Mark for 0.31

Update Adler32 from ImageSharp v2.1.0

src/SharpCompress/Algorithms/Adler32.cs

@@ -0,0 +1,420 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
+#define SUPPORTS_RUNTIME_INTRINSICS
+#define SUPPORTS_HOTPATH
+#endif
+
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+#if SUPPORTS_RUNTIME_INTRINSICS
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
+#endif
+
+#pragma warning disable IDE0007 // Use implicit type
+namespace SharpCompress.Algorithms
+{
+    /// <summary>
+    /// Calculates the 32 bit Adler checksum of a given buffer according to
+    /// RFC 1950. ZLIB Compressed Data Format Specification version 3.3)
+    /// </summary>
+    internal static class Adler32 // From https://github.com/SixLabors/ImageSharp/blob/main/src/ImageSharp/Compression/Zlib/Adler32.cs
+    {
+        /// <summary>
+        /// Global inlining options. Helps temporarily disable inlining for better profiler output.
+        /// </summary>
+        private static class InliningOptions // From https://github.com/SixLabors/ImageSharp/blob/main/src/ImageSharp/Common/Helpers/InliningOptions.cs
+        {
+            /// <summary>
+            /// <see cref="MethodImplOptions.AggressiveInlining"/> regardless of the build conditions.
+            /// </summary>
+            public const MethodImplOptions AlwaysInline = MethodImplOptions.AggressiveInlining;
+#if PROFILING
+            public const MethodImplOptions HotPath = MethodImplOptions.NoInlining;
+            public const MethodImplOptions ShortMethod = MethodImplOptions.NoInlining;
+#else
+#if SUPPORTS_HOTPATH
+            public const MethodImplOptions HotPath = MethodImplOptions.AggressiveOptimization;
+#else
+            public const MethodImplOptions HotPath = MethodImplOptions.AggressiveInlining;
+#endif
+            public const MethodImplOptions ShortMethod = MethodImplOptions.AggressiveInlining;
+#endif
+            public const MethodImplOptions ColdPath = MethodImplOptions.NoInlining;
+        }
+
+#if SUPPORTS_RUNTIME_INTRINSICS
+        /// <summary>
+        /// Provides optimized static methods for trigonometric, logarithmic,
+        /// and other common mathematical functions.
+        /// </summary>
+        private static class Numerics // From https://github.com/SixLabors/ImageSharp/blob/main/src/ImageSharp/Common/Helpers/Numerics.cs
+        {
+            /// <summary>
+            /// Reduces elements of the vector into one sum.
+            /// </summary>
+            /// <param name="accumulator">The accumulator to reduce.</param>
+            /// <returns>The sum of all elements.</returns>
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            public static int ReduceSum(Vector256<int> accumulator)
+            {
+                // Add upper lane to lower lane.
+                Vector128<int> vsum = Sse2.Add(accumulator.GetLower(), accumulator.GetUpper());
+
+                // Add odd to even.
+                vsum = Sse2.Add(vsum, Sse2.Shuffle(vsum, 0b_11_11_01_01));
+
+                // Add high to low.
+                vsum = Sse2.Add(vsum, Sse2.Shuffle(vsum, 0b_11_10_11_10));
+
+                return Sse2.ConvertToInt32(vsum);
+            }
+
+            /// <summary>
+            /// Reduces even elements of the vector into one sum.
+            /// </summary>
+            /// <param name="accumulator">The accumulator to reduce.</param>
+            /// <returns>The sum of even elements.</returns>
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            public static int EvenReduceSum(Vector256<int> accumulator)
+            {
+                Vector128<int> vsum = Sse2.Add(accumulator.GetLower(), accumulator.GetUpper()); // add upper lane to lower lane
+                vsum = Sse2.Add(vsum, Sse2.Shuffle(vsum, 0b_11_10_11_10));                      // add high to low
+
+                // Vector128<int>.ToScalar() isn't optimized pre-net5.0 https://github.com/dotnet/runtime/pull/37882
+                return Sse2.ConvertToInt32(vsum);
+            }
+        }
+#endif
+
+        /// <summary>
+        /// The default initial seed value of a Adler32 checksum calculation.
+        /// </summary>
+        public const uint SeedValue = 1U;
+
