public void Combine(int crc, int length)
{
uint[] even = new uint[32]; // even-power-of-two zeros operator
uint[] odd = new uint[32]; // odd-power-of-two zeros operator
if (length == 0)
return;
uint crc1 = ~_RunningCrc32Result;
uint crc2 = (uint)crc;
// put operator for one zero bit in odd
odd[0] = 0xEDB88320; // the CRC-32 polynomial
uint row = 1;
for (int i = 1; i < 32; i++)
{
odd[i] = row;
row <<= 1;
}
// put operator for two zero bits in even
gf2_matrix_square(even, odd);
// put operator for four zero bits in odd
gf2_matrix_square(odd, even);
uint len2 = (uint)length;
// apply len2 zeros to crc1 (first square will put the operator for one
// zero byte, eight zero bits, in even)
do
{
// apply zeros operator for this bit of len2
gf2_matrix_square(even, odd);
if ((len2 & 1) == 1)
crc1 = gf2_matrix_times(even, crc1);
len2 >>= 1;
if (len2 == 0)
break;
// another iteration of the loop with odd and even swapped
gf2_matrix_square(odd, even);
if ((len2 & 1) == 1)
crc1 = gf2_matrix_times(odd, crc1);
len2 >>= 1;
} while (len2 != 0);
crc1 ^= crc2;
_RunningCrc32Result = ~crc1;
//return (int) crc1;
return;
}
