Checksum

Checksum function libraries.

This module provides a number of checksum functions. Most notably is the CRC16-CCITT and the CRC16 (lightweight) modules which provide support for the CRC16 checksum.

CRC16-CCITT only provides an implementation of the CCITT flavor of CRC16 (polynomial $ x^{16} + x^{12} + x^{5} + 1 $) for big-endian numbers with starting seed 0x1d0f (though others can be provided), while CRC16 (lightweight) is more generalized, since it takes the hexadecimal representation of the polynomial as a parameter and provides functions and standardized polynomials for both big- and little-endian numbers.

The caveat of CRC16 (lightweight) is that it is significantly slower (approximately factor 8) than CRC16-CCITT since the latter is able to calculate the checksum byte-wise, while the first calculates needs to calculate it bit-wise. CRC16-CCITT achieves this advantage by using a look-up table that provides the checksum for every possible byte-value. It thus trades of memory against speed. If your platform is rather small equipped in memory you should prefer the CRC16 (lightweight) version.