+        // Largest prime smaller than 65536
+        private const uint BASE = 65521;
+
+        // NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1
+        private const uint NMAX = 5552;
+
+#if SUPPORTS_RUNTIME_INTRINSICS
+        private const int MinBufferSize = 64;
+
+        private const int BlockSize = 1 << 5;
+
+        // The C# compiler emits this as a compile-time constant embedded in the PE file.
+        private static ReadOnlySpan<byte> Tap1Tap2 => new byte[]
+        {
+            32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, // tap1
+            16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 // tap2
+        };
+#endif
+
+        /// <summary>
+        /// Calculates the Adler32 checksum with the bytes taken from the span.
+        /// </summary>
+        /// <param name="buffer">The readonly span of bytes.</param>
+        /// <returns>The <see cref="uint"/>.</returns>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public static uint Calculate(ReadOnlySpan<byte> buffer)
+            => Calculate(SeedValue, buffer);
+
+        /// <summary>
+        /// Calculates the Adler32 checksum with the bytes taken from the span and seed.
+        /// </summary>
+        /// <param name="adler">The input Adler32 value.</param>
+        /// <param name="buffer">The readonly span of bytes.</param>
+        /// <returns>The <see cref="uint"/>.</returns>
+        [MethodImpl(InliningOptions.HotPath | InliningOptions.ShortMethod)]
+        public static uint Calculate(uint adler, ReadOnlySpan<byte> buffer)
+        {
+            if (buffer.IsEmpty)
+            {
+                return adler;
+            }
+
+#if SUPPORTS_RUNTIME_INTRINSICS
+            if (Avx2.IsSupported && buffer.Length >= MinBufferSize)
+            {
+                return CalculateAvx2(adler, buffer);
+            }
+
+            if (Ssse3.IsSupported && buffer.Length >= MinBufferSize)
+            {
+                return CalculateSse(adler, buffer);
+            }
+
+            return CalculateScalar(adler, buffer);
+#else
+            return CalculateScalar(adler, buffer);
+#endif
+        }
+
+        // Based on https://github.com/chromium/chromium/blob/master/third_party/zlib/adler32_simd.c
+#if SUPPORTS_RUNTIME_INTRINSICS
+        [MethodImpl(InliningOptions.HotPath | InliningOptions.ShortMethod)]
+        private static unsafe uint CalculateSse(uint adler, ReadOnlySpan<byte> buffer)
+        {
+            uint s1 = adler & 0xFFFF;
+            uint s2 = (adler >> 16) & 0xFFFF;
+
+            // Process the data in blocks.
+            uint length = (uint)buffer.Length;
+            uint blocks = length / BlockSize;
+            length -= blocks * BlockSize;
+
+            fixed (byte* bufferPtr = &MemoryMarshal.GetReference(buffer))
+            {
+                fixed (byte* tapPtr = &MemoryMarshal.GetReference(Tap1Tap2))
+                {
+                    byte* localBufferPtr = bufferPtr;
+
+                    // _mm_setr_epi8 on x86
+                    Vector128<sbyte> tap1 = Sse2.LoadVector128((sbyte*)tapPtr);
+                    Vector128<sbyte> tap2 = Sse2.LoadVector128((sbyte*)(tapPtr + 0x10));
+                    Vector128<byte> zero = Vector128<byte>.Zero;
+                    var ones = Vector128.Create((short)1);
+
+                    while (blocks > 0)
+                    {
+                        uint n = NMAX / BlockSize;  /* The NMAX constraint. */
+                        if (n > blocks)
+                        {
+                            n = blocks;
+                        }
+
+                        blocks -= n;
+
+                        // Process n blocks of data. At most NMAX data bytes can be
+                        // processed before s2 must be reduced modulo BASE.
+                        Vector128<uint> v_ps = Vector128.CreateScalar(s1 * n);
+                        Vector128<uint> v_s2 = Vector128.CreateScalar(s2);
+                        Vector128<uint> v_s1 = Vector128<uint>.Zero;
+
+                        do
+                        {
+                            // Load 32 input bytes.
+                            Vector128<byte> bytes1 = Sse3.LoadDquVector128(localBufferPtr);
