/// <summary>
/// calculate EDC crc tables
/// </summary>
static void Prep_EDC()
{
//14.3 of yellowbook specifies EDC crc as P(x) = (x^16 + x^15 + x^2 + 1) . (x^16 + x^2 + x + 1)
//confirmation at http://cdmagediscussion.yuku.com/topic/742/EDC-calculation
//int Pa = 0x18005;
//int Pb = 0x10007;
//long Px = 0;
//for (int i = 0; i <= 16; i++)
// for (int j = 0; j <= 16; j++)
// {
// //multiply Pa[i] * Pb[j]
// int bit = (Pa >> i) & (Pb >> j) & 1;
// //xor into result, achieving modulo-2 thereby
// Px ^= (long)bit << (i + j);
// }
//uint edc_poly = (uint)Px;
const uint edc_poly = 0x8001801B;
//generate the CRC table
uint reverse_edc_poly = BitReverse.Reverse32(edc_poly);
for (uint i = 0; i < 256; ++i)
{
uint crc = i;
for (int j = 8; j > 0; --j)
{
if ((crc & 1) == 1)
{
crc = ((crc >> 1) ^ reverse_edc_poly);
}
else
{
crc >>= 1;
}
}
edc_table[i] = crc;
}
}
public static void Setup()
{
BitReverse.Setup();
TwiddleFactors.Setup();
}
static Transform()
{
BitReverse.Setup();
TwiddleFactors.Setup();
}
