnValue)
+    {
+        if (Unsafe.Methods.ZDICT_isError(returnValue))
+            ThrowException(returnValue, Unsafe.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/ZStandard/UnmanagedObject.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace SharpCompress.Compressors.ZStandard;
+
+/*
+ * Wrap object to void* to make it unmanaged
+ */
+internal static unsafe class UnmanagedObject
+{
+    public static void* Wrap(object obj) => (void*)GCHandle.ToIntPtr(GCHandle.Alloc(obj));
+
+    private static GCHandle UnwrapGcHandle(void* value) => GCHandle.FromIntPtr((IntPtr)value);
+
+    public static T Unwrap<T>(void* value) => (T)UnwrapGcHandle(value).Target!;
+
+    public static void Free(void* value) => UnwrapGcHandle(value).Free();
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/Allocations.cs

@@ -0,0 +1,52 @@
+using System.Runtime.CompilerServices;
+using static SharpCompress.Compressors.ZStandard.UnsafeHelper;
+
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public static unsafe partial class Methods
+{
+    /* custom memory allocation functions */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static void* ZSTD_customMalloc(nuint size, ZSTD_customMem customMem)
+    {
+        if (customMem.customAlloc != null)
+            return ((delegate* managed<void*, nuint, void*>)customMem.customAlloc)(
+                customMem.opaque,
+                size
+            );
+        return malloc(size);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static void* ZSTD_customCalloc(nuint size, ZSTD_customMem customMem)
+    {
+        if (customMem.customAlloc != null)
+        {
+            /* calloc implemented as malloc+memset;
+             * not as efficient as calloc, but next best guess for custom malloc */
+            void* ptr = ((delegate* managed<void*, nuint, void*>)customMem.customAlloc)(
+                customMem.opaque,
+                size
+            );
+            memset(ptr, 0, (uint)size);
+            return ptr;
+        }
+
+        return calloc(1, size);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static void ZSTD_customFree(void* ptr, ZSTD_customMem customMem)
+    {
+        if (ptr != null)
+        {
+            if (customMem.customFree != null)
+                ((delegate* managed<void*, void*, void>)customMem.customFree)(
+                    customMem.opaque,
+                    ptr
+                );
+            else
+                free(ptr);
+        }
+    }
+}

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

@@ -0,0 +1,14 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/* 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 struct BIT_CStream_t
+{
+    public nuint bitContainer;
+    public uint bitPos;
+    public sbyte* startPtr;
+    public sbyte* ptr;
+    public sbyte* endPtr;
+}

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

@@ -0,0 +1,16 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public enum BIT_DStream_status
+{
+    /* fully refilled */
+    BIT_DStream_unfinished = 0,
+
+    /* still some bits left in bitstream */
+    BIT_DStream_endOfBuffer = 1,
+
+    /* bitstream entirely consumed, bit-exact */
+    BIT_DStream_completed = 2,
+
+    /* user requested more bits than present in bitstream */
+    BIT_DStream_overflow = 3,
+}

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

@@ -0,0 +1,13 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/*-********************************************
+ *  bitStream decoding API (read backward)
+ **********************************************/
+public unsafe struct BIT_DStream_t
+{
+    public nuint bitContainer;
+    public uint bitsConsumed;
+    public sbyte* ptr;
+    public sbyte* start;
+    public sbyte* limitPtr;
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/Bits.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using static SharpCompress.Compressors.ZStandard.UnsafeHelper;
+
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public static unsafe partial class Methods
+{
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static uint ZSTD_countTrailingZeros32(uint val)
+    {
+        assert(val != 0);
+        return (uint)BitOperations.TrailingZeroCount(val);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static uint ZSTD_countLeadingZeros32(uint val)
+    {
+        assert(val != 0);
+        return (uint)BitOperations.LeadingZeroCount(val);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static uint ZSTD_countTrailingZeros64(ulong val)
+    {
+        assert(val != 0);
+        return (uint)BitOperations.TrailingZeroCount(val);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static uint ZSTD_countLeadingZeros64(ulong val)
+    {
+        assert(val != 0);
+        return (uint)BitOperations.LeadingZeroCount(val);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static uint ZSTD_NbCommonBytes(nuint val)
+    {
+        assert(val != 0);
+        if (BitConverter.IsLittleEndian)
+        {
+            return MEM_64bits
+                ? (uint)BitOperations.TrailingZeroCount(val) >> 3
+                : (uint)BitOperations.TrailingZeroCount((uint)val) >> 3;
+        }
+
+        return MEM_64bits
+            ? (uint)BitOperations.LeadingZeroCount(val) >> 3
+            : (uint)BitOperations.LeadingZeroCount((uint)val) >> 3;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static uint ZSTD_highbit32(uint val)
+    {
+        assert(val != 0);
+        return (uint)BitOperations.Log2(val);
+    }
+}