+                            Vector128<byte> bytes2 = Sse3.LoadDquVector128(localBufferPtr + 0x10);
+
+                            // Add previous block byte sum to v_ps.
+                            v_ps = Sse2.Add(v_ps, v_s1);
+
+                            // Horizontally add the bytes for s1, multiply-adds the
+                            // bytes by [ 32, 31, 30, ... ] for s2.
+                            v_s1 = Sse2.Add(v_s1, Sse2.SumAbsoluteDifferences(bytes1, zero).AsUInt32());
+                            Vector128<short> mad1 = Ssse3.MultiplyAddAdjacent(bytes1, tap1);
+                            v_s2 = Sse2.Add(v_s2, Sse2.MultiplyAddAdjacent(mad1, ones).AsUInt32());
+
+                            v_s1 = Sse2.Add(v_s1, Sse2.SumAbsoluteDifferences(bytes2, zero).AsUInt32());
+                            Vector128<short> mad2 = Ssse3.MultiplyAddAdjacent(bytes2, tap2);
+                            v_s2 = Sse2.Add(v_s2, Sse2.MultiplyAddAdjacent(mad2, ones).AsUInt32());
+
+                            localBufferPtr += BlockSize;
+                        }
+                        while (--n > 0);
+
+                        v_s2 = Sse2.Add(v_s2, Sse2.ShiftLeftLogical(v_ps, 5));
+
+                        // Sum epi32 ints v_s1(s2) and accumulate in s1(s2).
+                        const byte S2301 = 0b1011_0001;  // A B C D -> B A D C
+                        const byte S1032 = 0b0100_1110;  // A B C D -> C D A B
+
+                        v_s1 = Sse2.Add(v_s1, Sse2.Shuffle(v_s1, S1032));
+
+                        s1 += v_s1.ToScalar();
+
+                        v_s2 = Sse2.Add(v_s2, Sse2.Shuffle(v_s2, S2301));
+                        v_s2 = Sse2.Add(v_s2, Sse2.Shuffle(v_s2, S1032));
+
+                        s2 = v_s2.ToScalar();
+
+                        // Reduce.
+                        s1 %= BASE;
+                        s2 %= BASE;
+                    }
+
+                    if (length > 0)
+                    {
+                        HandleLeftOver(localBufferPtr, length, ref s1, ref s2);
+                    }
+
+                    return s1 | (s2 << 16);
+                }
+            }
+        }
+
+        // Based on: https://github.com/zlib-ng/zlib-ng/blob/develop/arch/x86/adler32_avx2.c
+        [MethodImpl(InliningOptions.HotPath | InliningOptions.ShortMethod)]
+        public static unsafe uint CalculateAvx2(uint adler, ReadOnlySpan<byte> buffer)
+        {
+            uint s1 = adler & 0xFFFF;
+            uint s2 = (adler >> 16) & 0xFFFF;
+            uint length = (uint)buffer.Length;
+
+            fixed (byte* bufferPtr = &MemoryMarshal.GetReference(buffer))
+            {
+                byte* localBufferPtr = bufferPtr;
+
+                Vector256<byte> zero = Vector256<byte>.Zero;
+                var dot3v = Vector256.Create((short)1);
+                var dot2v = Vector256.Create(32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1);
+
+                // Process n blocks of data. At most NMAX data bytes can be
+                // processed before s2 must be reduced modulo BASE.
+                var vs1 = Vector256.CreateScalar(s1);
+                var vs2 = Vector256.CreateScalar(s2);
+
+                while (length >= 32)
+                {
+                    int k = length < NMAX ? (int)length : (int)NMAX;
+                    k -= k % 32;
+                    length -= (uint)k;
+
+                    Vector256<uint> vs10 = vs1;
+                    Vector256<uint> vs3 = Vector256<uint>.Zero;
+
+                    while (k >= 32)
+                    {
+                        // Load 32 input bytes.
+                        Vector256<byte> block = Avx.LoadVector256(localBufferPtr);
+
+                        // Sum of abs diff, resulting in 2 x int32's
+                        Vector256<ushort> vs1sad = Avx2.SumAbsoluteDifferences(block, zero);
+
+                        vs1 = Avx2.Add(vs1, vs1sad.AsUInt32());
+                        vs3 = Avx2.Add(vs3, vs10);
+
+                        // sum 32 uint8s to 16 shorts.
+                        Vector256<short> vshortsum2 = Avx2.MultiplyAddAdjacent(block, dot2v);
+
+                        // sum 16 shorts to 8 uint32s.
+                        Vector256<int> vsum2 = Avx2.MultiplyAddAdjacent(vshortsum2, dot3v);
