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 2-Clause license. 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/lz4/lz4.svg?branch=master "Continuous Integration test suite" 26[travisDevBadge]: https://travis-ci.org/lz4/lz4.svg?branch=dev "Continuous Integration test suite" 27[travisLink]: https://travis-ci.org/lz4/lz4 28[AppveyorMasterBadge]: https://ci.appveyor.com/api/projects/status/jc2yhgwyc7qqtsko/branch/master?svg=true "Windows test suite" 29[AppveyorDevBadge]: https://ci.appveyor.com/api/projects/status/jc2yhgwyc7qqtsko/branch/dev?svg=true "Windows test suite" 30[AppveyorLink]: https://ci.appveyor.com/project/YannCollet/lz4-1lndh 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 [lzbench], from @inikep 47compiled with GCC v6.2.0 on Linux 64-bits. 48The reference system uses a Core i7-3930K CPU @ 4.5GHz. 49Benchmark evaluates the compression of reference [Silesia Corpus] 50in single-thread mode. 51 52[lzbench]: https://github.com/inikep/lzbench 53[Silesia Corpus]: http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia 54 55| Compressor | Ratio | Compression | Decompression | 56| ---------- | ----- | ----------- | ------------- | 57| memcpy | 1.000 | 7300 MB/s | 7300 MB/s | 58|**LZ4 fast 8 (v1.7.3)**| 1.799 |**911 MB/s** | **3360 MB/s** | 59|**LZ4 default (v1.7.3)**|**2.101**|**625 MB/s** | **3220 MB/s** | 60| LZO 2.09 | 2.108 | 620 MB/s | 845 MB/s | 61| QuickLZ 1.5.0 | 2.238 | 510 MB/s | 600 MB/s | 62| Snappy 1.1.3 | 2.091 | 450 MB/s | 1550 MB/s | 63| LZF v3.6 | 2.073 | 365 MB/s | 820 MB/s | 64| [Zstandard] 1.1.1 -1 | 2.876 | 330 MB/s | 930 MB/s | 65| [Zstandard] 1.1.1 -3 | 3.164 | 200 MB/s | 810 MB/s | 66| [zlib] deflate 1.2.8 -1| 2.730 | 100 MB/s | 370 MB/s | 67|**LZ4 HC -9 (v1.7.3)** |**2.720**| 34 MB/s | **3240 MB/s** | 68| [zlib] deflate 1.2.8 -6| 3.099 | 33 MB/s | 390 MB/s | 69 70[zlib]: http://www.zlib.net/ 71[Zstandard]: http://www.zstd.net/ 72 73LZ4 is also compatible and well optimized for x32 mode, for which it provides +10% speed performance. 74 75 76Documentation 77------------------------- 78 79The raw LZ4 block compression format is detailed within [lz4_Block_format]. 80 81To compress an arbitrarily long file or data stream, multiple blocks are required. 82Organizing these blocks and providing a common header format to handle their content 83is the purpose of the Frame format, defined into [lz4_Frame_format]. 84Interoperable versions of LZ4 must respect this frame format. 85 86[lz4_Block_format]: doc/lz4_Block_format.md 87[lz4_Frame_format]: doc/lz4_Frame_format.md 88 89 90Other source versions 91------------------------- 92 93Beyond the C reference source, 94many contributors have created versions of lz4 in multiple languages 95(Java, C#, Python, Perl, Ruby, etc.). 96A list of known source ports is maintained on the [LZ4 Homepage]. 97 98[LZ4 Homepage]: http://www.lz4.org 99