https://github.com/jhermsmeier/node-cyclic-32
A tiny, streaming, seedable CRC32 library, compatible with Node's crypto.Hash API. In less than 100 LOC.
https://github.com/jhermsmeier/node-cyclic-32
checksum crc crc32 streams
Last synced: 3 months ago
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A tiny, streaming, seedable CRC32 library, compatible with Node's crypto.Hash API. In less than 100 LOC.
- Host: GitHub
- URL: https://github.com/jhermsmeier/node-cyclic-32
- Owner: jhermsmeier
- License: mit
- Created: 2017-04-13T14:43:29.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2021-09-19T11:03:20.000Z (about 4 years ago)
- Last Synced: 2025-01-15T13:07:58.971Z (9 months ago)
- Topics: checksum, crc, crc32, streams
- Language: JavaScript
- Homepage:
- Size: 1.01 MB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
Awesome Lists containing this project
README
# cyclic-32
[](https://npmjs.com/package/cyclic-32)
[](https://npmjs.com/package/cyclic-32)
[](https://npmjs.com/package/cyclic-32)
A tiny, streaming, seedable [CRC32] library, compatible with Node's [crypto.Hash API].
In less than 100 LOC.
[CRC32]: https://en.wikipedia.org/wiki/Cyclic_redundancy_check
[crypto.Hash API]: https://nodejs.org/api/crypto.html#crypto_class_hash
## Install via [npm](https://npmjs.com)
```sh
$ npm install --save cyclic-32
```
## Features
- **Speed:** ~300 MB/s on a 2012 Macbook Air
- **Size:** It's 96 lines of code (plus 22 lines of comments, and 17 blank)
- **Streams:** .pipe().pipe().pipe()
- **Seedable:** If you have more complex things in mind
- **CLI:** Possibly useful for npm run scripts
## Usage
### API
```js
var checksum = crc32( buffer, seed = 0, table = crc32.TABLE.DEFAULT )
```
```js
// Shorthand for Castagnoli
var castagnoli = crc32.c( buffer, seed = 0 )
```
```js
var checksumStream = crc32.createHash({
seed: 0,
table: crc32.TABLE.DEFAULT,
})
```
**Builtin tables:**
- `crc32.TABLE.DEFAULT`: Standard CRC32
- `crc32.TABLE.CASTAGNOLI`: Castagnoli
### Examples
```js
var crc32 = require( 'cyclic-32' )
```
Calculate the CRC32 checksum of a Buffer:
```js
var buffer = new Buffer( 'I shall be summed', 'ascii' )
console.log( crc32( buffer ) ) // -476443423
```
Pass a seed value:
```js
var buffer = new Buffer( 'I shall be summoned', 'ascii' )
console.log( crc32( buffer, 666 ) ) // -823676065
```
Calculate the CRC32 checksum over a Stream:
```js
fs.createReadStream( filename )
.pipe( crc32.createHash() )
.on( 'data', function( buffer ) {
console.log( 'CRC32:', buffer.toString( 'hex' ) )
})
```
If you want to pass an `encoding`, or `seed`:
```js
fs.createReadStream( filename )
.pipe( new crc32.Hash({ encoding: 'hex', seed: -12345678 }) )
.on( 'data', function( checksum ) {
console.log( 'CRC32:', checksum )
})
```
Or, if you'd rather stick to the `crypto.Hash` API:
```js
var hash = crc32.createHash()
hash.update( 'I shall' )
.update( 'be summed' )
console.log( 'CRC32:', hash.digest( 'hex' ) )
```
## CLI Usage
Calculate the checksum of a file:
```sh
$ crc32 filename
0a0ca5aa
```
Pipe stuff into it via stdin:
```sh
$ cat filename | crc32
ffe6bbc0
```