+
+                        vs2 = Avx2.Add(vsum2.AsUInt32(), vs2);
+                        vs10 = vs1;
+
+                        localBufferPtr += BlockSize;
+                        k -= 32;
+                    }
+
+                    // Defer the multiplication with 32 to outside of the loop.
+                    vs3 = Avx2.ShiftLeftLogical(vs3, 5);
+                    vs2 = Avx2.Add(vs2, vs3);
+
+                    s1 = (uint)Numerics.EvenReduceSum(vs1.AsInt32());
+                    s2 = (uint)Numerics.ReduceSum(vs2.AsInt32());
+
+                    s1 %= BASE;
+                    s2 %= BASE;
+
+                    vs1 = Vector256.CreateScalar(s1);
+                    vs2 = Vector256.CreateScalar(s2);
+                }
+
+                if (length > 0)
+                {
+                    HandleLeftOver(localBufferPtr, length, ref s1, ref s2);
+                }
+
+                return s1 | (s2 << 16);
+            }
+        }
+
+        private static unsafe void HandleLeftOver(byte* localBufferPtr, uint length, ref uint s1, ref uint s2)
+        {
+            if (length >= 16)
+            {
+                s2 += s1 += localBufferPtr[0];
+                s2 += s1 += localBufferPtr[1];
+                s2 += s1 += localBufferPtr[2];
+                s2 += s1 += localBufferPtr[3];
+                s2 += s1 += localBufferPtr[4];
+                s2 += s1 += localBufferPtr[5];
+                s2 += s1 += localBufferPtr[6];
+                s2 += s1 += localBufferPtr[7];
+                s2 += s1 += localBufferPtr[8];
+                s2 += s1 += localBufferPtr[9];
+                s2 += s1 += localBufferPtr[10];
+                s2 += s1 += localBufferPtr[11];
+                s2 += s1 += localBufferPtr[12];
+                s2 += s1 += localBufferPtr[13];
+                s2 += s1 += localBufferPtr[14];
+                s2 += s1 += localBufferPtr[15];
+
+                localBufferPtr += 16;
+                length -= 16;
+            }
+
+            while (length-- > 0)
+            {
+                s2 += s1 += *localBufferPtr++;
+            }
+
+            if (s1 >= BASE)
+            {
+                s1 -= BASE;
+            }
+
+            s2 %= BASE;
+        }
+#endif
+
+        [MethodImpl(InliningOptions.HotPath | InliningOptions.ShortMethod)]
+        private static unsafe uint CalculateScalar(uint adler, ReadOnlySpan<byte> buffer)
+        {
+            uint s1 = adler & 0xFFFF;
+            uint s2 = (adler >> 16) & 0xFFFF;
+            uint k;
+
+            fixed (byte* bufferPtr = buffer)
+            {
+                var localBufferPtr = bufferPtr;
+                uint length = (uint)buffer.Length;
+
+                while (length > 0)
+                {
+                    k = length < NMAX ? length : NMAX;
+                    length -= k;
+
+                    while (k >= 16)
+                    {
+                        s2 += s1 += localBufferPtr[0];
+                        s2 += s1 += localBufferPtr[1];
+                        s2 += s1 += localBufferPtr[2];
+                        s2 += s1 += localBufferPtr[3];
+                        s2 += s1 += localBufferPtr[4];
+                        s2 += s1 += localBufferPtr[5];
+                        s2 += s1 += localBufferPtr[6];
+                        s2 += s1 += localBufferPtr[7];
+                        s2 += s1 += localBufferPtr[8];
+                        s2 += s1 += localBufferPtr[9];
+                        s2 += s1 += localBufferPtr[10];
+                        s2 += s1 += localBufferPtr[11];
+                        s2 += s1 += localBufferPtr[12];
+                        s2 += s1 += localBufferPtr[13];
+                        s2 += s1 += localBufferPtr[14];
+                        s2 += s1 += localBufferPtr[15];
+
+                        localBufferPtr += 16;
+                        k -= 16;
+                    }
+
+                    while (k-- > 0)
+                    {
+                        s2 += s1 += *localBufferPtr++;
+                    }
+
+                    s1 %= BASE;
+                    s2 %= BASE;
+                }
+
+                return (s2 << 16) | s1;
+            }
+        }
+    }
+}