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

@@ -0,0 +1,739 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using static SharpCompress.Compressors.ZStandard.UnsafeHelper;
+#if NETCOREAPP3_0_OR_GREATER
+using System.Runtime.Intrinsics.X86;
+#endif
+
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public static unsafe partial class Methods
+{
+#if NET7_0_OR_GREATER
+    private static ReadOnlySpan<uint> Span_BIT_mask =>
+        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,
+        };
+    private static uint* BIT_mask =>
+        (uint*)
+            System.Runtime.CompilerServices.Unsafe.AsPointer(
+                ref MemoryMarshal.GetReference(Span_BIT_mask)
+            );
+#else
+
+    private static readonly 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,
+        }
+    );
+#endif
+    /*-**************************************************************
+     *  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(ref 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 - sizeof(nuint);
+        if (dstCapacity <= (nuint)sizeof(nuint))
+            return unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_dstSize_tooSmall));
+        return 0;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static nuint BIT_getLowerBits(nuint bitContainer, uint nbBits)
+    {
+        assert(nbBits < sizeof(uint) * 32 / sizeof(uint));
+#if NETCOREAPP3_1_OR_GREATER
+        if (Bmi2.X64.IsSupported)
+        {
+            return (nuint)Bmi2.X64.ZeroHighBits(bitContainer, nbBits);
+        }
+
+        if (Bmi2.IsSupported)
+        {
+            return Bmi2.ZeroHighBits((uint)bitContainer, nbBits);
+        }
+#endif
+
+        return bitContainer & BIT_mask[nbBits];
+    }
+
+    /*! 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(
+        ref nuint bitC_bitContainer,
+        ref uint bitC_bitPos,
+        nuint value,
+        uint nbBits
+    )
+    {
+        assert(nbBits < sizeof(uint) * 32 / sizeof(uint));
+        assert(nbBits + bitC_bitPos < (uint)(sizeof(nuint) * 8));
+        bitC_bitContainer |= BIT_getLowerBits(value, 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(
+        ref nuint bitC_bitContainer,
+        ref uint bitC_bitPos,
+        nuint value,
+        uint nbBits
+    )
+    {
+        assert(value >> (int)nbBits == 0);
+        assert(nbBits + bitC_bitPos < (uint)(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(
+        ref nuint bitC_bitContainer,
+        ref uint bitC_bitPos,
+        ref sbyte* bitC_ptr,
+        sbyte* bitC_endPtr
+    )
+    {
+        nuint nbBytes = bitC_bitPos >> 3;
+        assert(bitC_bitPos < (uint)(sizeof(nuint) * 8));
+        assert(bitC_ptr <= bitC_endPtr);
+        MEM_writeLEST(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(
+        ref nuint bitC_bitContainer,
+        ref uint bitC_bitPos,
+        ref sbyte* bitC_ptr,
+        sbyte* bitC_endPtr
+    )
+    {
+        nuint nbBytes = bitC_bitPos >> 3;
+        assert(bitC_bitPos < (uint)(sizeof(nuint) * 8));
+        assert(bitC_ptr <= bitC_endPtr);
+        MEM_writeLEST(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(
+        ref nuint bitC_bitContainer,
+        ref uint bitC_bitPos,
+        sbyte* bitC_ptr,
+        sbyte* bitC_endPtr,
+        sbyte* bitC_startPtr
+    )
+    {
+        BIT_addBitsFast(ref bitC_bitContainer, ref bitC_bitPos, 1, 1);
+        BIT_flushBits(ref bitC_bitContainer, ref bitC_bitPos, ref bitC_ptr, bitC_endPtr);
+        if (bitC_ptr >= bitC_endPtr)
+            return 0;
+        return (nuint)(bitC_ptr - bitC_startPtr) + (nuint)(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)
+        {
+            *bitD = new BIT_DStream_t();
+            return unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong));
+        }
+
+        bitD->start = (sbyte*)srcBuffer;
+        bitD->limitPtr = bitD->start + sizeof(nuint);
+        if (srcSize >= (nuint)sizeof(nuint))
+        {
+            bitD->ptr = (sbyte*)srcBuffer + srcSize - sizeof(nuint);
+            bitD->bitContainer = MEM_readLEST(bitD->ptr);
+            {
+                byte lastByte = ((byte*)srcBuffer)[srcSize - 1];
+                bitD->bitsConsumed = lastByte != 0 ? 8 - ZSTD_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] << sizeof(nuint) * 8 - 16;
+                    goto case 6;
+                case 6:
+                    bitD->bitContainer += (nuint)((byte*)srcBuffer)[5] << sizeof(nuint) * 8 - 24;
+                    goto case 5;
+                case 5:
+                    bitD->bitContainer += (nuint)((byte*)srcBuffer)[4] << 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 - ZSTD_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)(sizeof(nuint) * 8 - 1);
+        assert(nbBits < sizeof(uint) * 32 / sizeof(uint));
+#if NETCOREAPP3_1_OR_GREATER
+        if (Bmi2.X64.IsSupported)
+        {
+            return (nuint)Bmi2.X64.ZeroHighBits(bitContainer >> (int)(start & regMask), nbBits);
+        }
+
+        if (Bmi2.IsSupported)
+        {
+            return Bmi2.ZeroHighBits((uint)(bitContainer >> (int)(start & regMask)), nbBits);
+        }
+#endif
+
+        return (nuint)(bitContainer >> (int)(start & regMask) & ((ulong)1 << (int)nbBits) - 1);
+    }
+
+    /*! 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)(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)(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 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_reloadDStream_internal() :
+     *  Simple variant of BIT_reloadDStream(), with two conditions:
+     *  1. bitstream is valid : bitsConsumed <= sizeof(bitD->bitContainer)*8
+     *  2. look window is valid after shifted down : bitD->ptr >= bitD->start
+     */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static BIT_DStream_status BIT_reloadDStream_internal(BIT_DStream_t* bitD)
+    {
+        assert(bitD->bitsConsumed <= (uint)(sizeof(nuint) * 8));
+        bitD->ptr -= bitD->bitsConsumed >> 3;
+        assert(bitD->ptr >= bitD->start);
+        bitD->bitsConsumed &= 7;
+        bitD->bitContainer = MEM_readLEST(bitD->ptr);
+        return BIT_DStream_status.BIT_DStream_unfinished;
+    }
+
+    /*! 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;
+        return BIT_reloadDStream_internal(bitD);
+    }
+
+#if NET7_0_OR_GREATER
+    private static ReadOnlySpan<byte> Span_static_zeroFilled =>
+        new byte[] { 0, 0, 0, 0, 0, 0, 0, 0 };
+    private static nuint* static_zeroFilled =>
+        (nuint*)
+            System.Runtime.CompilerServices.Unsafe.AsPointer(
+                ref MemoryMarshal.GetReference(Span_static_zeroFilled)
+            );
+#else
+
