Checksum

Checksum function libraries. More...

Detailed Description

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.

It is worth noting that the checksumming algorithms provided should not be used for security purposes (e.g. integrity or authentication), since they are not cryptographically secure.

Topics
	CRC-8
	CRC-8 checksum algorithms.
	CRC16 (lightweight)
	Lightweight CRC16 checksum algorithms.
	CRC16-CCITT
	Variations of CRC16-CCITT checksum algorithms.
	CRC32
	CRC32 checksum algorithm implementation according to IEEE standards.
	Fletcher16
	Fletcher16 checksum algorithm.
	Fletcher32
	Fletcher32 checksum algorithm.