README.md - lz4 - Rivoreo Source Code Repositories

 LZ4 - Extremely fast compression
 ================================

 LZ4 is lossless compression algorithm,
 providing compression speed > 500 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 faster speed.
 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 is also compatible with [dictionary compression](https://github.com/facebook/zstd#the-case-for-small-data-compression),
 both at [API](https://github.com/lz4/lz4/blob/v1.8.3/lib/lz4frame.h#L481) and [CLI](https://github.com/lz4/lz4/blob/v1.8.3/programs/lz4.1.md#operation-modifiers) levels.
 It can ingest any input file as dictionary, though only the final 64KB are used.
 This capability can be combined with the [Zstandard Dictionary Builder](https://github.com/facebook/zstd/blob/v1.3.5/programs/zstd.1.md#dictionary-builder),
 in order to drastically improve compression performance on small files.


 LZ4 library is provided as open-source software using BSD 2-Clause license.


 |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/lz4/lz4.svg?branch=master "Continuous Integration test suite"
 [travisDevBadge]: https://travis-ci.org/lz4/lz4.svg?branch=dev "Continuous Integration test suite"
 [travisLink]: https://travis-ci.org/lz4/lz4
 [AppveyorMasterBadge]: https://ci.appveyor.com/api/projects/status/github/lz4/lz4?branch=master&svg=true "Windows test suite"
 [AppveyorDevBadge]: https://ci.appveyor.com/api/projects/status/github/lz4/lz4?branch=dev&svg=true "Windows test suite"
 [AppveyorLink]: https://ci.appveyor.com/project/YannCollet/lz4-1lndh
 [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 [lzbench], from @inikep
 compiled with GCC v8.2.0 on Linux 64-bits (Ubuntu 4.18.0-17).
 The reference system uses a Core i7-9700K CPU @ 4.9GHz (w/ turbo boost).
 Benchmark evaluates the compression of reference [Silesia Corpus]
 in single-thread mode.

 [lzbench]: https://github.com/inikep/lzbench
 [Silesia Corpus]: http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia

 |  Compressor             | Ratio   | Compression | Decompression |
 |  ----------             | -----   | ----------- | ------------- |
 |  memcpy                 |  1.000  | 13700 MB/s  |  13700 MB/s   |
 |**LZ4 default (v1.9.0)** |**2.101**| **780 MB/s**| **4970 MB/s** |
 |  LZO 2.09               |  2.108  |   670 MB/s  |    860 MB/s   |
 |  QuickLZ 1.5.0          |  2.238  |   575 MB/s  |    780 MB/s   |
 |  Snappy 1.1.4           |  2.091  |   565 MB/s  |   1950 MB/s   |
 | [Zstandard] 1.4.0 -1    |  2.883  |   515 MB/s  |   1380 MB/s   |
 |  LZF v3.6               |  2.073  |   415 MB/s  |    910 MB/s   |
 | [zlib] deflate 1.2.11 -1|  2.730  |   100 MB/s  |    415 MB/s   |
 |**LZ4 HC -9 (v1.9.0)**   |**2.721**|    41 MB/s  | **4900 MB/s** |
 | [zlib] deflate 1.2.11 -6|  3.099  |    36 MB/s  |    445 MB/s   |

 [zlib]: http://www.zlib.net/
 [Zstandard]: http://www.zstd.net/

 LZ4 is also compatible and optimized for x32 mode,
 for which it provides additional speed performance.


 Installation
 -------------------------

 ```
 make
 make install     # this command may require root permissions
 ```

 LZ4's `Makefile` supports standard [Makefile conventions],
 including [staged installs], [redirection], or [command redefinition].
 It is compatible with parallel builds (`-j#`).

 [Makefile conventions]: https://www.gnu.org/prep/standards/html_node/Makefile-Conventions.html
 [staged installs]: https://www.gnu.org/prep/standards/html_node/DESTDIR.html
 [redirection]: https://www.gnu.org/prep/standards/html_node/Directory-Variables.html
 [command redefinition]: https://www.gnu.org/prep/standards/html_node/Utilities-in-Makefiles.html


 Documentation
 -------------------------

 The raw LZ4 block compression format is detailed within [lz4_Block_format].

 Arbitrarily long files or data streams are compressed using multiple blocks,
 for streaming requirements. These blocks are organized into a frame,
 defined into [lz4_Frame_format].
 Interoperable versions of LZ4 must also respect the frame format.

 [lz4_Block_format]: doc/lz4_Block_format.md
 [lz4_Frame_format]: doc/lz4_Frame_format.md


 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].

