buffer-crc32

What is buffer-crc32?

The buffer-crc32 package is a Node.js module for calculating CRC32 checksums of buffers. It's a fast and simple utility for generating checksums of data, which can be useful for verifying the integrity of data being transferred over a network or stored.

What are buffer-crc32's main functionalities?

Calculate CRC32 checksum

This feature allows you to calculate the CRC32 checksum of a given buffer. The code sample demonstrates how to calculate the checksum of a 'Hello World' string.

const crc32 = require('buffer-crc32');
const buffer = Buffer.from('Hello World');
const checksum = crc32(buffer);
console.log(checksum.toString('hex'));

Update existing checksum with new data

This feature enables you to update an existing checksum with new data. The code sample shows how to calculate the checksum for 'Hello', then update it with ' World' to get the checksum for 'Hello World'.

const crc32 = require('buffer-crc32');
let checksum = crc32(Buffer.from('Hello'));
checksum = crc32(Buffer.from(' World'), checksum);
console.log(checksum.toString('hex'));

Other packages similar to buffer-crc32

crc

The 'crc' package offers a wider range of CRC algorithms, including CRC32. It provides more flexibility compared to buffer-crc32 but might be slightly more complex to use for simple CRC32 calculations.

crc32-stream

This package is designed for streaming data and calculating CRC32 checksums on the fly. It's more suited for scenarios where data is being processed in streams, compared to buffer-crc32 which works on buffers.

README

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