@lichtblick/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:

``ts
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

`ts
import { crc32 } from "@lichtblick/crc";

const data = new Uint8Array(...);

const crc = crc32(data);
`

`ts
import { crc32Init, crc32Update, crc32Final } from "@lichtblick/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

@lichtblick/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