diff options
Diffstat (limited to 'other-licenses/7zstub/src/DOC/lzma-sdk.txt')
| -rw-r--r-- | other-licenses/7zstub/src/DOC/lzma-sdk.txt | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/other-licenses/7zstub/src/DOC/lzma-sdk.txt b/other-licenses/7zstub/src/DOC/lzma-sdk.txt new file mode 100644 index 000000000..01521e939 --- /dev/null +++ b/other-licenses/7zstub/src/DOC/lzma-sdk.txt @@ -0,0 +1,357 @@ +LZMA SDK 18.05
+--------------
+
+LZMA SDK provides the documentation, samples, header files,
+libraries, and tools you need to develop applications that
+use 7z / LZMA / LZMA2 / XZ compression.
+
+LZMA is an improved version of famous LZ77 compression algorithm.
+It was improved in way of maximum increasing of compression ratio,
+keeping high decompression speed and low memory requirements for
+decompressing.
+
+LZMA2 is a LZMA based compression method. LZMA2 provides better
+multithreading support for compression than LZMA and some other improvements.
+
+7z is a file format for data compression and file archiving.
+7z is a main file format for 7-Zip compression program (www.7-zip.org).
+7z format supports different compression methods: LZMA, LZMA2 and others.
+7z also supports AES-256 based encryption.
+
+XZ is a file format for data compression that uses LZMA2 compression.
+XZ format provides additional features: SHA/CRC check, filters for
+improved compression ratio, splitting to blocks and streams,
+
+
+
+LICENSE
+-------
+
+LZMA SDK is written and placed in the public domain by Igor Pavlov.
+
+Some code in LZMA SDK is based on public domain code from another developers:
+ 1) PPMd var.H (2001): Dmitry Shkarin
+ 2) SHA-256: Wei Dai (Crypto++ library)
+
+Anyone is free to copy, modify, publish, use, compile, sell, or distribute the
+original LZMA SDK code, either in source code form or as a compiled binary, for
+any purpose, commercial or non-commercial, and by any means.
+
+LZMA SDK code is compatible with open source licenses, for example, you can
+include it to GNU GPL or GNU LGPL code.
+
+
+LZMA SDK Contents
+-----------------
+
+ Source code:
+
+ - C / C++ / C# / Java - LZMA compression and decompression
+ - C / C++ - LZMA2 compression and decompression
+ - C / C++ - XZ compression and decompression
+ - C - 7z decompression
+ - C++ - 7z compression and decompression
+ - C - small SFXs for installers (7z decompression)
+ - C++ - SFXs and SFXs for installers (7z decompression)
+
+ Precomiled binaries:
+
+ - console programs for lzma / 7z / xz compression and decompression
+ - SFX modules for installers.
+
+
+UNIX/Linux version
+------------------
+To compile C++ version of file->file LZMA encoding, go to directory
+CPP/7zip/Bundles/LzmaCon
+and call make to recompile it:
+ make -f makefile.gcc clean all
+
+In some UNIX/Linux versions you must compile LZMA with static libraries.
+To compile with static libraries, you can use
+LIB = -lm -static
+
+Also you can use p7zip (port of 7-Zip for POSIX systems like Unix or Linux):
+
+ http://p7zip.sourceforge.net/
+
+
+Files
+-----
+
+DOC/7zC.txt - 7z ANSI-C Decoder description
+DOC/7zFormat.txt - 7z Format description
+DOC/installer.txt - information about 7-Zip for installers
+DOC/lzma.txt - LZMA compression description
+DOC/lzma-sdk.txt - LZMA SDK description (this file)
+DOC/lzma-history.txt - history of LZMA SDK
+DOC/lzma-specification.txt - Specification of LZMA
+DOC/Methods.txt - Compression method IDs for .7z
+
+bin/installer/ - example script to create installer that uses SFX module,
+
+bin/7zdec.exe - simplified 7z archive decoder
+bin/7zr.exe - 7-Zip console program (reduced version)
+bin/x64/7zr.exe - 7-Zip console program (reduced version) (x64 version)
+bin/lzma.exe - file->file LZMA encoder/decoder for Windows
+bin/7zS2.sfx - small SFX module for installers (GUI version)
+bin/7zS2con.sfx - small SFX module for installers (Console version)
+bin/7zSD.sfx - SFX module for installers.
+
+
+7zDec.exe
+---------
+7zDec.exe is simplified 7z archive decoder.
+It supports only LZMA, LZMA2, and PPMd methods.
+7zDec decodes whole solid block from 7z archive to RAM.
+The RAM consumption can be high.
