message: spelling: calculated
diff: one's complement of the obtained CRC value.
  4. Only for CRC-DNP: After all input processing, the one's complement
  - of the CRC is calcluated and the two bytes of the CRC are swapped.
  + of the CRC is calculated and the two bytes of the CRC are swapped.
  5. Only for CRC-Kermit and CRC-SICK: After all input processing, the
  - one's complement of the CRC is calcluated and the two bytes of the CRC
  + one's complement of the CRC is calculated and the two bytes of the CRC
  are swapped.
  