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diff --git a/util/cbfstool/lz4/README.md b/util/cbfstool/lz4/README.md new file mode 100644 index 0000000000..d992f2819d --- /dev/null +++ b/util/cbfstool/lz4/README.md @@ -0,0 +1,90 @@ +LZ4 - Extremely fast compression +================================ + +LZ4 is lossless compression algorithm, +providing compression speed at 400 MB/s per core, +scalable with multi-cores CPU. +It features an extremely fast decoder, +with speed in multiple GB/s per core, +typically reaching RAM speed limits on multi-core systems. + +Speed can be tuned dynamically, selecting an "acceleration" factor +which trades compression ratio for more speed up. +On the other end, a high compression derivative, LZ4_HC, is also provided, +trading CPU time for improved compression ratio. +All versions feature the same decompression speed. + +LZ4 library is provided as open-source software using BSD license.s + + +|Branch |Status | +|------------|---------| +|master | [![Build Status][travisMasterBadge]][travisLink] [![Build status][AppveyorMasterBadge]][AppveyorLink] [![coverity][coverBadge]][coverlink] | +|dev | [![Build Status][travisDevBadge]][travisLink] [![Build status][AppveyorDevBadge]][AppveyorLink] | + +[travisMasterBadge]: https://travis-ci.org/Cyan4973/lz4.svg?branch=master "Continuous Integration test suite" +[travisDevBadge]: https://travis-ci.org/Cyan4973/lz4.svg?branch=dev "Continuous Integration test suite" +[travisLink]: https://ci.appveyor.com/project/YannCollet/lz4 +[AppveyorMasterBadge]: https://ci.appveyor.com/api/projects/status/v6kxv9si529477cq/branch/master?svg=true "Visual test suite" +[AppveyorDevBadge]: https://ci.appveyor.com/api/projects/status/v6kxv9si529477cq/branch/dev?svg=true "Visual test suite" +[AppveyorLink]: https://ci.appveyor.com/project/YannCollet/lz4 +[coverBadge]: https://scan.coverity.com/projects/4735/badge.svg "Static code analysis of Master branch" +[coverlink]: https://scan.coverity.com/projects/4735 + +> **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 17 (r129)**| 1.607 |**690 MB/s** | **2220 MB/s** | +|**LZ4 default (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 | +| LZF v3.6 | 2.073 | 175 MB/s | 500 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 | + + +Documentation +------------------------- + +The raw LZ4 block compression format is detailed within [lz4_Block_format]. + +To compress an arbitrarily long file or data stream, multiple blocks are required. +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. + + +Other source versions +------------------------- + +Beyond the C reference source, +many contributors have created versions of lz4 in multiple languages +(Java, C#, Python, Perl, Ruby, etc.). +A list of known source ports is maintained on the [LZ4 Homepage]. + + +[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 +[LZ4 Homepage]: http://www.lz4.org |