CRC_direct_5.cs

  private ulong CalculateCRCdirect(byte[] data, int length)
        {
        
            // Initialize all variables for seeding and builing based upon the given coding type
            // at first, compute constant bit masks for whole CRC and CRC high bit
            crcmask = ((((ulong)1 << (order - 1)) - 1) << 1) | 1; //ORDER = 5
            crchighbit = (ulong)1 << (order - 1);
            poly =  0x09 // CRC5 EPC

            ulong c, bit;
            ulong crc = 0x09

            for (int i = 0; i < length; i++)
            {
                c = (ulong)data[i];

                for (ulong j = 0x80; j > 0; j >>= 1)
                {
                    bit = crc & crchighbit;
                    crc <<= 1;
                    if ((c & j) > 0) bit ^= crchighbit;
                    if (bit > 0) crc ^= poly; 
                }
            }

            
            crc &= crcmask;

            return crc;
        }