+    private static readonly nuint* static_zeroFilled = (nuint*)GetArrayPointer(
+        new byte[] { 0, 0, 0, 0, 0, 0, 0, 0 }
+    );
+#endif
+    /*! BIT_reloadDStream() :
+     *  Refill `bitD` from buffer previously set in BIT_initDStream() .
+     *  This function is safe, it guarantees it will not never 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 > (uint)(sizeof(nuint) * 8))
+        {
+            bitD->ptr = (sbyte*)&static_zeroFilled[0];
+            return BIT_DStream_status.BIT_DStream_overflow;
+        }
+
+        assert(bitD->ptr >= bitD->start);
+        if (bitD->ptr >= bitD->limitPtr)
+        {
+            return BIT_reloadDStream_internal(bitD);
+        }
+
+        if (bitD->ptr == bitD->start)
+        {
+            if (bitD->bitsConsumed < (uint)(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(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 == (uint)(sizeof(nuint) * 8)
+            ? 1U
+            : 0U;
+    }
+
+    /*-********************************************************
+     *  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(ref BIT_DStream_t bitD, void* srcBuffer, nuint srcSize)
+    {
+        if (srcSize < 1)
+        {
+            bitD = new BIT_DStream_t();
+            return unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_srcSize_wrong));
+        }
+
+        bitD.start = (sbyte*)srcBuffer;
+        bitD.limitPtr = bitD.start + sizeof(nuint);
+        if (srcSize >= (nuint)sizeof(nuint))
+        {
+            bitD.ptr = (sbyte*)srcBuffer + srcSize - sizeof(nuint);
+            bitD.bitContainer = MEM_readLEST(bitD.ptr);
+            {
+                byte lastByte = ((byte*)srcBuffer)[srcSize - 1];
+                bitD.bitsConsumed = lastByte != 0 ? 8 - ZSTD_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] << sizeof(nuint) * 8 - 16;
+                    goto case 6;
+                case 6:
+                    bitD.bitContainer += (nuint)((byte*)srcBuffer)[5] << sizeof(nuint) * 8 - 24;
+                    goto case 5;
+                case 5:
+                    bitD.bitContainer += (nuint)((byte*)srcBuffer)[4] << 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 - ZSTD_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;
+    }
+
+    /*! 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(nuint bitD_bitContainer, uint bitD_bitsConsumed, uint nbBits)
+    {
+        return BIT_getMiddleBits(
+            bitD_bitContainer,
+            (uint)(sizeof(nuint) * 8) - bitD_bitsConsumed - nbBits,
+            nbBits
+        );
+    }
+
+    /*! BIT_lookBitsFast() :
+     *  unsafe version; only works if nbBits >= 1 */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static nuint BIT_lookBitsFast(
+        nuint bitD_bitContainer,
+        uint bitD_bitsConsumed,
+        uint nbBits
+    )
+    {
+        uint regMask = (uint)(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(ref uint bitD_bitsConsumed, 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(
+        nuint bitD_bitContainer,
+        ref uint bitD_bitsConsumed,
+        uint nbBits
+    )
+    {
+        nuint value = BIT_lookBits(bitD_bitContainer, bitD_bitsConsumed, nbBits);
+        BIT_skipBits(ref bitD_bitsConsumed, nbBits);
+        return value;
+    }
+
+    /*! BIT_readBitsFast() :
+     *  unsafe version; only works if nbBits >= 1 */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static nuint BIT_readBitsFast(
+        nuint bitD_bitContainer,
+        ref uint bitD_bitsConsumed,
+        uint nbBits
+    )
+    {
+        nuint value = BIT_lookBitsFast(bitD_bitContainer, bitD_bitsConsumed, nbBits);
+        assert(nbBits >= 1);
+        BIT_skipBits(ref bitD_bitsConsumed, 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(
+        ref nuint bitD_bitContainer,
+        ref uint bitD_bitsConsumed,
+        ref sbyte* bitD_ptr,
+        sbyte* bitD_start,
+        sbyte* bitD_limitPtr
+    )
+    {
+        if (bitD_ptr < bitD_limitPtr)
+            return BIT_DStream_status.BIT_DStream_overflow;
+        return BIT_reloadDStream_internal(
+            ref bitD_bitContainer,
+            ref bitD_bitsConsumed,
+            ref bitD_ptr,
+            bitD_start
+        );
+    }
+
+    /*! BIT_reloadDStream() :
+     *  Refill `bitD` from buffer previously set in BIT_initDStream() .
+     *  This function is safe, it guarantees it will not never 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(
+        ref nuint bitD_bitContainer,
+        ref uint bitD_bitsConsumed,
+        ref sbyte* bitD_ptr,
+        sbyte* bitD_start,
+        sbyte* bitD_limitPtr
+    )
+    {
+        if (bitD_bitsConsumed > (uint)(sizeof(nuint) * 8))
+        {
+            bitD_ptr = (sbyte*)&static_zeroFilled[0];
+            return BIT_DStream_status.BIT_DStream_overflow;
+        }
+
+        assert(bitD_ptr >= bitD_start);
+        if (bitD_ptr >= bitD_limitPtr)
+        {
+            return BIT_reloadDStream_internal(
+                ref bitD_bitContainer,
+                ref bitD_bitsConsumed,
+                ref bitD_ptr,
+                bitD_start
+            );
+        }
+
+        if (bitD_ptr == bitD_start)
+        {
+            if (bitD_bitsConsumed < (uint)(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(bitD_ptr);
+            return result;
+        }
+    }
+
+    /*! BIT_reloadDStream_internal() :
+     *  Simple variant of BIT_reloadDStream(), with two conditions:
+     *  1. bitstream is valid : bitsConsumed <= sizeof(bitD->bitContainer)*8
+     *  2. look window is valid after shifted down : bitD->ptr >= bitD->start
+     */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static BIT_DStream_status BIT_reloadDStream_internal(
+        ref nuint bitD_bitContainer,
+        ref uint bitD_bitsConsumed,
+        ref sbyte* bitD_ptr,
+        sbyte* bitD_start
+    )
+    {
+        assert(bitD_bitsConsumed <= (uint)(sizeof(nuint) * 8));
+        bitD_ptr -= bitD_bitsConsumed >> 3;
+        assert(bitD_ptr >= bitD_start);
+        bitD_bitsConsumed &= 7;
+        bitD_bitContainer = MEM_readLEST(bitD_ptr);
+        return BIT_DStream_status.BIT_DStream_unfinished;
+    }
+
+    /*! BIT_endOfDStream() :
+     * @return : 1 if DStream has _exactly_ reached its end (all bits consumed).
+     */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static uint BIT_endOfDStream(
+        uint DStream_bitsConsumed,
+        sbyte* DStream_ptr,
+        sbyte* DStream_start
+    )
+    {
+        return DStream_ptr == DStream_start && DStream_bitsConsumed == (uint)(sizeof(nuint) * 8)
+            ? 1U
+            : 0U;
+    }
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/BlockSummary.cs

