js-crc32/README.md

64 lines
2.0 KiB
Markdown
Raw Normal View History

2014-06-16 21:27:47 +00:00
# crc32
Standard CRC-32 algorithm implementation in JS (for the browser and nodejs).
Emphasis on correctness and performance.
## Installation
In [nodejs](https://www.npmjs.org/package/crc-32):
npm install crc-32
In the browser:
<script lang="javascript" src="crc32.js"></script>
The browser exposes a variable CRC32
## Usage
- `CRC32.buf(byte array or buffer)` assumes the argument is a set of 8 bit
unsigned integers (e.g. nodejs `Buffer` or simple array of ints)
- `CRC32.bstr(binary string)` interprets the argument as a binary string where
the `i`-th byte is `str.charCodeAt(i)`
- `CRC32.str(string)` interprets the argument as a standard JS string
## Testing
`make test` will run the nodejs-based test. To run the in-browser tests, run a
local server and go to the `ctest` directory. To update the browser artifacts,
run `make ctest`.
## Performance
`make perf` will run algorithmic performance tests (which should justify certain
decisions in the code).
`make perf-all` compares the performance of various crc-32 algorithms that
implement the correct form (note that the SSE intrinsic is designed for the
CRC32C checksum and uses a different polynomial).
2014-06-16 21:27:47 +00:00
2014-06-16 21:34:13 +00:00
Unexpected code patterns were based on performance testing in node and browser:
- [Loop unrolling helps!](http://jsperf.com/crc32-table/2)
2014-06-16 21:27:47 +00:00
## In the future ...
- Specifying an arbitrary initial CRC value
- Supporting different polynomials (e.g. CRC32C)
## License
Please consult the attached LICENSE file for details. All rights not explicitly
granted by the Apache 2.0 license are reserved by the Original Author.
[![Build Status](https://travis-ci.org/SheetJS/js-crc32.svg?branch=master)](https://travis-ci.org/SheetJS/js-crc32)
2014-06-16 21:27:47 +00:00
[![Coverage Status](https://coveralls.io/repos/SheetJS/js-crc32/badge.png?branch=master)](https://coveralls.io/r/SheetJS/js-crc32?branch=master)
[![githalytics.com alpha](https://cruel-carlota.pagodabox.com/ee0e89f8b1d5b861ffbf264b8ce329a6 "githalytics.com")](http://githalytics.com/SheetJS/js-crc32)