src/SharpCompress/Algorithms/Alder32.cs

@@ -1,280 +0,0 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the GNU Affero General Public License, Version 3.
-
-using System;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
-using System.Runtime.Intrinsics;
-using System.Runtime.Intrinsics.X86;
-#endif
-
-namespace SharpCompress.Algorithms
-{
-    /// <summary>
-    /// Calculates the 32 bit Adler checksum of a given buffer according to
-    /// RFC 1950. ZLIB Compressed Data Format Specification version 3.3)
-    /// </summary>
-    internal static class Adler32
-    {
-        /// <summary>
-        /// The default initial seed value of a Adler32 checksum calculation.
-        /// </summary>
-        public const uint SeedValue = 1U;
-
-#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
-        private const int MinBufferSize = 64;
-#endif
-
-        // Largest prime smaller than 65536
-        private const uint BASE = 65521;
-
-        // NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1
-        private const uint NMAX = 5552;
-
-        /// <summary>
-        /// Calculates the Adler32 checksum with the bytes taken from the span.
-        /// </summary>
-        /// <param name="buffer">The readonly span of bytes.</param>
-        /// <returns>The <see cref="uint"/>.</returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static uint Calculate(ReadOnlySpan<byte> buffer)
-        {
-            return Calculate(SeedValue, buffer);
-        }
-
-        /// <summary>
-        /// Calculates the Adler32 checksum with the bytes taken from the span and seed.
-        /// </summary>
-        /// <param name="adler">The input Adler32 value.</param>
-        /// <param name="buffer">The readonly span of bytes.</param>
-        /// <returns>The <see cref="uint"/>.</returns>
-        public static uint Calculate(uint adler, ReadOnlySpan<byte> buffer)
-        {
-#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
-            if (Sse3.IsSupported && buffer.Length >= MinBufferSize)
-            {
-                return CalculateSse(adler, buffer);
-            }
-
-            return CalculateScalar(adler, buffer);
-#else
-            return CalculateScalar(adler, buffer);
-#endif
-        }
-
-        // Based on https://github.com/chromium/chromium/blob/master/third_party/zlib/adler32_simd.c
-#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
-        private static unsafe uint CalculateSse(uint adler, ReadOnlySpan<byte> buffer)
-        {
-            uint s1 = adler & 0xFFFF;
-            uint s2 = (adler >> 16) & 0xFFFF;
-
-            // Process the data in blocks.
-            const int BLOCK_SIZE = 1 << 5;
-
-            uint length = (uint)buffer.Length;
-            uint blocks = length / BLOCK_SIZE;
-            length -= blocks * BLOCK_SIZE;
-
-            int index = 0;
-            fixed (byte* bufferPtr = &buffer[0])
-            {
-                index += (int)blocks * BLOCK_SIZE;
-                var localBufferPtr = bufferPtr;
-
-                // _mm_setr_epi8 on x86
-                var tap1 = Vector128.Create(32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17);
-                var tap2 = Vector128.Create(16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1);
-                Vector128<byte> zero = Vector128<byte>.Zero;
-                var ones = Vector128.Create((short)1);
-
-                while (blocks > 0)
-                {
-                    uint n = NMAX / BLOCK_SIZE;  /* The NMAX constraint. */
-                    if (n > blocks)
-                    {
-                        n = blocks;
-                    }
-
-                    blocks -= n;
-
-                    // Process n blocks of data. At most NMAX data bytes can be
-                    // processed before s2 must be reduced modulo BASE.
-                    Vector128<int> v_ps = Vector128.CreateScalar(s1 * n).AsInt32();