@@ -0,0 +1,8 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public struct BlockSummary
+{
+    public nuint nbSequences;
+    public nuint blockSize;
+    public nuint litSize;
+}

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

@@ -0,0 +1,20 @@
+namespace SharpCompress.Compressors.ZStandard.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 struct COVER_best_s
+{
+    public void* mutex;
+    public void* cond;
+    public nuint liveJobs;
+    public void* dict;
+    public nuint dictSize;
+    public ZDICT_cover_params_t parameters;
+    public nuint compressedSize;
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/COVER_ctx_t.cs

@@ -0,0 +1,19 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/*-*************************************
+ * Context
+ ***************************************/
+public unsafe struct COVER_ctx_t
+{
+    public byte* samples;
+    public nuint* offsets;
+    public nuint* samplesSizes;
+    public nuint nbSamples;
+    public nuint nbTrainSamples;
+    public nuint nbTestSamples;
+    public uint* suffix;
+    public nuint suffixSize;
+    public uint* freqs;
+    public uint* dmerAt;
+    public uint d;
+}

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

@@ -0,0 +1,11 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/**
+ * Struct used for the dictionary selection function.
+ */
+public unsafe struct COVER_dictSelection
+{
+    public byte* dictContent;
+    public nuint dictSize;
+    public nuint totalCompressedSize;
+}

