README.md

LZ4 - Extremely fast compression
================================

LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s per core, scalable with multi-cores CPU. It also features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems.
A high compression derivative, called LZ4_HC, is also provided. It trades CPU time for compression ratio.

|Branch      |Status   |
|------------|---------|
|master      | [![Build Status](https://travis-ci.org/Cyan4973/lz4.svg?branch=master)](https://travis-ci.org/Cyan4973/lz4) |
|dev         | [![Build Status](https://travis-ci.org/Cyan4973/lz4.svg?branch=dev)](https://travis-ci.org/Cyan4973/lz4) |


> **Branch Policy:**

> - The "master" branch is considered stable, at all times.
> - The "dev" branch is the one where all contributions must be merged before being promoted to master.
>  - If you plan to propose a patch, please commit into the "dev" branch. Direct commit to "master" are not permitted.
> - Feature branches can also exist, for dedicated testing of larger modifications before merge into "dev" branch.

Benchmarks
-------------------------

The benchmark uses the [Open-Source Benchmark program by m^2 (v0.14.2)](http://encode.ru/threads/1371-Filesystem-benchmark?p=33548&viewfull=1#post33548) compiled with GCC v4.6.1 on Linux Ubuntu 64-bits v11.10,
The reference system uses a Core i5-3340M @2.7GHz.
Benchmark evaluates the compression of reference [Silesia Corpus](http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia) in single-thread mode.

<table>
  <tr>
    <th>Compressor</th><th>Ratio</th><th>Compression</th><th>Decompression</th>
  </tr>
  <tr>
    <th>LZ4 (r101)</th><th>2.084</th><th>422 MB/s</th><th>1820 MB/s</th>
  </tr>
  <tr>
    <th>LZO 2.06</th><th>2.106</th><th>414 MB/s</th><th>600 MB/s</th>
  </tr>
  <tr>
    <th>QuickLZ 1.5.1b6</th><th>2.237</th><th>373 MB/s</th><th>420 MB/s</th>
  </tr>
  <tr>
    <th>Snappy 1.1.0</th><th>2.091</th><th>323 MB/s</th><th>1070 MB/s</th>
  </tr>
  <tr>
    <th>LZF</th><th>2.077</th><th>270 MB/s</th><th>570 MB/s</th>
  </tr>
  <tr>
    <th>zlib 1.2.8 -1</th><th>2.730</th><th>65 MB/s</th><th>280 MB/s</th>
  </tr>
  <tr>
    <th>LZ4 HC (r101)</th><th>2.720</th><th>25 MB/s</th><th>2080 MB/s</th>
  </tr>
  <tr>
    <th>zlib 1.2.8 -6</th><th>3.099</th><th>21 MB/s</th><th>300 MB/s</th>
  </tr>
</table>

The LZ4 block compression format is detailed within [lz4_block_format.txt](lz4_block_format.txt).

For streaming unknown amount of data and compress files of any size, a frame format has been published, and can be consulted within the file LZ4_Frame_Format.html .