-                    Vector128<int> v_s2 = Vector128.CreateScalar(s2).AsInt32();
-                    Vector128<int> v_s1 = Vector128<int>.Zero;
-
-                    do
-                    {
-                        // Load 32 input bytes.
-                        Vector128<byte> bytes1 = Sse3.LoadDquVector128(localBufferPtr);
-                        Vector128<byte> bytes2 = Sse3.LoadDquVector128(localBufferPtr + 16);
-
-                        // Add previous block byte sum to v_ps.
-                        v_ps = Sse2.Add(v_ps, v_s1);
-
-                        // Horizontally add the bytes for s1, multiply-adds the
-                        // bytes by [ 32, 31, 30, ... ] for s2.
-                        v_s1 = Sse2.Add(v_s1, Sse2.SumAbsoluteDifferences(bytes1, zero).AsInt32());
-                        Vector128<short> mad1 = Ssse3.MultiplyAddAdjacent(bytes1, tap1);
-                        v_s2 = Sse2.Add(v_s2, Sse2.MultiplyAddAdjacent(mad1, ones));
-
-                        v_s1 = Sse2.Add(v_s1, Sse2.SumAbsoluteDifferences(bytes2, zero).AsInt32());
-                        Vector128<short> mad2 = Ssse3.MultiplyAddAdjacent(bytes2, tap2);
-                        v_s2 = Sse2.Add(v_s2, Sse2.MultiplyAddAdjacent(mad2, ones));
-
-                        localBufferPtr += BLOCK_SIZE;
-                    }
-                    while (--n > 0);
-
-                    v_s2 = Sse2.Add(v_s2, Sse2.ShiftLeftLogical(v_ps, 5));
-
-                    // Sum epi32 ints v_s1(s2) and accumulate in s1(s2).
-                    const byte S2301 = 0b1011_0001;  // A B C D -> B A D C
-                    const byte S1032 = 0b0100_1110;  // A B C D -> C D A B
-
-                    v_s1 = Sse2.Add(v_s1, Sse2.Shuffle(v_s1, S2301));
-                    v_s1 = Sse2.Add(v_s1, Sse2.Shuffle(v_s1, S1032));
-
-                    s1 += (uint)v_s1.ToScalar();
-
-                    v_s2 = Sse2.Add(v_s2, Sse2.Shuffle(v_s2, S2301));
-                    v_s2 = Sse2.Add(v_s2, Sse2.Shuffle(v_s2, S1032));
-
-                    s2 = (uint)v_s2.ToScalar();
-
-                    // Reduce.
-                    s1 %= BASE;
-                    s2 %= BASE;
-                }
-            }
-
-            ref byte bufferRef = ref MemoryMarshal.GetReference(buffer);
-
-            if (length > 0)
-            {
-                if (length >= 16)
-                {
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    length -= 16;
-                }
-
-                while (length-- > 0)
-                {
-                    s2 += s1 += Unsafe.Add(ref bufferRef, index++);
-                }
-
-                if (s1 >= BASE)
-                {
-                    s1 -= BASE;
-                }
-
-                s2 %= BASE;
-            }
-
-            return s1 | (s2 << 16);
-        }
-#endif
-
-        private static uint CalculateScalar(uint adler, ReadOnlySpan<byte> buffer)
-        {
-            uint s1 = adler & 0xFFFF;
-            uint s2 = (adler >> 16) & 0xFFFF;
-            uint k;
-
-            ref byte bufferRef = ref MemoryMarshal.GetReference<byte>(buffer);
-            uint length = (uint)buffer.Length;
-            int index = 0;
-
-            while (length > 0)
-            {
-                k = length < NMAX ? length : NMAX;
-                length -= k;
-
-                while (k >= 16)
-                {
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    s1 += Unsafe.Add(ref bufferRef, index++);
-                    s2 += s1;
-                    k -= 16;
-                }
-
-                if (k != 0)
-                {
-                    do
-                    {
-                        s1 += Unsafe.Add(ref bufferRef, index++);
-                        s2 += s1;
-                    }
-                    while (--k != 0);
-                }
-
-                s1 %= BASE;
-                s2 %= BASE;
-            }
-
-            return (s2 << 16) | s1;
-        }
-    }
-}