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

@@ -0,0 +1,10 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/**
+ *Number of epochs and size of each epoch.
+ */
+public struct COVER_epoch_info_t
+{
+    public uint num;
+    public uint size;
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/COVER_map_pair_t_s.cs

@@ -0,0 +1,7 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public struct COVER_map_pair_t_s
+{
+    public uint key;
+    public uint value;
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/COVER_map_s.cs

@@ -0,0 +1,9 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public unsafe struct COVER_map_s
+{
+    public COVER_map_pair_t_s* data;
+    public uint sizeLog;
+    public uint size;
+    public uint sizeMask;
+}

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

@@ -0,0 +1,11 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/**
+ * A segment is a range in the source as well as the score of the segment.
+ */
+public struct COVER_segment_t
+{
+    public uint begin;
+    public uint end;
+    public uint score;
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/COVER_tryParameters_data_s.cs

@@ -0,0 +1,12 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/**
+ * Parameters for COVER_tryParameters().
+ */
+public unsafe struct COVER_tryParameters_data_s
+{
+    public COVER_ctx_t* ctx;
+    public COVER_best_s* best;
+    public nuint dictBufferCapacity;
+    public ZDICT_cover_params_t parameters;
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/Clevels.cs

@@ -0,0 +1,849 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public static unsafe partial class Methods
+{
+    private static readonly ZSTD_compressionParameters[][] ZSTD_defaultCParameters =
+        new ZSTD_compressionParameters[4][]
+        {
+            new ZSTD_compressionParameters[23]
+            {
+                new ZSTD_compressionParameters(
+                    windowLog: 19,
+                    chainLog: 12,
+                    hashLog: 13,
+                    searchLog: 1,
+                    minMatch: 6,
+                    targetLength: 1,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 19,
+                    chainLog: 13,
+                    hashLog: 14,
+                    searchLog: 1,
+                    minMatch: 7,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 20,
+                    chainLog: 15,
+                    hashLog: 16,
+                    searchLog: 1,
+                    minMatch: 6,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 21,
+                    chainLog: 16,
+                    hashLog: 17,
+                    searchLog: 1,
+                    minMatch: 5,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_dfast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 21,
+                    chainLog: 18,
+                    hashLog: 18,
+                    searchLog: 1,
+                    minMatch: 5,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_dfast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 21,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 3,
+                    minMatch: 5,
+                    targetLength: 2,
+                    strategy: ZSTD_strategy.ZSTD_greedy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 21,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 3,
+                    minMatch: 5,
+                    targetLength: 4,
+                    strategy: ZSTD_strategy.ZSTD_lazy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 21,
+                    chainLog: 19,
+                    hashLog: 20,
+                    searchLog: 4,
+                    minMatch: 5,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 21,
+                    chainLog: 19,
+                    hashLog: 20,
+                    searchLog: 4,
+                    minMatch: 5,
+                    targetLength: 16,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 22,
+                    chainLog: 20,
+                    hashLog: 21,
+                    searchLog: 4,
+                    minMatch: 5,
+                    targetLength: 16,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 22,
+                    chainLog: 21,
+                    hashLog: 22,
+                    searchLog: 5,
+                    minMatch: 5,
+                    targetLength: 16,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 22,
+                    chainLog: 21,
+                    hashLog: 22,
+                    searchLog: 6,
+                    minMatch: 5,
+                    targetLength: 16,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 22,
+                    chainLog: 22,
+                    hashLog: 23,
+                    searchLog: 6,
+                    minMatch: 5,
+                    targetLength: 32,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 22,
+                    chainLog: 22,
+                    hashLog: 22,
+                    searchLog: 4,
+                    minMatch: 5,
+                    targetLength: 32,
+                    strategy: ZSTD_strategy.ZSTD_btlazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 22,
+                    chainLog: 22,
+                    hashLog: 23,
+                    searchLog: 5,
+                    minMatch: 5,
+                    targetLength: 32,
+                    strategy: ZSTD_strategy.ZSTD_btlazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 22,
+                    chainLog: 23,
+                    hashLog: 23,
+                    searchLog: 6,
+                    minMatch: 5,
+                    targetLength: 32,
+                    strategy: ZSTD_strategy.ZSTD_btlazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 22,
+                    chainLog: 22,
+                    hashLog: 22,
+                    searchLog: 5,
+                    minMatch: 5,
+                    targetLength: 48,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 23,
+                    chainLog: 23,
+                    hashLog: 22,
+                    searchLog: 5,
+                    minMatch: 4,
+                    targetLength: 64,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 23,
+                    chainLog: 23,
+                    hashLog: 22,
+                    searchLog: 6,
+                    minMatch: 3,
+                    targetLength: 64,
+                    strategy: ZSTD_strategy.ZSTD_btultra
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 23,
+                    chainLog: 24,
+                    hashLog: 22,
+                    searchLog: 7,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 25,
+                    chainLog: 25,
+                    hashLog: 23,
+                    searchLog: 7,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 26,
+                    chainLog: 26,
+                    hashLog: 24,
+                    searchLog: 7,
+                    minMatch: 3,
+                    targetLength: 512,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 27,
+                    chainLog: 27,
+                    hashLog: 25,
+                    searchLog: 9,
+                    minMatch: 3,
+                    targetLength: 999,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+            },
+            new ZSTD_compressionParameters[23]
+            {
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 12,
+                    hashLog: 13,
+                    searchLog: 1,
+                    minMatch: 5,
+                    targetLength: 1,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 13,
+                    hashLog: 14,
+                    searchLog: 1,
+                    minMatch: 6,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 14,
+                    hashLog: 14,
+                    searchLog: 1,
+                    minMatch: 5,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_dfast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 16,
+                    hashLog: 16,
+                    searchLog: 1,
+                    minMatch: 4,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_dfast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 16,
+                    hashLog: 17,
+                    searchLog: 3,
+                    minMatch: 5,
+                    targetLength: 2,
+                    strategy: ZSTD_strategy.ZSTD_greedy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 17,
+                    hashLog: 18,
+                    searchLog: 5,
+                    minMatch: 5,
+                    targetLength: 2,
+                    strategy: ZSTD_strategy.ZSTD_greedy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 3,
+                    minMatch: 5,
+                    targetLength: 4,
+                    strategy: ZSTD_strategy.ZSTD_lazy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 4,
+                    minMatch: 4,
+                    targetLength: 4,
+                    strategy: ZSTD_strategy.ZSTD_lazy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 4,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 5,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 6,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 5,
+                    minMatch: 4,
+                    targetLength: 12,
+                    strategy: ZSTD_strategy.ZSTD_btlazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 19,
+                    hashLog: 19,
+                    searchLog: 7,
+                    minMatch: 4,
+                    targetLength: 12,
+                    strategy: ZSTD_strategy.ZSTD_btlazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 4,
+                    minMatch: 4,
+                    targetLength: 16,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 4,
+                    minMatch: 3,
+                    targetLength: 32,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 18,
+                    hashLog: 19,
