aaru-dps/Aaru.Checksums
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General cleanup and refactor.

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This commit is contained in:
Natalia Portillo
2022-03-07 07:36:42 +00:00
parent db8c5c6a53
commit 19c7f3d4ff
22 changed files with 1076 additions and 1544 deletions
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41
CRC16Context.cs
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@@ -30,6 +30,8 @@
// Copyright © 2011-2022 Natalia Portillo
// ****************************************************************************/
namespace Aaru.Checksums;
using System;
using System.IO;
using System.Runtime.InteropServices;
@@ -37,8 +39,6 @@ using System.Text;
using Aaru.CommonTypes.Interfaces;
using Aaru.Helpers;
namespace Aaru.Checksums;
/// <inheritdoc />
/// <summary>Implements a CRC16 algorithm</summary>
public class Crc16Context : IChecksum
@@ -61,11 +61,10 @@ public class Crc16Context : IChecksum
_useNative = Native.IsSupported;
_useCcitt = polynomial == CRC16CCITTContext.CRC16_CCITT_POLY &&
seed == CRC16CCITTContext.CRC16_CCITT_SEED && inverse;
_useCcitt = polynomial == CRC16CCITTContext.CRC16_CCITT_POLY && seed == CRC16CCITTContext.CRC16_CCITT_SEED &&
inverse;
_useIbm = polynomial == CRC16IBMContext.CRC16_IBM_POLY && seed == CRC16IBMContext.CRC16_IBM_SEED &&
!inverse;
_useIbm = polynomial == CRC16IBMContext.CRC16_IBM_POLY && seed == CRC16IBMContext.CRC16_IBM_SEED && !inverse;
if(_useCcitt && _useNative)
{
@@ -181,7 +180,7 @@ public class Crc16Context : IChecksum
byte[] finalBytes = BigEndianBitConverter.GetBytes(final);
for(int i = 0; i < finalBytes.Length; i++)
for(var i = 0; i < finalBytes.Length; i++)
crc16Output.Append(finalBytes[i].ToString("x2"));
return crc16Output.ToString();
@@ -218,7 +217,7 @@ public class Crc16Context : IChecksum
// http://sourceforge.net/projects/slicing-by-8/
ushort crc;
int current_pos = 0;
var current_pos = 0;
const int unroll = 4;
const int bytes_at_once = 8 * unroll;
@@ -233,7 +232,7 @@ public class Crc16Context : IChecksum
// TODO: What trick is Microsoft doing here that's faster than arithmetic conversion
uint one = BitConverter.ToUInt32(data, current_pos) ^ crc;
current_pos += 4;
uint two = BitConverter.ToUInt32(data, current_pos);
var two = BitConverter.ToUInt32(data, current_pos);
current_pos += 4;
crc = (ushort)(table[0][(two >> 24) & 0xFF] ^ table[1][(two >> 16) & 0xFF] ^
@@ -257,7 +256,7 @@ public class Crc16Context : IChecksum
// http://sourceforge.net/projects/slicing-by-8/
ushort crc;
int current_pos = 0;
var current_pos = 0;
const int unroll = 4;
const int bytes_at_once = 8 * unroll;
@@ -289,9 +288,9 @@ public class Crc16Context : IChecksum
static ushort[][] GenerateTable(ushort polynomial, bool inverseTable)
{
ushort[][] table = new ushort[8][];
var table = new ushort[8][];
for(int i = 0; i < 8; i++)
for(var i = 0; i < 8; i++)
table[i] = new ushort[256];
if(!inverseTable)
@@ -299,7 +298,7 @@ public class Crc16Context : IChecksum
{
uint entry = i;
for(int j = 0; j < 8; j++)
for(var j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (entry >> 1) ^ polynomial;
else
@@ -308,7 +307,6 @@ public class Crc16Context : IChecksum
table[0][i] = (ushort)entry;
}
else
{
for(uint i = 0; i < 256; i++)
{
uint entry = i << 8;
@@ -323,16 +321,13 @@ public class Crc16Context : IChecksum
table[0][i] = (ushort)entry;
}
}
}
for(int slice = 1; slice < 8; slice++)
for(int i = 0; i < 256; i++)
{
for(var slice = 1; slice < 8; slice++)
for(var i = 0; i < 256; i++)
if(inverseTable)
table[slice][i] = (ushort)((table[slice - 1][i] << 8) ^ table[0][table[slice - 1][i] >> 8]);
else
table[slice][i] = (ushort)((table[slice - 1][i] >> 8) ^ table[0][table[slice - 1][i] & 0xFF]);
}
return table;
}
@@ -377,8 +372,8 @@ public class Crc16Context : IChecksum
ushort[][] localTable = table ?? GenerateTable(polynomial, inverse);
byte[] buffer = new byte[65536];
int read = fileStream.Read(buffer, 0, 65536);
var buffer = new byte[65536];
int read = fileStream.Read(buffer, 0, 65536);
while(read > 0)
{
@@ -449,8 +444,8 @@ public class Crc16Context : IChecksum
/// <param name="seed">CRC seed</param>
/// <param name="table">CRC lookup table</param>
/// <param name="inverse">Is CRC inverted?</param>
public static string Data(byte[] data, uint len, out byte[] hash, ushort polynomial, ushort seed,
ushort[][] table, bool inverse)
public static string Data(byte[] data, uint len, out byte[] hash, ushort polynomial, ushort seed, ushort[][] table,
bool inverse)
{
bool useNative = Native.IsSupported;