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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 | [](https://travis-ci.org/Cyan4973/lz4) |
|dev | [](https://travis-ci.org/Cyan4973/lz4) |
|visual | [](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.
Direct commit to "master" are not permitted.
> - Feature branches can also exist,
for dedicated tests of larger modifications before merge into "dev" branch.
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
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