CRC

public class CRC
{
static public int[] Table = new int[256];

static
{
for (int i = 0; i < 256; i++)
{
int r = i;
for (int j = 0; j < 8; j++)
if ((r & 1) != 0)
r = (r >>> 1) ^ 0xEDB88320;
else
r >>>= 1;
Table[i] = r;
}
}

int _value = -1;

public void Init()
{
_value = -1;
}

public void Update(byte[] data, int offset, int size)
{
for (int i = 0; i < size; i++)
_value = Table[(_value ^ data[offset + i]) & 0xFF] ^ (_value >>> 8);
}

public void Update(byte[] data)
{
int size = data.length;
for (int i = 0; i < size; i++)
_value = Table[(_value ^ data[i]) & 0xFF] ^ (_value >>> 8);
}

public void UpdateByte(int b)
{
_value = Table[(_value ^ b) & 0xFF] ^ (_value >>> 8);
}

public int GetDigest()
{
return _value ^ (-1);
}
}