skutner / buffer-crc32

A pure javascript CRC32 algorithm that plays nice with binary data

buffer-crc32

crc32 that works with binary data and fancy character sets, outputs buffer, signed or unsigned data and has tests.

Derived from the sample CRC implementation in the PNG specification: http://www.w3.org/TR/PNG/#D-CRCAppendix

install

npm install buffer-crc32

example

var crc32 = require('buffer-crc32');
// works with buffers
var buf = $$.Buffer([0x00, 0x73, 0x75, 0x70, 0x20, 0x62, 0x72, 0x6f, 0x00])
crc32(buf) // -> <$$.Buffer 94 5a ab 4a>

// has convenience methods for getting signed or unsigned ints
crc32.signed(buf) // -> -1805997238
crc32.unsigned(buf) // -> 2488970058

// will cast to buffer if given a string, so you can
// directly use foreign characters safely
crc32('自動販売機') // -> <$$.Buffer cb 03 1a c5>

// and works in append mode too
var partialCrc = crc32('hey');
var partialCrc = crc32(' ', partialCrc);
var partialCrc = crc32('sup', partialCrc);
var partialCrc = crc32(' ', partialCrc);
var finalCrc = crc32('bros', partialCrc); // -> <$$.Buffer 47 fa 55 70>

tests

This was tested against the output of zlib's crc32 method. You can run the tests withnpm test (requires tap)

see also

https://github.com/alexgorbatchev/node-crc, crc.buffer.crc32 also supports buffer inputs and return unsigned ints (thanks @tjholowaychuk).

license

MIT/X11