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using System;
using System.IO;
using System.Runtime.InteropServices;
namespace Ionic.Crc
{
[Guid("ebc25cf6-9120-4283-b972-0e5520d0000C")]
[ComVisible(true)]
[ClassInterface(ClassInterfaceType.AutoDispatch)]
public class CRC32
{
public long TotalBytesRead
{
get
{
return this._TotalBytesRead;
}
}
public int Crc32Result
{
get
{
return (int)(~(int)this._register);
}
}
private uint dwPolynomial;
private long _TotalBytesRead;
private bool reverseBits;
private uint[] crc32Table;
private const int BUFFER_SIZE = 8192;
private uint _register = uint.MaxValue;
public int GetCrc32(Stream input)
{
return this.GetCrc32AndCopy(input, null);
}
public int GetCrc32AndCopy(Stream input, Stream output)
{
bool flag = input == null;
if (flag)
{
throw new Exception("The input stream must not be null.");
}
byte[] array = new byte[8192];
int count = 8192;
this._TotalBytesRead = 0L;
int i = input.Read(array, 0, count);
bool flag2 = output != null;
if (flag2)
{
output.Write(array, 0, i);
}
this._TotalBytesRead += (long)i;
while (i > 0)
{
this.SlurpBlock(array, 0, i);
i = input.Read(array, 0, count);
bool flag3 = output != null;
if (flag3)
{
output.Write(array, 0, i);
}
this._TotalBytesRead += (long)i;
}
return (int)(~(int)this._register);
}
public int ComputeCrc32(int W, byte B)
{
return this._InternalComputeCrc32((uint)W, B);
}
internal int _InternalComputeCrc32(uint W, byte B)
{
return (int)(this.crc32Table[(int)((W ^ (uint)B) & 255u)] ^ W >> 8);
}
public void SlurpBlock(byte[] block, int offset, int count)
{
bool flag = block == null;
if (flag)
{
throw new Exception("The data buffer must not be null.");
}
for (int i = 0; i < count; i++)
{
int num = offset + i;
byte b = block[num];
bool flag2 = this.reverseBits;
if (flag2)
{
uint num2 = this._register >> 24 ^ (uint)b;
this._register = (this._register << 8 ^ this.crc32Table[(int)num2]);
}
else
{
uint num3 = (this._register & 255u) ^ (uint)b;
this._register = (this._register >> 8 ^ this.crc32Table[(int)num3]);
}
}
this._TotalBytesRead += (long)count;
}
public void UpdateCRC(byte b)
{
bool flag = this.reverseBits;
if (flag)
{
uint num = this._register >> 24 ^ (uint)b;
this._register = (this._register << 8 ^ this.crc32Table[(int)num]);
}
else
{
uint num2 = (this._register & 255u) ^ (uint)b;
this._register = (this._register >> 8 ^ this.crc32Table[(int)num2]);
}
}
public void UpdateCRC(byte b, int n)
{
while (n-- > 0)
{
bool flag = this.reverseBits;
if (flag)
{
uint num = this._register >> 24 ^ (uint)b;
this._register = (this._register << 8 ^ this.crc32Table[(int)((num >= 0u) ? num : (num + 256u))]);
}
else
{
uint num2 = (this._register & 255u) ^ (uint)b;
this._register = (this._register >> 8 ^ this.crc32Table[(int)((num2 >= 0u) ? num2 : (num2 + 256u))]);
}
}
}
private static uint ReverseBits(uint data)
{
uint num = (data & 1431655765u) << 1 | (data >> 1 & 1431655765u);
num = ((num & 858993459u) << 2 | (num >> 2 & 858993459u));
num = ((num & 252645135u) << 4 | (num >> 4 & 252645135u));
return num << 24 | (num & 65280u) << 8 | (num >> 8 & 65280u) | num >> 24;
}
private static byte ReverseBits(byte data)
{
uint num = (uint)data * 131586u;
uint num2 = 17055760u;
uint num3 = num & num2;
uint num4 = num << 2 & num2 << 1;
return (byte)(16781313u * (num3 + num4) >> 24);
}
private void GenerateLookupTable()
{
this.crc32Table = new uint[256];
byte b = 0;
do
{
uint num = (uint)b;
for (byte b2 = 8; b2 > 0; b2 -= 1)
{
bool flag = (num & 1u) == 1u;
if (flag)
{
num = (num >> 1 ^ this.dwPolynomial);
}
else
{
num >>= 1;
}
}
bool flag2 = this.reverseBits;
if (flag2)
{
this.crc32Table[(int)CRC32.ReverseBits(b)] = CRC32.ReverseBits(num);
}
else
{
this.crc32Table[(int)b] = num;
}
b += 1;
}
while (b > 0);
}
private uint gf2_matrix_times(uint[] matrix, uint vec)
{
uint num = 0u;
int num2 = 0;
while (vec > 0u)
{
bool flag = (vec & 1u) == 1u;
if (flag)
{
num ^= matrix[num2];
}
vec >>= 1;
num2++;
}
return num;
}
private void gf2_matrix_square(uint[] square, uint[] mat)
{
for (int i = 0; i < 32; i++)
{
square[i] = this.gf2_matrix_times(mat, mat[i]);
}
}
public void Combine(int crc, int length)
{
uint[] array = new uint[32];
uint[] array2 = new uint[32];
bool flag = length == 0;
if (!flag)
{
uint num = ~this._register;
array2[0] = this.dwPolynomial;
uint num2 = 1u;
for (int i = 1; i < 32; i++)
{
array2[i] = num2;
num2 <<= 1;
}
this.gf2_matrix_square(array, array2);
this.gf2_matrix_square(array2, array);
uint num3 = (uint)length;
do
{
this.gf2_matrix_square(array, array2);
bool flag2 = (num3 & 1u) == 1u;
if (flag2)
{
num = this.gf2_matrix_times(array, num);
}
num3 >>= 1;
bool flag3 = num3 == 0u;
if (flag3)
{
break;
}
this.gf2_matrix_square(array2, array);
bool flag4 = (num3 & 1u) == 1u;
if (flag4)
{
num = this.gf2_matrix_times(array2, num);
}
num3 >>= 1;
}
while (num3 > 0u);
num ^= (uint)crc;
this._register = ~num;
}
}
public CRC32() : this(false)
{
}
public CRC32(bool reverseBits) : this(-306674912, reverseBits)
{
}
public CRC32(int polynomial, bool reverseBits)
{
this.reverseBits = reverseBits;
this.dwPolynomial = (uint)polynomial;
this.GenerateLookupTable();
}
public void Reset()
{
this._register = uint.MaxValue;
}
}
}
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