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crcany can compute any CRC, given the parameters that describe it. Those parameters are given in the form used on Greg Cook's catalog of CRCs at , where that set of parameters were first defined by Ross Williams in his excellent tutorial on CRCs at .

crcany computes each CRC three different ways. First, computing a bit at a time, as you would in any self-respecting hardware implementation. Second, using the bit-at-a-time algorithm to create a table of 256 CRCs that can be used to compute that CRC a byte at a time. Third, using the byte-wise table to generate another n-1 tables, where n is the number of bytes in the largest integer, to enable computing a CRC a word at a time. The word-wise approach has two flavors, one for little-endian machines, and one for big-endian machines.

The bit-wise calculation can be done on CRCs up to twice the word length, e.g. 128 bits on machines with 64-bit integers. The byte and word-wise calculations can be done on CRCs up to the word size, e.g. up to 64-bit CRCs using 64-bit integers.

crcgen generates C code for each CRC definition read from stdin, putting the resulting code into .h and .c files for each definition in the src/ subdirectory. Test code is also generated in src/crc_test.c. Code is generated for the machine being run on (i.e. with respect to the lengths of the integer types and their endianess), and will generate code for any CRC whose width is less than or equal to the maximum integer size.


Provide once and for all a definitive reference for how to compute any CRC with any of bit, byte, or word-at-a-time algorithms, on any big or little-endian architecture.


This will compile the crcany, crcgen, and mincrc executables:



Test crcany and crcgen using the list of all catalogued CRCs, available here in the file allcrcs.txt, and test mincrc against the abbreviated list using the Makefile:

make test


This code is under the zlib license, permitting free commercial use.


Compute any CRC, a bit at a time, a byte at a time, and a word at a time.



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