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coreboot-libre-fam15h-rdimm/util/cbfstool/lz4/README.md

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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 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 Build status coverity
dev Build Status Build status

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.