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Add native Fletcher-32.

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Natalia Portillo
2021-10-14 00:17:01 +01:00
parent 64a2c9f9fb
commit a1259eaf16
3 changed files with 96 additions and 47 deletions
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95
Aaru6.Checksums/FletcherContext.cs
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@@ -44,22 +44,30 @@ namespace Aaru6.Checksums
/// <summary>Implements the Fletcher-32 algorithm</summary>
public sealed class Fletcher32Context : IChecksum
{
const ushort FLETCHER_MODULE = 0xFFFF;
const uint NMAX = 5552;
ushort _sum1, _sum2;
const ushort FLETCHER_MODULE = 0xFFFF;
const uint NMAX = 5552;
readonly IntPtr _nativeContext;
ushort _sum1, _sum2;
readonly bool _useNative;
/// <summary>Initializes the Fletcher-32 sums</summary>
public Fletcher32Context()
{
_sum1 = 0xFFFF;
_sum2 = 0xFFFF;
if(!Native.IsSupported)
return;
_nativeContext = fletcher32_init();
_useNative = _nativeContext != IntPtr.Zero;
}
/// <inheritdoc />
/// <summary>Updates the hash with data.</summary>
/// <param name="data">Data buffer.</param>
/// <param name="len">Length of buffer to hash.</param>
public void Update(byte[] data, uint len) => Step(ref _sum1, ref _sum2, data, len);
public void Update(byte[] data, uint len) => Step(ref _sum1, ref _sum2, data, len, _useNative, _nativeContext);
/// <inheritdoc />
/// <summary>Updates the hash with data.</summary>
@@ -72,6 +80,12 @@ namespace Aaru6.Checksums
{
uint finalSum = (uint)((_sum2 << 16) | _sum1);
if(!_useNative)
return BigEndianBitConverter.GetBytes(finalSum);
fletcher32_final(_nativeContext, ref finalSum);
fletcher32_free(_nativeContext);
return BigEndianBitConverter.GetBytes(finalSum);
}
@@ -79,8 +93,15 @@ namespace Aaru6.Checksums
/// <summary>Returns a hexadecimal representation of the hash value.</summary>
public string End()
{
uint finalSum = (uint)((_sum2 << 16) | _sum1);
var fletcherOutput = new StringBuilder();
uint finalSum = (uint)((_sum2 << 16) | _sum1);
if(_useNative)
{
fletcher32_final(_nativeContext, ref finalSum);
fletcher32_free(_nativeContext);
}
var fletcherOutput = new StringBuilder();
for(int i = 0; i < BigEndianBitConverter.GetBytes(finalSum).Length; i++)
fletcherOutput.Append(BigEndianBitConverter.GetBytes(finalSum)[i].ToString("x2"));
@@ -88,8 +109,28 @@ namespace Aaru6.Checksums
return fletcherOutput.ToString();
}
static void Step(ref ushort previousSum1, ref ushort previousSum2, byte[] data, uint len)
[DllImport("libAaru.Checksums.Native", SetLastError = true)]
static extern IntPtr fletcher32_init();
[DllImport("libAaru.Checksums.Native", SetLastError = true)]
static extern int fletcher32_update(IntPtr ctx, byte[] data, uint len);
[DllImport("libAaru.Checksums.Native", SetLastError = true)]
static extern int fletcher32_final(IntPtr ctx, ref uint crc);
[DllImport("libAaru.Checksums.Native", SetLastError = true)]
static extern void fletcher32_free(IntPtr ctx);
static void Step(ref ushort previousSum1, ref ushort previousSum2, byte[] data, uint len, bool useNative,
IntPtr nativeContext)
{
if(useNative)
{
fletcher32_update(nativeContext, data, len);
return;
}
uint sum1 = previousSum1;
uint sum2 = previousSum2;
uint n;
@@ -253,6 +294,17 @@ namespace Aaru6.Checksums
/// <param name="hash">Byte array of the hash value.</param>
public static string File(string filename, out byte[] hash)
{
bool useNative = Native.IsSupported;
IntPtr nativeContext = IntPtr.Zero;
if(useNative)
{
nativeContext = fletcher32_init();
if(nativeContext == IntPtr.Zero)
useNative = false;
}
var fileStream = new FileStream(filename, FileMode.Open);
ushort localSum1 = 0xFFFF;
@@ -263,13 +315,19 @@ namespace Aaru6.Checksums
while(read > 0)
{
Step(ref localSum1, ref localSum2, buffer, (uint)read);
Step(ref localSum1, ref localSum2, buffer, (uint)read, useNative, nativeContext);
read = fileStream.Read(buffer, 0, 65536);
}
uint finalSum = (uint)((localSum2 << 16) | localSum1);
if(useNative)
{
fletcher32_final(nativeContext, ref finalSum);
fletcher32_free(nativeContext);
}
hash = BigEndianBitConverter.GetBytes(finalSum);
var fletcherOutput = new StringBuilder();
@@ -288,13 +346,30 @@ namespace Aaru6.Checksums
/// <param name="hash">Byte array of the hash value.</param>
public static string Data(byte[] data, uint len, out byte[] hash)
{
bool useNative = Native.IsSupported;
IntPtr nativeContext = IntPtr.Zero;
if(useNative)
{
nativeContext = fletcher32_init();
if(nativeContext == IntPtr.Zero)
useNative = false;
}
ushort localSum1 = 0xFFFF;
ushort localSum2 = 0xFFFF;
Step(ref localSum1, ref localSum2, data, len);
Step(ref localSum1, ref localSum2, data, len, useNative, nativeContext);
uint finalSum = (uint)((localSum2 << 16) | localSum1);
if(useNative)
{
fletcher32_final(nativeContext, ref finalSum);
fletcher32_free(nativeContext);
}
hash = BigEndianBitConverter.GetBytes(finalSum);
var adlerOutput = new StringBuilder();
@@ -319,8 +394,8 @@ namespace Aaru6.Checksums
const byte NMAX = 22;
readonly IntPtr _nativeContext;
byte _sum1, _sum2;
readonly bool _useNative;
byte _sum1, _sum2;
/// <summary>Initializes the Fletcher-16 sums</summary>
public Fletcher16Context()