+
+
+
+
+Source code structure
+---------------------
+
+
+Asm/ - asm files (optimized code for CRC calculation and Intel-AES encryption)
+
+C/ - C files (compression / decompression and other)
+ Util/
+ 7z - 7z decoder program (decoding 7z files)
+ Lzma - LZMA program (file->file LZMA encoder/decoder).
+ LzmaLib - LZMA library (.DLL for Windows)
+ SfxSetup - small SFX module for installers
+
+CPP/ -- CPP files
+
+ Common - common files for C++ projects
+ Windows - common files for Windows related code
+
+ 7zip - files related to 7-Zip
+
+ Archive - files related to archiving
+
+ Common - common files for archive handling
+ 7z - 7z C++ Encoder/Decoder
+
+ Bundles - Modules that are bundles of other modules (files)
+
+ Alone7z - 7zr.exe: Standalone 7-Zip console program (reduced version)
+ Format7zExtractR - 7zxr.dll: Reduced version of 7z DLL: extracting from 7z/LZMA/BCJ/BCJ2.
+ Format7zR - 7zr.dll: Reduced version of 7z DLL: extracting/compressing to 7z/LZMA/BCJ/BCJ2
+ LzmaCon - lzma.exe: LZMA compression/decompression
+ LzmaSpec - example code for LZMA Specification
+ SFXCon - 7zCon.sfx: Console 7z SFX module
+ SFXSetup - 7zS.sfx: 7z SFX module for installers
+ SFXWin - 7z.sfx: GUI 7z SFX module
+
+ Common - common files for 7-Zip
+
+ Compress - files for compression/decompression
+
+ Crypto - files for encryption / decompression
+
+ UI - User Interface files
+
+ Client7z - Test application for 7za.dll, 7zr.dll, 7zxr.dll
+ Common - Common UI files
+ Console - Code for console program (7z.exe)
+ Explorer - Some code from 7-Zip Shell extension
+ FileManager - Some GUI code from 7-Zip File Manager
+ GUI - Some GUI code from 7-Zip
+
+
+CS/ - C# files
+ 7zip
+ Common - some common files for 7-Zip
+ Compress - files related to compression/decompression
+ LZ - files related to LZ (Lempel-Ziv) compression algorithm
+ LZMA - LZMA compression/decompression
+ LzmaAlone - file->file LZMA compression/decompression
+ RangeCoder - Range Coder (special code of compression/decompression)
+
+Java/ - Java files
+ SevenZip
+ Compression - files related to compression/decompression
+ LZ - files related to LZ (Lempel-Ziv) compression algorithm
+ LZMA - LZMA compression/decompression
+ RangeCoder - Range Coder (special code of compression/decompression)
+
+
+Note:
+ Asm / C / C++ source code of LZMA SDK is part of 7-Zip's source code.
+ 7-Zip's source code can be downloaded from 7-Zip's SourceForge page:
+
+ http://sourceforge.net/projects/sevenzip/
+
+
+
+LZMA features
+-------------
+ - Variable dictionary size (up to 1 GB)
+ - Estimated compressing speed: about 2 MB/s on 2 GHz CPU
+ - Estimated decompressing speed:
+ - 20-30 MB/s on modern 2 GHz cpu
+ - 1-2 MB/s on 200 MHz simple RISC cpu: (ARM, MIPS, PowerPC)
+ - Small memory requirements for decompressing (16 KB + DictionarySize)
+ - Small code size for decompressing: 5-8 KB
+
+LZMA decoder uses only integer operations and can be
+implemented in any modern 32-bit CPU (or on 16-bit CPU with some conditions).
+
+Some critical operations that affect the speed of LZMA decompression:
+ 1) 32*16 bit integer multiply
+ 2) Mispredicted branches (penalty mostly depends from pipeline length)
+ 3) 32-bit shift and arithmetic operations
+
+The speed of LZMA decompressing mostly depends from CPU speed.
+Memory speed has no big meaning. But if your CPU has small data cache,
+overall weight of memory speed will slightly increase.
+
+
+How To Use
+----------
+
+Using LZMA encoder/decoder executable
+--------------------------------------
+
+Usage: LZMA <e|d> inputFile outputFile [<switches>...]
+
+ e: encode file
+
+ d: decode file
+
+ b: Benchmark. There are two tests: compressing and decompressing
+ with LZMA method. Benchmark shows rating in MIPS (million
+ instructions per second). Rating value is calculated from
+ measured speed and it is normalized with Intel's Core 2 results.
+ Also Benchmark checks possible hardware errors (RAM
+ errors in most cases). Benchmark uses these settings:
+ (-a1, -d21, -fb32, -mfbt4). You can change only -d parameter.
