public static byte[] CalculateCRC(IEnumerable <byte> bytes, uint crcInitialValue = 0x0, CRCType crcPolynomial = CRCType.CRC16CCITTPolynomial)
{
uint crc = crcInitialValue;
CRCEngine crcEngine = new CRCEngine(crcPolynomial);
var crcLength = crcPolynomial.GetLength();
// Byte little endian order
switch (crcLength)
{
case 2:
crc = crcEngine.CalculateCrc16(bytes, (ushort)crc);
return(new[] { (byte)crc, (byte)(crc >> 8) });
case 4:
crc = crcEngine.CalculateCrc32(bytes, crc);
return(new[] { (byte)crc, (byte)(crc >> 8), (byte)(crc >> 16), (byte)(crc >> 24) });
default:
Logger.Log(LogLevel.Error, "Cannot calculate CRC of invalid length {0}", crcLength);
return(new byte[crcLength]);
}
}
public CRCEngine(CRCType polynomial)
{
this.reversedPolynomial = polynomial.GetLength() == 4
? BitHelper.ReverseBits((uint)polynomial)
: BitHelper.ReverseBits((ushort)polynomial); // this cast is needed to rotate only lower bits
}
