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Clean up SHA1

This commit is contained in:
YoshiRulz 2022-11-24 20:06:05 +10:00
parent 4566b744d9
commit 9a0403617b
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GPG Key ID: C4DE31C245353FB7
1 changed files with 28 additions and 40 deletions
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68
src/BizHawk.Common/checksums/SHA1Checksum.cs
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@ -7,40 +7,6 @@ using BizHawk.Common.BufferExtensions;
namespace BizHawk.Common
{
public interface ISHA1
{
byte[] ComputeHash(byte[] buffer);
}
public sealed class NETSHA1 : ISHA1
{
private readonly SHA1 _sha1Impl;
public NETSHA1()
{
_sha1Impl = SHA1.Create();
Debug.Assert(_sha1Impl.CanReuseTransform && _sha1Impl.HashSize is SHA1Checksum.EXPECTED_LENGTH);
}
public byte[] ComputeHash(byte[] buffer)
=> _sha1Impl.ComputeHash(buffer);
}
public sealed class FastSHA1 : ISHA1
{
public unsafe byte[] ComputeHash(byte[] buffer)
{
// Set SHA1 start state
var state = stackalloc uint[] { 0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0 };
// This will use dedicated SHA instructions, which perform 4x faster than a generic implementation
LibBizHash.BizCalcSha1((IntPtr)state, buffer, buffer.Length);
// The copy seems wasteful, but pinning the state down actually has a bigger performance impact
var ret = new byte[20];
Marshal.Copy((IntPtr)state, ret, 0, 20);
return ret;
}
}
/// <summary>uses <see cref="SHA1"/> implementation from BCL</summary>
/// <seealso cref="CRC32Checksum"/>
/// <seealso cref="MD5Checksum"/>
@ -70,27 +36,49 @@ namespace BizHawk.Common
return impl.GetHashAndReset();
}
#else
private static ISHA1? _sha1Impl;
private static unsafe byte[] UnmanagedImpl(byte[] buffer)
{
// Set SHA1 start state
var state = stackalloc uint[] { 0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0 };
// This will use dedicated SHA instructions, which perform 4x faster than a generic implementation
LibBizHash.BizCalcSha1((IntPtr) state, buffer, buffer.Length);
// The copy seems wasteful, but pinning the state down actually has a bigger performance impact
var ret = new byte[20];
Marshal.Copy((IntPtr) state, ret, 0, 20);
return ret;
}
private static ISHA1 SHA1Impl
private static SHA1? _sha1Impl;
private static SHA1 SHA1Impl
{
get
{
if (_sha1Impl == null)
{
_sha1Impl = LibBizHash.BizSupportsShaInstructions()
? new FastSHA1()
: new NETSHA1();
_sha1Impl = SHA1.Create();
Debug.Assert(_sha1Impl.CanReuseTransform && _sha1Impl.HashSize is EXPECTED_LENGTH);
}
return _sha1Impl;
}
}
public static byte[] Compute(byte[] data)
=> SHA1Impl.ComputeHash(data);
=> LibBizHash.BizSupportsShaInstructions()
? UnmanagedImpl(data)
: SHA1Impl.ComputeHash(data);
public static byte[] ComputeConcat(byte[] dataA, byte[] dataB)
{
if (LibBizHash.BizSupportsShaInstructions())
{
var concat = new byte[dataA.Length + dataB.Length];
Array.Copy(sourceArray: dataA, destinationArray: concat, length: dataA.Length);
Array.Copy(
sourceArray: dataB, sourceIndex: 0,
destinationArray: concat, destinationIndex: dataA.Length, length: dataB.Length);
return UnmanagedImpl(concat);
}
using var impl = IncrementalHash.CreateHash(HashAlgorithmName.SHA1);
impl.AppendData(dataA);
impl.AppendData(dataB);