+ Also you can change the number of iterations. Example for 30 iterations:
+ LZMA b 30
+ Default number of iterations is 10.
+
+<Switches>
+
+
+ -a{N}: set compression mode 0 = fast, 1 = normal
+ default: 1 (normal)
+
+ d{N}: Sets Dictionary size - [0, 30], default: 23 (8MB)
+ The maximum value for dictionary size is 1 GB = 2^30 bytes.
+ Dictionary size is calculated as DictionarySize = 2^N bytes.
+ For decompressing file compressed by LZMA method with dictionary
+ size D = 2^N you need about D bytes of memory (RAM).
+
+ -fb{N}: set number of fast bytes - [5, 273], default: 128
+ Usually big number gives a little bit better compression ratio
+ and slower compression process.
+
+ -lc{N}: set number of literal context bits - [0, 8], default: 3
+ Sometimes lc=4 gives gain for big files.
+
+ -lp{N}: set number of literal pos bits - [0, 4], default: 0
+ lp switch is intended for periodical data when period is
+ equal 2^N. For example, for 32-bit (4 bytes)
+ periodical data you can use lp=2. Often it's better to set lc0,
+ if you change lp switch.
+
+ -pb{N}: set number of pos bits - [0, 4], default: 2
+ pb switch is intended for periodical data
+ when period is equal 2^N.
+
+ -mf{MF_ID}: set Match Finder. Default: bt4.
+ Algorithms from hc* group doesn't provide good compression
+ ratio, but they often works pretty fast in combination with
+ fast mode (-a0).
+
+ Memory requirements depend from dictionary size
+ (parameter "d" in table below).
+
+ MF_ID Memory Description
+
+ bt2 d * 9.5 + 4MB Binary Tree with 2 bytes hashing.
+ bt3 d * 11.5 + 4MB Binary Tree with 3 bytes hashing.
+ bt4 d * 11.5 + 4MB Binary Tree with 4 bytes hashing.
+ hc4 d * 7.5 + 4MB Hash Chain with 4 bytes hashing.
+
+ -eos: write End Of Stream marker. By default LZMA doesn't write
+ eos marker, since LZMA decoder knows uncompressed size
+ stored in .lzma file header.
+
+ -si: Read data from stdin (it will write End Of Stream marker).
+ -so: Write data to stdout
+
+
+Examples:
+
+1) LZMA e file.bin file.lzma -d16 -lc0
+
+compresses file.bin to file.lzma with 64 KB dictionary (2^16=64K)
+and 0 literal context bits. -lc0 allows to reduce memory requirements
+for decompression.
+
+
+2) LZMA e file.bin file.lzma -lc0 -lp2
+
+compresses file.bin to file.lzma with settings suitable
+for 32-bit periodical data (for example, ARM or MIPS code).
+
+3) LZMA d file.lzma file.bin
+
+decompresses file.lzma to file.bin.
+
+
+Compression ratio hints
+-----------------------
+
+Recommendations
+---------------
+
+To increase the compression ratio for LZMA compressing it's desirable
+to have aligned data (if it's possible) and also it's desirable to locate
+data in such order, where code is grouped in one place and data is
+grouped in other place (it's better than such mixing: code, data, code,
+data, ...).
+
+
+Filters
+-------
+You can increase the compression ratio for some data types, using
+special filters before compressing. For example, it's possible to
+increase the compression ratio on 5-10% for code for those CPU ISAs:
+x86, IA-64, ARM, ARM-Thumb, PowerPC, SPARC.
+
+You can find C source code of such filters in C/Bra*.* files
+
+You can check the compression ratio gain of these filters with such
+7-Zip commands (example for ARM code):
+No filter:
+ 7z a a1.7z a.bin -m0=lzma
+
+With filter for little-endian ARM code:
+ 7z a a2.7z a.bin -m0=arm -m1=lzma
+
+It works in such manner:
+Compressing = Filter_encoding + LZMA_encoding
+Decompressing = LZMA_decoding + Filter_decoding
+
+Compressing and decompressing speed of such filters is very high,
+so it will not increase decompressing time too much.
+Moreover, it reduces decompression time for LZMA_decoding,
+since compression ratio with filtering is higher.
+
+These filters convert CALL (calling procedure) instructions
+from relative offsets to absolute addresses, so such data becomes more
+compressible.
+
+For some ISAs (for example, for MIPS) it's impossible to get gain from such filter.
+
+
+
+---
+
+http://www.7-zip.org
+http://www.7-zip.org/sdk.html
+http://www.7-zip.org/support.html
|