mermshaus/CRC

I’m not an expert on the topic by any means. Therefore, I have trouble finding and verifying information about common CRC algorithms.

Implemented algorithms

Alias names in parentheses.

• CRC-1 [1]
• CRC-16 [2]
• CRC-16/IBM-3740 (CRC-16/CCITT-FALSE)
• CRC-16/DNP
• CRC-16/MODBUS
• CRC-16/IBM-SDLC (CRC16-QT [3])
• CRC-16/USB
• CRC-16/XMODEM (CRC-16/ZMODEM)

1: Might be a misnomer inherited from the algorithm list this library was built against.

2: Most likely CRC-16/ARC.

3: This was also part of the original library. It doesn’t seem to be a catalogue alias. That’s why it’s not formatted as one.

Usage example

<?php

// Autoloading via Composer
require __DIR__ . '/vendor/autoload.php';

$crc = new \mermshaus\CRC\CRC16IBM3740();

$crc->update('Hello');
$crc->update(' World!');

$checksum = $crc->finish();

var_dump(bin2hex($checksum)); // string(4) "882a"

Testing

Note: The current test setup tries to use the PHP version installed on the system (php command). If none is found, it will try to build a Docker container based on php-cli and use that.

$ make test

Credits

• This library is mostly a port of Digest CRC for Ruby by Hal Brodigan.

Links

• Digest CRC. The Ruby library on which this library is based.
• pycrc. A tool for generating C code and corresponding lookup tables for diverse CRC algorithms. Used by Digest CRC.
• CRC calculation. An online calculator to generate checksums for arbitrary polynomials and input. Recommended by pycrc.
• On-line CRC calculation and free library. Another online calculator for some CRC algorithms.
• Catalogue of parametrised CRC algorithms. Information about many different CRC algorithms.