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) [![Build status](https://ci.appveyor.com/api/projects/status/v6kxv9si529477cq/branch/master?svg=true)](https://ci.appveyor.com/project/YannCollet/lz4) |
|dev         | [![Build Status](https://travis-ci.org/Cyan4973/lz4.svg?branch=dev)](https://travis-ci.org/Cyan4973/lz4) [![Build status](https://ci.appveyor.com/api/projects/status/v6kxv9si529477cq/branch/dev?svg=true)](https://ci.appveyor.com/project/YannCollet/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,
      or its own feature branch.
      Direct commit to "master" are not permitted.

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

The benchmark uses the [Open-Source Benchmark program by m^2 (v0.14.3)]
compiled with GCC v4.8.2 on Linux Mint 64-bits v17.
The reference system uses a Core i5-4300U @1.9GHz.
Benchmark evaluates the compression of reference [Silesia Corpus]
in single-thread mode.

|  Compressor       | Ratio   | Compression | Decompression |
|  ----------       | -----   | ----------- | ------------- |
|  memcpy           |  1.000  | 4200 MB/s   |   4200 MB/s   |
|**LZ4 fast (r129)**|  1.607  |**680 MB/s** | **2220 MB/s** |
|**LZ4 (r129)**     |**2.101**|**385 MB/s** | **1850 MB/s** |
|  LZO 2.06         |  2.108  |  350 MB/s   |    510 MB/s   |
|  QuickLZ 1.5.1.b6 |  2.238  |  320 MB/s   |    380 MB/s   |
|  Snappy 1.1.0     |  2.091  |  250 MB/s   |    960 MB/s   |
|  zlib 1.2.8 -1    |  2.730  |   59 MB/s   |    250 MB/s   |
|**LZ4 HC (r129)**  |**2.720**|   22 MB/s   | **1830 MB/s** |
|  zlib 1.2.8 -6    |  3.099  |   18 MB/s   |    270 MB/s   |

The raw LZ4 block compression format is detailed within [lz4_Block_format].

Compressing an arbitrarily long file or data stream requires multiple blocks.
Organizing these blocks and providing a common header format to handle their content
is the purpose of the Frame format, defined into [lz4_Frame_format].
Interoperable versions of LZ4 must respect this frame format too.

[Open-Source Benchmark program by m^2 (v0.14.3)]: http://encode.ru/threads/1371-Filesystem-benchmark?p=34029&viewfull=1#post34029
[Silesia Corpus]: http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia
[lz4_Block_format]: lz4_Block_format.md
[lz4_Frame_format]: lz4_Frame_format.md