1LZ4 - Extremely fast compression 2================================ 3 4LZ4 is lossless compression algorithm, 5providing compression speed at 400 MB/s per core, 6scalable with multi-cores CPU. 7It features an extremely fast decoder, 8with speed in multiple GB/s per core, 9typically reaching RAM speed limits on multi-core systems. 10 11Speed can be tuned dynamically, selecting an "acceleration" factor 12which trades compression ratio for more speed up. 13On the other end, a high compression derivative, LZ4_HC, is also provided, 14trading CPU time for improved compression ratio. 15All versions feature the same decompression speed. 16 17LZ4 library is provided as open-source software using BSD license.s 18 19 20|Branch |Status | 21|------------|---------| 22|master | [![Build Status][travisMasterBadge]][travisLink] [![Build status][AppveyorMasterBadge]][AppveyorLink] [![coverity][coverBadge]][coverlink] | 23|dev | [![Build Status][travisDevBadge]][travisLink] [![Build status][AppveyorDevBadge]][AppveyorLink] | 24 25[travisMasterBadge]: https://travis-ci.org/Cyan4973/lz4.svg?branch=master "Continuous Integration test suite" 26[travisDevBadge]: https://travis-ci.org/Cyan4973/lz4.svg?branch=dev "Continuous Integration test suite" 27[travisLink]: https://ci.appveyor.com/project/YannCollet/lz4 28[AppveyorMasterBadge]: https://ci.appveyor.com/api/projects/status/v6kxv9si529477cq/branch/master?svg=true "Visual test suite" 29[AppveyorDevBadge]: https://ci.appveyor.com/api/projects/status/v6kxv9si529477cq/branch/dev?svg=true "Visual test suite" 30[AppveyorLink]: https://ci.appveyor.com/project/YannCollet/lz4 31[coverBadge]: https://scan.coverity.com/projects/4735/badge.svg "Static code analysis of Master branch" 32[coverlink]: https://scan.coverity.com/projects/4735 33 34> **Branch Policy:** 35 36> - The "master" branch is considered stable, at all times. 37> - The "dev" branch is the one where all contributions must be merged 38 before being promoted to master. 39> + If you plan to propose a patch, please commit into the "dev" branch, 40 or its own feature branch. 41 Direct commit to "master" are not permitted. 42 43Benchmarks 44------------------------- 45 46The benchmark uses the [Open-Source Benchmark program by m^2 (v0.14.3)] 47compiled with GCC v4.8.2 on Linux Mint 64-bits v17. 48The reference system uses a Core i5-4300U @1.9GHz. 49Benchmark evaluates the compression of reference [Silesia Corpus] 50in single-thread mode. 51 52| Compressor | Ratio | Compression | Decompression | 53| ---------- | ----- | ----------- | ------------- | 54| memcpy | 1.000 | 4200 MB/s | 4200 MB/s | 55|**LZ4 fast 17 (r129)**| 1.607 |**690 MB/s** | **2220 MB/s** | 56|**LZ4 default (r129)**|**2.101**|**385 MB/s** | **1850 MB/s** | 57| LZO 2.06 | 2.108 | 350 MB/s | 510 MB/s | 58| QuickLZ 1.5.1.b6 | 2.238 | 320 MB/s | 380 MB/s | 59| Snappy 1.1.0 | 2.091 | 250 MB/s | 960 MB/s | 60| LZF v3.6 | 2.073 | 175 MB/s | 500 MB/s | 61| zlib 1.2.8 -1 | 2.730 | 59 MB/s | 250 MB/s | 62|**LZ4 HC (r129)** |**2.720**| 22 MB/s | **1830 MB/s** | 63| zlib 1.2.8 -6 | 3.099 | 18 MB/s | 270 MB/s | 64 65 66Documentation 67------------------------- 68 69The raw LZ4 block compression format is detailed within [lz4_Block_format]. 70 71To compress an arbitrarily long file or data stream, multiple blocks are required. 72Organizing these blocks and providing a common header format to handle their content 73is the purpose of the Frame format, defined into [lz4_Frame_format]. 74Interoperable versions of LZ4 must respect this frame format. 75 76 77Other source versions 78------------------------- 79 80Beyond the C reference source, 81many contributors have created versions of lz4 in multiple languages 82(Java, C#, Python, Perl, Ruby, etc.). 83A list of known source ports is maintained on the [LZ4 Homepage]. 84 85 86[Open-Source Benchmark program by m^2 (v0.14.3)]: http://encode.ru/threads/1371-Filesystem-benchmark?p=34029&viewfull=1#post34029 87[Silesia Corpus]: http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia 88[lz4_Block_format]: lz4_Block_format.md 89[lz4_Frame_format]: lz4_Frame_format.md 90[LZ4 Homepage]: http://www.lz4.org 91