+                    searchLog: 6,
+                    minMatch: 3,
+                    targetLength: 128,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 19,
+                    hashLog: 19,
+                    searchLog: 6,
+                    minMatch: 3,
+                    targetLength: 128,
+                    strategy: ZSTD_strategy.ZSTD_btultra
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 19,
+                    hashLog: 19,
+                    searchLog: 8,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btultra
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 19,
+                    hashLog: 19,
+                    searchLog: 6,
+                    minMatch: 3,
+                    targetLength: 128,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 19,
+                    hashLog: 19,
+                    searchLog: 8,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 19,
+                    hashLog: 19,
+                    searchLog: 10,
+                    minMatch: 3,
+                    targetLength: 512,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 19,
+                    hashLog: 19,
+                    searchLog: 12,
+                    minMatch: 3,
+                    targetLength: 512,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 18,
+                    chainLog: 19,
+                    hashLog: 19,
+                    searchLog: 13,
+                    minMatch: 3,
+                    targetLength: 999,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+            },
+            new ZSTD_compressionParameters[23]
+            {
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 12,
+                    hashLog: 12,
+                    searchLog: 1,
+                    minMatch: 5,
+                    targetLength: 1,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 12,
+                    hashLog: 13,
+                    searchLog: 1,
+                    minMatch: 6,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 13,
+                    hashLog: 15,
+                    searchLog: 1,
+                    minMatch: 5,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 15,
+                    hashLog: 16,
+                    searchLog: 2,
+                    minMatch: 5,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_dfast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 17,
+                    hashLog: 17,
+                    searchLog: 2,
+                    minMatch: 4,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_dfast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 16,
+                    hashLog: 17,
+                    searchLog: 3,
+                    minMatch: 4,
+                    targetLength: 2,
+                    strategy: ZSTD_strategy.ZSTD_greedy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 16,
+                    hashLog: 17,
+                    searchLog: 3,
+                    minMatch: 4,
+                    targetLength: 4,
+                    strategy: ZSTD_strategy.ZSTD_lazy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 16,
+                    hashLog: 17,
+                    searchLog: 3,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 16,
+                    hashLog: 17,
+                    searchLog: 4,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 16,
+                    hashLog: 17,
+                    searchLog: 5,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 16,
+                    hashLog: 17,
+                    searchLog: 6,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 17,
+                    hashLog: 17,
+                    searchLog: 5,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_btlazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 7,
+                    minMatch: 4,
+                    targetLength: 12,
+                    strategy: ZSTD_strategy.ZSTD_btlazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 3,
+                    minMatch: 4,
+                    targetLength: 12,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 4,
+                    minMatch: 3,
+                    targetLength: 32,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 6,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 6,
+                    minMatch: 3,
+                    targetLength: 128,
+                    strategy: ZSTD_strategy.ZSTD_btultra
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 8,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btultra
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 10,
+                    minMatch: 3,
+                    targetLength: 512,
+                    strategy: ZSTD_strategy.ZSTD_btultra
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 5,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 7,
+                    minMatch: 3,
+                    targetLength: 512,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 9,
+                    minMatch: 3,
+                    targetLength: 512,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 17,
+                    chainLog: 18,
+                    hashLog: 17,
+                    searchLog: 11,
+                    minMatch: 3,
+                    targetLength: 999,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+            },
+            new ZSTD_compressionParameters[23]
+            {
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 12,
+                    hashLog: 13,
+                    searchLog: 1,
+                    minMatch: 5,
+                    targetLength: 1,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 14,
+                    hashLog: 15,
+                    searchLog: 1,
+                    minMatch: 5,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 14,
+                    hashLog: 15,
+                    searchLog: 1,
+                    minMatch: 4,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_fast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 14,
+                    hashLog: 15,
+                    searchLog: 2,
+                    minMatch: 4,
+                    targetLength: 0,
+                    strategy: ZSTD_strategy.ZSTD_dfast
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 14,
+                    hashLog: 14,
+                    searchLog: 4,
+                    minMatch: 4,
+                    targetLength: 2,
+                    strategy: ZSTD_strategy.ZSTD_greedy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 14,
+                    hashLog: 14,
+                    searchLog: 3,
+                    minMatch: 4,
+                    targetLength: 4,
+                    strategy: ZSTD_strategy.ZSTD_lazy
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 14,
+                    hashLog: 14,
+                    searchLog: 4,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 14,
+                    hashLog: 14,
+                    searchLog: 6,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 14,
+                    hashLog: 14,
+                    searchLog: 8,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_lazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 14,
+                    searchLog: 5,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_btlazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 14,
+                    searchLog: 9,
+                    minMatch: 4,
+                    targetLength: 8,
+                    strategy: ZSTD_strategy.ZSTD_btlazy2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 14,
+                    searchLog: 3,
+                    minMatch: 4,
+                    targetLength: 12,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 14,
+                    searchLog: 4,
+                    minMatch: 3,
+                    targetLength: 24,
+                    strategy: ZSTD_strategy.ZSTD_btopt
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 14,
+                    searchLog: 5,
+                    minMatch: 3,
+                    targetLength: 32,
+                    strategy: ZSTD_strategy.ZSTD_btultra
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 15,
+                    searchLog: 6,
+                    minMatch: 3,
+                    targetLength: 64,
+                    strategy: ZSTD_strategy.ZSTD_btultra
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 15,
+                    searchLog: 7,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btultra
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 15,
+                    searchLog: 5,
+                    minMatch: 3,
+                    targetLength: 48,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 15,
+                    searchLog: 6,
+                    minMatch: 3,
+                    targetLength: 128,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 15,
+                    searchLog: 7,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 15,
+                    searchLog: 8,
+                    minMatch: 3,
+                    targetLength: 256,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 15,
+                    searchLog: 8,
+                    minMatch: 3,
+                    targetLength: 512,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 15,
+                    searchLog: 9,
+                    minMatch: 3,
+                    targetLength: 512,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+                new ZSTD_compressionParameters(
+                    windowLog: 14,
+                    chainLog: 15,
+                    hashLog: 15,
+                    searchLog: 10,
+                    minMatch: 3,
+                    targetLength: 999,
+                    strategy: ZSTD_strategy.ZSTD_btultra2
+                ),
+            },
+        };
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/Compiler.cs

