anycrc 0.3.3

Python CRC Computation Library

This is a Cython module with bindings to the crcany library. It supports calculating CRC hashes of arbitary sizes as well as updating a crc hash over time.

Installation

pip install anycrc

Usage

Use an existing model:

>>> import anycrc
>>> crc32 = anycrc.Model('CRC32-ISO-HDLC')
>>> crc32.calc(b'Hello World!')
472456355

Read the data in chunks:

>>> crc32.reset()
>>> crc32.calc(b'Hello ')
3928882368
>>> crc32.calc(b'World!')
472456355

Specify the starting CRC value:

>>> crc32.set(3928882368)
>>> crc32.calc('World!')
472456355

Specify your own CRC parameters:

>>> # width, poly, init, refin, refout, xorout
>>> my_crc = anycrc.CRC(10, 0b0101010101, 0x3ff, True, False, 0)
>>> my_crc.calc('Hello World!')
35

The CRC's width cannot exceed your system's maximum integer width.

For a list of pre-built models, check models.py. To get a list of the models at any time, use the following command:

python -m anycrc models

Benchmarks

Calculating the CRC32 for lorem ipsum 10 million times:

Module	Time Elapsed (s)	Speed (MiB/s)	Relative
anycrc	6.660	637.26	1.000
zlib	7.567	560.86	1.136
fastcrc	17.508	242.39	2.629
crcmod-plus	19.619	216.32	2.946

Calculating the CRC32 for the text of lorem ipsum repeated 1 million times in a single pass:

Module	Time Elapsed (s)	Speed (MiB/s)	Relative
anycrc	0.293	1447.36	1.000
zlib	0.496	856.06	1.691
fastcrc	1.310	323.88	4.469
crcmod-plus	1.280	331.44	4.367