README.md

@foxglove/crc

Fast CRC32 computation in TypeScript

Introduction

A Cyclic Redundancy Check (CRC) is a calculation used to detect errors in data transmission.

This library implements CRC32, the standard 32-bit CRC using the binary polynomial 0xEDB88320. This is the same algorithm used in PNG, zlib, and other popular applications.

Interface

The following functions are exported from this package:

function crc32Init(): number;
function crc32Update(prev: number, data: ArrayBufferView): number;
function crc32Final(prev: number): number;

function crc32(data: ArrayBufferView): number;

Note: Since the CRC algorithm works with unsigned data, the crc32 and crc32Final functions always return non-negative numbers. For example, CRC32(0x01) returns 2768625435 rather than -1526341861.

Usage

import { crc32 } from "@foxglove/crc";

const data = new Uint8Array(...);

const crc = crc32(data);

import { crc32Init, crc32Update, crc32Final } from "@foxglove/crc";

let crc = crc32Init();
while (/* more data available */) {
  crc = crc32Update(crc, data);
}
crc = crc32Final(crc);

Benchmarks

This package achieves a >5x performance improvement over many other CRC packages, because of the multi-byte algorithms used (adapted from https://github.com/komrad36/CRC).

The following benchmarks were recorded on a MacBook Pro with an M1 Pro chip and 16GB of RAM. Each iteration ("op") is processing 1MB of data.

$ yarn bench
...
  crc:
    355 ops/s, ±0.56%     | 81.52% slower

  node-crc:
    376 ops/s, ±0.14%     | 80.43% slower

  crc-32:
    1 057 ops/s, ±0.16%   | 44.98% slower

  polycrc:
    327 ops/s, ±0.21%     | slowest, 82.98% slower

  this package:
    1 921 ops/s, ±0.18%   | fastest

References

For further information about CRCs and their computation, see:

• https://en.wikipedia.org/wiki/Computation_of_cyclic_redundancy_checks
• https://github.com/komrad36/CRC
• https://create.stephan-brumme.com/crc32/
• https://zlib.net/crc_v3.txt
• https://github.com/Michaelangel007/crc32
• https://docs.microsoft.com/en-us/openspecs/office_protocols/ms-abs/06966aa2-70da-4bf9-8448-3355f277cd77

License

@foxglove/crc is licensed under the MIT License.

Releasing

1. Run yarn version --[major|minor|patch] to bump version
2. Run git push && git push --tags to push new tag
3. GitHub Actions will take care of the rest

Stay in touch

Join our Slack channel to ask questions, share feedback, and stay up to date on what our team is working on.