@@ -0,0 +1,61 @@
+using System.Runtime.CompilerServices;
+
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public static unsafe partial class Methods
+{
+    /* @return 1 if @u is a 2^n value, 0 otherwise
+     * useful to check a value is valid for alignment restrictions */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static int ZSTD_isPower2(nuint u)
+    {
+        return (u & u - 1) == 0 ? 1 : 0;
+    }
+
+    /**
+     * Helper function to perform a wrapped pointer difference without triggering
+     * UBSAN.
+     *
+     * @returns lhs - rhs with wrapping
+     */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static nint ZSTD_wrappedPtrDiff(byte* lhs, byte* rhs)
+    {
+        return (nint)(lhs - rhs);
+    }
+
+    /**
+     * Helper function to perform a wrapped pointer add without triggering UBSAN.
+     *
+     * @return ptr + add with wrapping
+     */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static byte* ZSTD_wrappedPtrAdd(byte* ptr, nint add)
+    {
+        return ptr + add;
+    }
+
+    /**
+     * Helper function to perform a wrapped pointer subtraction without triggering
+     * UBSAN.
+     *
+     * @return ptr - sub with wrapping
+     */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static byte* ZSTD_wrappedPtrSub(byte* ptr, nint sub)
+    {
+        return ptr - sub;
+    }
+
+    /**
+     * Helper function to add to a pointer that works around C's undefined behavior
+     * of adding 0 to NULL.
+     *
+     * @returns `ptr + add` except it defines `NULL + 0 == NULL`.
+     */
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static byte* ZSTD_maybeNullPtrAdd(byte* ptr, nint add)
+    {
+        return add > 0 ? ptr + add : ptr;
+    }
+}

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

@@ -0,0 +1,444 @@
+using static SharpCompress.Compressors.ZStandard.UnsafeHelper;
+
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public static unsafe partial class Methods
+{
+    private static int g_displayLevel = 0;
+
+    /**
+     * Returns the sum of the sample sizes.
+     */
+    private 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.
+     */
+    private static void COVER_warnOnSmallCorpus(nuint maxDictSize, nuint nbDmers, int displayLevel)
+    {
+        double ratio = nbDmers / (double)maxDictSize;
+        if (ratio >= 10)
+        {
+            return;
+        }
+    }
+
+    /**
+     * 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.
+     */
+    private 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 = 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
+     */
+    private 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));
+        /* Pointers */
+        ZSTD_CCtx_s* cctx;
+        ZSTD_CDict_s* cdict;
+        void* dst;
+        /* Local variables */
+        nuint dstCapacity;
+        nuint i;
+        {
+            nuint maxSampleSize = 0;
+            i = parameters.splitPoint < 1 ? 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(dict, dictBufferCapacity, parameters.zParams.compressionLevel);
+        if (dst == null || cctx == null || cdict == null)
+        {
+            goto _compressCleanup;
+        }
+
+        totalCompressedSize = dictBufferCapacity;
+        i = parameters.splitPoint < 1 ? nbTrainSamples : 0;
+        for (; i < nbSamples; ++i)
+        {
+            nuint size = ZSTD_compress_usingCDict(
+                cctx,
+                dst,
+                dstCapacity,
+                samples + offsets[i],
+                samplesSizes[i],
+                cdict
+            );
+            if (ERR_isError(size))
+            {
+                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`.
+     */
+    private static void COVER_best_init(COVER_best_s* best)
+    {
+        if (best == null)
+            return;
+        SynchronizationWrapper.Init(&best->mutex);
+        best->liveJobs = 0;
+        best->dict = null;
+        best->dictSize = 0;
+        best->compressedSize = unchecked((nuint)(-1));
+        best->parameters = new ZDICT_cover_params_t();
+    }
+
+    /**
+     * Wait until liveJobs == 0.
+     */
+    private static void COVER_best_wait(COVER_best_s* best)
+    {
+        if (best == null)
+        {
+            return;
+        }
+
+        SynchronizationWrapper.Enter(&best->mutex);
+        while (best->liveJobs != 0)
+        {
+            SynchronizationWrapper.Wait(&best->mutex);
+        }
+
+        SynchronizationWrapper.Exit(&best->mutex);
+    }
+
+    /**
+     * Call COVER_best_wait() and then destroy the COVER_best_t.
+     */
+    private static void COVER_best_destroy(COVER_best_s* best)
+    {
+        if (best == null)
+        {
+            return;
+        }
+
+        COVER_best_wait(best);
+        if (best->dict != null)
+        {
+            free(best->dict);
+        }
+
+        SynchronizationWrapper.Free(&best->mutex);
+    }
+
+    /**
+     * Called when a thread is about to be launched.
+     * Increments liveJobs.
+     */
+    private static void COVER_best_start(COVER_best_s* best)
+    {
+        if (best == null)
+        {
+            return;
+        }
+
+        SynchronizationWrapper.Enter(&best->mutex);
+        ++best->liveJobs;
+        SynchronizationWrapper.Exit(&best->mutex);
+    }
+
+    /**
+     * 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.
+     */
+    private static void COVER_best_finish(
+        COVER_best_s* best,
+        ZDICT_cover_params_t parameters,
+        COVER_dictSelection selection
+    )
+    {
+        void* dict = selection.dictContent;
+        nuint compressedSize = selection.totalCompressedSize;
+        nuint dictSize = selection.dictSize;
+        if (best == null)
+        {
+            return;
+        }
+
+        {
+            nuint liveJobs;
+            SynchronizationWrapper.Enter(&best->mutex);
+            --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;
+                        SynchronizationWrapper.Pulse(&best->mutex);
+                        SynchronizationWrapper.Exit(&best->mutex);
+                        return;
+                    }
+                }
+
+                if (dict != null)
+                {
+                    memcpy(best->dict, dict, (uint)dictSize);
+                    best->dictSize = dictSize;
+                    best->parameters = parameters;
+                    best->compressedSize = compressedSize;
+                }
+            }
+
+            if (liveJobs == 0)
+            {
+                SynchronizationWrapper.PulseAll(&best->mutex);
+            }
+
+            SynchronizationWrapper.Exit(&best->mutex);
+        }
+    }
+
+    private static COVER_dictSelection setDictSelection(byte* buf, nuint s, nuint csz)
+    {
+        COVER_dictSelection ds;
+        ds.dictContent = buf;
+        ds.dictSize = s;
+        ds.totalCompressedSize = csz;
+        return ds;
+    }
+
+    /**
+     * Error function for COVER_selectDict function. Returns a struct where
+     * return.totalCompressedSize is a ZSTD error.
+     */
+    private static COVER_dictSelection COVER_dictSelectionError(nuint error)
+    {
+        return setDictSelection(null, 0, error);
+    }
+
+    /**
+     * Error function for COVER_selectDict function. Checks if the return
+     * value is an error.
+     */
+    private static uint COVER_dictSelectionIsError(COVER_dictSelection selection)
+    {
+        return ERR_isError(selection.totalCompressedSize) || selection.dictContent == null
+            ? 1U
+            : 0U;
+    }
+
+    /**
+     * Always call after selectDict is called to free up used memory from
+     * newly created dictionary.
+     */
+    private static void COVER_dictSelectionFree(COVER_dictSelection selection)
+    {
+        free(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.
+     */
+    private 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 + 1;
+        if (largestDictbuffer == null || candidateDictBuffer == null)
+        {
+            free(largestDictbuffer);
+            free(candidateDictBuffer);
+            return COVER_dictSelectionError(dictContentSize);
+        }
+
+        memcpy(largestDictbuffer, customDictContent, (uint)dictContentSize);
+        dictContentSize = ZDICT_finalizeDictionary(
+            largestDictbuffer,
+            dictBufferCapacity,
+            customDictContent,
+            dictContentSize,
+            samplesBuffer,
+            samplesSizes,
+            nbFinalizeSamples,
+            @params.zParams
+        );
+        if (ZDICT_isError(dictContentSize))
+        {
+            free(largestDictbuffer);
+            free(candidateDictBuffer);
+            return COVER_dictSelectionError(dictContentSize);
+        }
+
+        totalCompressedSize = COVER_checkTotalCompressedSize(
+            @params,
+            samplesSizes,
+            samplesBuffer,
+            offsets,
+            nbCheckSamples,
+            nbSamples,
+            largestDictbuffer,
+            dictContentSize
+        );
+        if (ERR_isError(totalCompressedSize))
+        {
+            free(largestDictbuffer);
+            free(candidateDictBuffer);
+            return COVER_dictSelectionError(totalCompressedSize);
+        }
+
+        if (@params.shrinkDict == 0)
+        {
+            free(candidateDictBuffer);
+            return setDictSelection(largestDictbuffer, dictContentSize, totalCompressedSize);
+        }
+
+        largestDict = dictContentSize;
+        largestCompressed = totalCompressedSize;
+        dictContentSize = 256;
+        while (dictContentSize < largestDict)
+        {
+            memcpy(candidateDictBuffer, largestDictbuffer, (uint)largestDict);
+            dictContentSize = ZDICT_finalizeDictionary(
+                candidateDictBuffer,
+                dictBufferCapacity,
+                customDictContentEnd - dictContentSize,
+                dictContentSize,
+                samplesBuffer,
+                samplesSizes,
+                nbFinalizeSamples,
+                @params.zParams
+            );
+            if (ZDICT_isError(dictContentSize))
+            {
+                free(largestDictbuffer);
+                free(candidateDictBuffer);
+                return COVER_dictSelectionError(dictContentSize);
+            }
+
+            totalCompressedSize = COVER_checkTotalCompressedSize(
+                @params,
+                samplesSizes,
+                samplesBuffer,
+                offsets,
+                nbCheckSamples,
+                nbSamples,
+                candidateDictBuffer,
+                dictContentSize
+            );
+            if (ERR_isError(totalCompressedSize))
+            {
+                free(largestDictbuffer);
+                free(candidateDictBuffer);
+                return COVER_dictSelectionError(totalCompressedSize);
+            }
+
+            if (totalCompressedSize <= largestCompressed * regressionTolerance)
+            {
+                free(largestDictbuffer);
+                return setDictSelection(candidateDictBuffer, dictContentSize, totalCompressedSize);
+            }
+
+            dictContentSize *= 2;
+        }
+
+        dictContentSize = largestDict;
+        totalCompressedSize = largestCompressed;
+        free(candidateDictBuffer);
+        return setDictSelection(largestDictbuffer, dictContentSize, totalCompressedSize);
+    }
+}

