crcengine 0.1.0

A library for CRC calculation

CrcEngine

A python library for CRC calculation providing table-based as well as bit-bashing implementations (for reference).

• Free software: GNU General Public License v3

• Documentation: https://crcengine.readthedocs.io.

Usage

Use pre-defined algorithms such as CRC32 are available. Tailored algorithms can be created by calling CrcEngine.create() and other related methods.

A calculation engine for a specific named algorithm can be obtained using CrcEngine.new(). Algorithms which are not pre-defined can be created using CrcEngine.create()

A list of pre-defined algorithms can be obtained using CrcEngine.algorithms_available()

Examples

Using a pre-defined algorithm

import crcengine
crc_algorithm = crcengine.new('crc32-bzip2')
result = crc_algorithm(b'123456789')
print('CRC=0x{:08x}'.format(result))

Output: > CRC=0xfc891918

Defining an algorithm .. code-block:

import crcengine
crc_openpgp = crcengine.create(0x864cfb, 24, 0xb704ce, ref_in=False,
                               ref_out=False, xor_out=0, name='crc-24-openpgp')

Code Generation

The library can generate C code for a given table-algorithm. The code produced is intended to be a reasonable compromise between size, complexity and speed without requiring allocation of memory for table generation at runtime.

Faster implementations of specific algorithms can be achived in software which unroll loops and pipeline the operations different bytes to introduce parallelism in the calculation see intel_soft_src for example. Some processors also include instructions specifically for crc calculation.

Downloading

• The source is available on github

• Git clone crcengine.git

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With thanks to Greg Cook for providing such a thoroughly collated list of CRC definitions