| commit | 883ebdcee0aae3e8339dd3658c794ca49dfb18b1 | [log] [download] |
|---|---|---|
| author | Dmitry V. Levin <ldv@altlinux.org> | Fri Mar 10 23:35:30 2017 +0000 |
| committer | Dmitry V. Levin <ldv@altlinux.org> | Fri Mar 10 23:35:30 2017 +0000 |
| tree | c40053e00ef1813960436dffb1fde868910b6837 | |
| parent | 25b243588585b06a2d947372284cbfe00da930e9 [diff] |
Export only those symbols that are part of public API Specify -fvisibility=hidden parameter when linking the shared library using -fPIC, assuming that gcc >= 4 is used. This change results to unexporting of the following 42 functions: LZ4F_getErrorCode LZ4_XXH32 LZ4_XXH32_canonicalFromHash LZ4_XXH32_copyState LZ4_XXH32_createState LZ4_XXH32_digest LZ4_XXH32_freeState LZ4_XXH32_hashFromCanonical LZ4_XXH32_reset LZ4_XXH32_update LZ4_XXH64 LZ4_XXH64_canonicalFromHash LZ4_XXH64_copyState LZ4_XXH64_createState LZ4_XXH64_digest LZ4_XXH64_freeState LZ4_XXH64_hashFromCanonical LZ4_XXH64_reset LZ4_XXH64_update LZ4_XXH_versionNumber LZ4_compressHC LZ4_compressHC2 LZ4_compressHC2_continue LZ4_compressHC2_limitedOutput LZ4_compressHC2_limitedOutput_continue LZ4_compressHC2_limitedOutput_withStateHC LZ4_compressHC2_withStateHC LZ4_compressHC_continue LZ4_compressHC_limitedOutput LZ4_compressHC_limitedOutput_continue LZ4_compressHC_limitedOutput_withStateHC LZ4_compressHC_withStateHC LZ4_compress_fast_force LZ4_compress_forceExtDict LZ4_createHC LZ4_decompress_safe_forceExtDict LZ4_freeHC LZ4_resetStreamStateHC LZ4_sizeofStreamStateHC LZ4_slideInputBufferHC LZ4_uncompress LZ4_uncompress_unknownOutputSize
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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 2-Clause license.
| Branch | Status |
|---|---|
| master |   |
| dev |  |
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 lzbench, from @inikep compiled with GCC v6.2.0 on Linux 64-bits. The reference system uses a Core i7-3930K CPU @ 4.5GHz. Benchmark evaluates the compression of reference Silesia Corpus in single-thread mode.
| Compressor | Ratio | Compression | Decompression |
|---|---|---|---|
| memcpy | 1.000 | 7300 MB/s | 7300 MB/s |
| LZ4 fast 8 (v1.7.3) | 1.799 | 911 MB/s | 3360 MB/s |
| LZ4 default (v1.7.3) | 2.101 | 625 MB/s | 3220 MB/s |
| LZO 2.09 | 2.108 | 620 MB/s | 845 MB/s |
| QuickLZ 1.5.0 | 2.238 | 510 MB/s | 600 MB/s |
| Snappy 1.1.3 | 2.091 | 450 MB/s | 1550 MB/s |
| LZF v3.6 | 2.073 | 365 MB/s | 820 MB/s |
| Zstandard 1.1.1 -1 | 2.876 | 330 MB/s | 930 MB/s |
| Zstandard 1.1.1 -3 | 3.164 | 200 MB/s | 810 MB/s |
| zlib deflate 1.2.8 -1 | 2.730 | 100 MB/s | 370 MB/s |
| LZ4 HC -9 (v1.7.3) | 2.720 | 34 MB/s | 3240 MB/s |
| zlib deflate 1.2.8 -6 | 3.099 | 33 MB/s | 390 MB/s |
LZ4 is also compatible and well optimized for x32 mode, for which it provides +10% speed performance.
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.