src/SharpCompress/Common/Rar/RarEntry.cs

@@ -10,7 +10,7 @@ namespace SharpCompress.Common.Rar
         /// <summary>
         /// As the V2017 port isn't complete, add this check to use the legacy Rar code.
         /// </summary>
-        internal bool IsRarV3 => FileHeader.CompressionAlgorithm == 29 || FileHeader.CompressionAlgorithm == 36;
+        internal bool IsRarV3 => FileHeader.CompressionAlgorithm == 20 || FileHeader.CompressionAlgorithm == 26 || FileHeader.CompressionAlgorithm == 29 || FileHeader.CompressionAlgorithm == 36; //Nanook - Added 20+26 as Test arc from WinRar2.8 (algo 20) was failing with 2017 code
 
         /// <summary>
         /// The File's 32 bit CRC Hash

src/SharpCompress/SharpCompress.csproj

@@ -2,9 +2,9 @@
   <PropertyGroup>
     <AssemblyTitle>SharpCompress - Pure C# Decompression/Compression</AssemblyTitle>
     <NeutralLanguage>en-US</NeutralLanguage>
-    <VersionPrefix>0.30.1</VersionPrefix>
-    <AssemblyVersion>0.30.1</AssemblyVersion>
-    <FileVersion>0.30.1</FileVersion>
+    <VersionPrefix>0.31.0</VersionPrefix>
+    <AssemblyVersion>0.31.0</AssemblyVersion>
+    <FileVersion>0.31.0</FileVersion>
     <Authors>Adam Hathcock</Authors>
     <TargetFrameworks>net461;netstandard2.0;netstandard2.1;netcoreapp3.1;net5.0</TargetFrameworks>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>

tests/SharpCompress.Test/Rar/RarArchiveTests.cs

@@ -360,6 +360,31 @@ namespace SharpCompress.Test.Rar
             ArchiveFileRead("Rar5.solid.rar");
         }
 
+        [Fact]
+        public void Rar2_Multi_ArchiveStreamRead()
+        {
+            DoRar_Multi_ArchiveStreamRead(new string[] {
+                "Rar2.multi.rar",
+                "Rar2.multi.r00",
+                "Rar2.multi.r01",
+                "Rar2.multi.r02",
+                "Rar2.multi.r03",
+                "Rar2.multi.r04",
+                "Rar2.multi.r05"}, false);
+        }
+
+        [Fact]
+        public void Rar2_Multi_ArchiveFileRead()
+        {
+            ArchiveFileRead("Rar2.multi.rar"); //r00, r01...
+        }
+
+        [Fact]
+        public void Rar2_ArchiveFileRead()
+        {
+            ArchiveFileRead("Rar2.rar");
+        }
+
         [Fact]
         public void Rar_Multi_ArchiveFileRead()
         {

tests/SharpCompress.Test/Streams/ZlibBaseStreamTests.cs

@@ -61,7 +61,7 @@ namespace SharpCompress.Test.Streams
             }
         }
 
-        public void Compress(Stream input, Stream output, int compressionLevel)
+        private void Compress(Stream input, Stream output, int compressionLevel)
         {
             using (var zlibStream = new ZlibStream(new NonDisposingStream(output), CompressionMode.Compress, (CompressionLevel)compressionLevel))
             {
@@ -70,7 +70,7 @@ namespace SharpCompress.Test.Streams
             }
         }
 
-        public void Decompress(Stream input, Stream output)
+        private void Decompress(Stream input, Stream output)
         {
             using (var zlibStream = new ZlibStream(new NonDisposingStream(input), CompressionMode.Decompress))
             {