 [LZ4 Homepage]: http://www.lz4.org
	LZ4 - Extremely fast compression
	================================

	LZ4 is lossless compression algorithm,
	providing compression speed > 500 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 faster speed.
	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 is also compatible with [dictionary compression](https://github.com/facebook/zstd#the-case-for-small-data-compression),
	both at [API](https://github.com/lz4/lz4/blob/v1.8.3/lib/lz4frame.h#L481) and [CLI](https://github.com/lz4/lz4/blob/v1.8.3/programs/lz4.1.md#operation-modifiers) levels.
	It can ingest any input file as dictionary, though only the final 64KB are used.
	This capability can be combined with the [Zstandard Dictionary Builder](https://github.com/facebook/zstd/blob/v1.3.5/programs/zstd.1.md#dictionary-builder),
	in order to drastically improve compression performance on small files.


	LZ4 library is provided as open-source software using BSD 2-Clause license.


	\|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/lz4/lz4.svg?branch=master "Continuous Integration test suite"
	[travisDevBadge]: https://travis-ci.org/lz4/lz4.svg?branch=dev "Continuous Integration test suite"
	[travisLink]: https://travis-ci.org/lz4/lz4
	[AppveyorMasterBadge]: https://ci.appveyor.com/api/projects/status/github/lz4/lz4?branch=master&svg=true "Windows test suite"
	[AppveyorDevBadge]: https://ci.appveyor.com/api/projects/status/github/lz4/lz4?branch=dev&svg=true "Windows test suite"
	[AppveyorLink]: https://ci.appveyor.com/project/YannCollet/lz4-1lndh
	[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 [lzbench], from @inikep
	compiled with GCC v8.2.0 on Linux 64-bits (Ubuntu 4.18.0-17).
	The reference system uses a Core i7-9700K CPU @ 4.9GHz (w/ turbo boost).
	Benchmark evaluates the compression of reference [Silesia Corpus]
	in single-thread mode.

	[lzbench]: https://github.com/inikep/lzbench
	[Silesia Corpus]: http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia

	\| Compressor \| Ratio \| Compression \| Decompression \|
	\| ---------- \| ----- \| ----------- \| ------------- \|
	\| memcpy \| 1.000 \| 13700 MB/s \| 13700 MB/s \|
	\|LZ4 default (v1.9.0) \|2.101\| 780 MB/s\| 4970 MB/s \|
	\| LZO 2.09 \| 2.108 \| 670 MB/s \| 860 MB/s \|
	\| QuickLZ 1.5.0 \| 2.238 \| 575 MB/s \| 780 MB/s \|
	\| Snappy 1.1.4 \| 2.091 \| 565 MB/s \| 1950 MB/s \|
	\| [Zstandard] 1.4.0 -1 \| 2.883 \| 515 MB/s \| 1380 MB/s \|
	\| LZF v3.6 \| 2.073 \| 415 MB/s \| 910 MB/s \|
	\| [zlib] deflate 1.2.11 -1\| 2.730 \| 100 MB/s \| 415 MB/s \|
	\|LZ4 HC -9 (v1.9.0) \|2.721\| 41 MB/s \| 4900 MB/s \|
	\| [zlib] deflate 1.2.11 -6\| 3.099 \| 36 MB/s \| 445 MB/s \|

	[zlib]: http://www.zlib.net/
	[Zstandard]: http://www.zstd.net/

	LZ4 is also compatible and optimized for x32 mode,
	for which it provides additional speed performance.


	Installation
	-------------------------

	```
	make
	make install # this command may require root permissions
	```

	LZ4's `Makefile` supports standard [Makefile conventions],
	including [staged installs], [redirection], or [command redefinition].
	It is compatible with parallel builds (`-j#`).

	[Makefile conventions]: https://www.gnu.org/prep/standards/html_node/Makefile-Conventions.html
	[staged installs]: https://www.gnu.org/prep/standards/html_node/DESTDIR.html
	[redirection]: https://www.gnu.org/prep/standards/html_node/Directory-Variables.html
	[command redefinition]: https://www.gnu.org/prep/standards/html_node/Utilities-in-Makefiles.html


	Documentation
	-------------------------

	The raw LZ4 block compression format is detailed within [lz4_Block_format].

	Arbitrarily long files or data streams are compressed using multiple blocks,
	for streaming requirements. These blocks are organized into a frame,
	defined into [lz4_Frame_format].
	Interoperable versions of LZ4 must also respect the frame format.

	[lz4_Block_format]: doc/lz4_Block_format.md
	[lz4_Frame_format]: doc/lz4_Frame_format.md


	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].

	[LZ4 Homepage]: http://www.lz4.org