public static unsafe UInt32 CalculateForPacketBuffer(ConanStream packetBuffer)
{
fixed(byte *fix = packetBuffer.GetBuffer())
{
var buffer = (UInt32 *)fix + 2; // skip length and hash
var len = packetBuffer.Length - sizeof(UInt32) * 2;
var crc32 = 0xffffffff;
UInt32 offset = 0;
if (len >= 32)
{
for (UInt32 i = 0; i < len >> 5; i++)
{
crc32 ^= buffer[offset];
len -= 4;
for (UInt32 ii = 0; ii < 7; ii++)
{
offset++;
crc32 = CrcTab2[crc32 >> 16 & 0xFF] ^ CrcTab3[crc32 >> 8 & 0xFF] ^ CrcTab1[crc32 >> 24] ^
CrcTab4[crc32 & 0xFF] ^ buffer[offset];
len -= 4;
}
crc32 = CrcTab2[crc32 >> 16 & 0xFF] ^ CrcTab3[crc32 >> 8 & 0xFF] ^ CrcTab1[crc32 >> 24] ^
CrcTab4[crc32 & 0xFF];
offset++;
}
}
if (len >= offset)
{
for (UInt32 i = 0; i < (len >> 2); i++)
{
crc32 ^= buffer[offset];
len -= 4;
crc32 = CrcTab2[crc32 >> 16 & 0xFF] ^ CrcTab3[crc32 >> 8 & 0xFF] ^ CrcTab1[crc32 >> 24] ^
CrcTab4[crc32 & 0xFF];
offset++;
}
}
if (len > 0)
{
offset *= 4;
for (UInt32 i = 0; i < len; i++)
{
var tmp = *(byte *)((UInt64)buffer + offset);
crc32 = (crc32 >> 8) ^ CrcTab1[(tmp ^ crc32) & 0xFF];
offset++;
}
}
return(crc32 ^ 0xFFFFFFFF);
}
}