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

@@ -0,0 +1,12 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/*-***************************/
+/*  generic DTableDesc       */
+/*-***************************/
+public struct DTableDesc
+{
+    public byte maxTableLog;
+    public byte tableType;
+    public byte tableLog;
+    public byte reserved;
+}

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

@@ -0,0 +1,13 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public unsafe 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/ZStandard/Unsafe/EntropyCommon.cs

@@ -0,0 +1,447 @@
+using System.Runtime.CompilerServices;
+using static SharpCompress.Compressors.ZStandard.UnsafeHelper;
+
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public static unsafe partial class Methods
+{
+    /*===   Version   ===*/
+    private static uint FSE_versionNumber()
+    {
+        return 0 * 100 * 100 + 9 * 100 + 0;
+    }
+
+    /*===   Error Management   ===*/
+    private static bool FSE_isError(nuint code)
+    {
+        return ERR_isError(code);
+    }
+
+    private static string FSE_getErrorName(nuint code)
+    {
+        return ERR_getErrorName(code);
+    }
+
+    /* Error Management */
+    private static bool HUF_isError(nuint code)
+    {
+        return ERR_isError(code);
+    }
+
+    private static string HUF_getErrorName(nuint code)
+    {
+        return ERR_getErrorName(code);
+    }
+
+    /*-**************************************************************
+     *  FSE NCount encoding-decoding
+     ****************************************************************/
+    [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];
+            /* This function only works when hbSize >= 8 */
+            memset(buffer, 0, sizeof(sbyte) * 8);
+            memcpy(buffer, headerBuffer, (uint)hbSize);
+            {
+                nuint countSize = FSE_readNCount(
+                    normalizedCounter,
+                    maxSVPtr,
+                    tableLogPtr,
+                    buffer,
+                    sizeof(sbyte) * 8
+                );
+                if (FSE_isError(countSize))
+                    return countSize;
+                if (countSize > hbSize)
+                    return unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected));
+                return countSize;
+            }
+        }
+
+        assert(hbSize >= 8);
+        memset(normalizedCounter, 0, (*maxSVPtr + 1) * sizeof(short));
+        bitStream = MEM_readLE32(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)
+            {
+                /* Count the number of repeats. Each time the
+                 * 2-bit repeat code is 0b11 there is another
+                 * repeat.
+                 * Avoid UB by setting the high bit to 1.
+                 */
+                int repeats = (int)(ZSTD_countTrailingZeros32(~bitStream | 0x80000000) >> 1);
+                while (repeats >= 12)
+                {
+                    charnum += 3 * 12;
+                    if (ip <= iend - 7)
+                    {
+                        ip += 3;
+                    }
+                    else
+                    {
+                        bitCount -= (int)(8 * (iend - 7 - ip));
+                        bitCount &= 31;
+                        ip = iend - 4;
+                    }
+
+                    bitStream = MEM_readLE32(ip) >> bitCount;
+                    repeats = (int)(ZSTD_countTrailingZeros32(~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(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)(ZSTD_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(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);
+    }
+
+    /*! FSE_readNCount_bmi2():
+     * Same as FSE_readNCount() but pass bmi2=1 when your CPU supports BMI2 and 0 otherwise.
+     */
+    private static nuint FSE_readNCount_bmi2(
+        short* normalizedCounter,
+        uint* maxSVPtr,
+        uint* tableLogPtr,
+        void* headerBuffer,
+        nuint hbSize,
+        int bmi2
+    )
+    {
+        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 */
+    private 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?() .
+     */
+    private static nuint HUF_readStats(
+        byte* huffWeight,
+        nuint hwSize,
+        uint* rankStats,
+        uint* nbSymbolsPtr,
+        uint* tableLogPtr,
+        void* src,
+        nuint srcSize
+    )
+    {
+        uint* wksp = stackalloc uint[219];
+        return HUF_readStats_wksp(
+            huffWeight,
+            hwSize,
+            rankStats,
+            nbSymbolsPtr,
+            tableLogPtr,
+            src,
+            srcSize,
+            wksp,
+            sizeof(uint) * 219,
+            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(
+                huffWeight,
+                hwSize - 1,
+                ip + 1,
+                iSize,
+                6,
+                workSpace,
+                wkspSize,
+                bmi2
+            );
+            if (FSE_isError(oSize))
+                return oSize;
+        }
+
+        memset(rankStats, 0, (12 + 1) * 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 << huffWeight[n] >> 1);
+            }
+        }
+
+        if (weightTotal == 0)
+            return unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_corruption_detected));
+        {
+            uint tableLog = ZSTD_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)ZSTD_highbit32(rest));
+                uint lastWeight = ZSTD_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_wksp(
+        byte* huffWeight,
+        nuint hwSize,
+        uint* rankStats,
+        uint* nbSymbolsPtr,
+        uint* tableLogPtr,
+        void* src,
+        nuint srcSize,
+        void* workSpace,
+        nuint wkspSize,
+        int flags
+    )
+    {
+        return HUF_readStats_body_default(
+            huffWeight,
+            hwSize,
+            rankStats,
+            nbSymbolsPtr,
+            tableLogPtr,
+            src,
+            srcSize,
+            workSpace,
+            wkspSize
+        );
+    }
+}

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

@@ -0,0 +1,110 @@
+using System.Runtime.CompilerServices;
+
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public static unsafe partial class Methods
+{
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static bool ERR_isError(nuint code)
+    {
+        return code > unchecked((nuint)(-(int)ZSTD_ErrorCode.ZSTD_error_maxCode));
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static ZSTD_ErrorCode ERR_getErrorCode(nuint code)
+    {
+        if (!ERR_isError(code))
+            return 0;
+        return (ZSTD_ErrorCode)(0 - code);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static string ERR_getErrorName(nuint code)
+    {
+        return ERR_getErrorString(ERR_getErrorCode(code));
+    }
+
+    /*-****************************************
+     *  Error Strings
+     ******************************************/
+    private static string ERR_getErrorString(ZSTD_ErrorCode code)
+    {
+        const string 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 "Data corruption detected";
+            case ZSTD_ErrorCode.ZSTD_error_checksum_wrong:
+                return "Restored data doesn't match checksum";
+            case ZSTD_ErrorCode.ZSTD_error_literals_headerWrong:
+                return "Header of Literals' block doesn't respect format specification";
+            case ZSTD_ErrorCode.ZSTD_error_parameter_unsupported:
+                return "Unsupported parameter";
+            case ZSTD_ErrorCode.ZSTD_error_parameter_combination_unsupported:
+                return "Unsupported combination of parameters";
+            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_cannotProduce_uncompressedBlock:
+                return "This mode cannot generate an uncompressed block";
+            case ZSTD_ErrorCode.ZSTD_error_stabilityCondition_notRespected:
+                return "pledged buffer stability condition is not respected";
+            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_noForwardProgress_destFull:
+                return "Operation made no progress over multiple calls, due to output buffer being full";
+            case ZSTD_ErrorCode.ZSTD_error_noForwardProgress_inputEmpty:
+                return "Operation made no progress over multiple calls, due to input being empty";
+            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_sequenceProducer_failed:
+                return "Block-level external sequence producer returned an error code";
+            case ZSTD_ErrorCode.ZSTD_error_externalSequences_invalid:
+                return "External sequences are not valid";
+            case ZSTD_ErrorCode.ZSTD_error_maxCode:
+            default:
+                return notErrorCode;
+        }
+    }
+}

src/SharpCompress/Compressors/ZStandard/Unsafe/EstimatedBlockSize.cs

@@ -0,0 +1,7 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public struct EstimatedBlockSize
+{
+    public nuint estLitSize;
+    public nuint estBlockSize;
+}

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

@@ -0,0 +1,19 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/*-*************************************
+ * Acceleration
+ ***************************************/
+public 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;
+
+    public FASTCOVER_accel_t(uint finalize, uint skip)
+    {
+        this.finalize = finalize;
+        this.skip = skip;
+    }
+}

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

@@ -0,0 +1,19 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/*-*************************************
+ * Context
+ ***************************************/
+public unsafe 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/ZStandard/Unsafe/FASTCOVER_tryParameters_data_s.cs

@@ -0,0 +1,12 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/**
+ * Parameters for FASTCOVER_tryParameters().
+ */
+public unsafe 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/ZStandard/Unsafe/FPStats.cs

@@ -0,0 +1,7 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+public struct FPStats
+{
+    public Fingerprint pastEvents;
+    public Fingerprint newEvents;
+}

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

@@ -0,0 +1,16 @@
+namespace SharpCompress.Compressors.ZStandard.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 struct FSE_CState_t
+{
+    public nint value;
+    public void* stateTable;
+    public void* symbolTT;
+    public uint stateLog;
+}

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

@@ -0,0 +1,12 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/* *****************************************
+ *  FSE symbol decompression API
+ *******************************************/
+public unsafe struct FSE_DState_t
+{
+    public nuint state;
+
+    /* precise table may vary, depending on U16 */
+    public void* table;
+}

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

@@ -0,0 +1,8 @@
+namespace SharpCompress.Compressors.ZStandard.Unsafe;
+
+/* ======    Decompression    ====== */
+public struct FSE_DTableHeader
+{
+    public ushort tableLog;
+    public ushort fastMode;
+}