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Diffstat (limited to 'src/VBox/Devices/EFI/Firmware/MdeModulePkg/Library/LzmaCustomDecompressLib/Sdk/DOC')
2 files changed, 803 insertions, 0 deletions
diff --git a/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Library/LzmaCustomDecompressLib/Sdk/DOC/lzma-history.txt b/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Library/LzmaCustomDecompressLib/Sdk/DOC/lzma-history.txt new file mode 100644 index 00000000..5990cf76 --- /dev/null +++ b/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Library/LzmaCustomDecompressLib/Sdk/DOC/lzma-history.txt @@ -0,0 +1,446 @@ +HISTORY of the LZMA SDK +----------------------- + +19.00 2019-02-21 +------------------------- +- Encryption strength for 7z archives was increased: + the size of random initialization vector was increased from 64-bit to 128-bit, + and the pseudo-random number generator was improved. +- The bug in 7zIn.c code was fixed. + + +18.06 2018-12-30 +------------------------- +- The speed for LZMA/LZMA2 compressing was increased by 3-10%, + and there are minor changes in compression ratio. +- Some bugs were fixed. +- The bug in 7-Zip 18.02-18.05 was fixed: + There was memory leak in multithreading xz decoder - XzDecMt_Decode(), + if xz stream contains only one block. +- The changes for MSVS compiler makefiles: + - the makefiles now use "PLATFORM" macroname with values (x64, x86, arm64) + instead of "CPU" macroname with values (AMD64, ARM64). + - the makefiles by default now use static version of the run-time library. + + +18.05 2018-04-30 +------------------------- +- The speed for LZMA/LZMA2 compressing was increased + by 8% for fastest/fast compression levels and + by 3% for normal/maximum compression levels. +- Previous versions of 7-Zip could work incorrectly in "Large memory pages" mode in + Windows 10 because of some BUG with "Large Pages" in Windows 10. + Now 7-Zip doesn't use "Large Pages" on Windows 10 up to revision 1709 (16299). +- The BUG was fixed in Lzma2Enc.c + Lzma2Enc_Encode2() function worked incorretly, + if (inStream == NULL) and the number of block threads is more than 1. + + +18.03 beta 2018-03-04 +------------------------- +- Asm\x86\LzmaDecOpt.asm: new optimized LZMA decoder written in asm + for x64 with about 30% higher speed than main version of LZMA decoder written in C. +- The speed for single-thread LZMA/LZMA2 decoder written in C was increased by 3%. +- 7-Zip now can use multi-threading for 7z/LZMA2 decoding, + if there are multiple independent data chunks in LZMA2 stream. +- 7-Zip now can use multi-threading for xz decoding, + if there are multiple blocks in xz stream. + + +18.01 2019-01-28 +------------------------- +- The BUG in 17.01 - 18.00 beta was fixed: + XzDec.c : random block unpacking and XzUnpacker_IsBlockFinished() + didn't work correctly for xz archives without checksum (CRC). + + +18.00 beta 2019-01-10 +------------------------- +- The BUG in xz encoder was fixed: + There was memory leak of 16 KB for each file compressed with + xz compression method, if additional filter was used. + + +17.01 beta 2017-08-28 +------------------------- +- Minor speed optimization for LZMA2 (xz and 7z) multi-threading compression. + 7-Zip now uses additional memory buffers for multi-block LZMA2 compression. + CPU utilization was slightly improved. +- 7-zip now creates multi-block xz archives by default. Block size can be + specified with -ms[Size]{m|g} switch. +- xz decoder now can unpack random block from multi-block xz archives. +- 7-Zip command line: @listfile now doesn't work after -- switch. + Use -i@listfile before -- switch instead. +- The BUGs were fixed: + 7-Zip 17.00 beta crashed for commands that write anti-item to 7z archive. + + +17.00 beta 2017-04-29 +------------------------- +- NewHandler.h / NewHandler.cpp: + now it redefines operator new() only for old MSVC compilers (_MSC_VER < 1900). +- C/7zTypes.h : the names of variables in interface structures were changed (vt). +- Some bugs were fixed. 7-Zip could crash in some cases. +- Some internal changes in code. + + +16.04 2016-10-04 +------------------------- +- The bug was fixed in DllSecur.c. + + +16.03 2016-09-28 +------------------------- +- SFX modules now use some protection against DLL preloading attack. +- Some bugs in 7z code were fixed. + + +16.02 2016-05-21 +------------------------- +- The BUG in 16.00 - 16.01 was fixed: + Split Handler (SplitHandler.cpp) returned incorrect + total size value (kpidSize) for split archives. + + +16.01 2016-05-19 +------------------------- +- Some internal changes to reduce the number of compiler warnings. + + +16.00 2016-05-10 +------------------------- +- Some bugs were fixed. + + +15.12 2015-11-19 +------------------------- +- The BUG in C version of 7z decoder was fixed: + 7zDec.c : SzDecodeLzma2() + 7z decoder could mistakenly report about decoding error for some 7z archives + that use LZMA2 compression method. + The probability to get that mistaken decoding error report was about + one error per 16384 solid blocks for solid blocks larger than 16 KB (compressed size). +- The BUG (in 9.26-15.11) in C version of 7z decoder was fixed: + 7zArcIn.c : SzReadHeader2() + 7z decoder worked incorrectly for 7z archives that contain + empty solid blocks, that can be placed to 7z archive, if some file is + unavailable for reading during archive creation. + + +15.09 beta 2015-10-16 +------------------------- +- The BUG in LZMA / LZMA2 encoding code was fixed. + The BUG in LzFind.c::MatchFinder_ReadBlock() function. + If input data size is larger than (4 GiB - dictionary_size), + the following code worked incorrectly: + - LZMA : LzmaEnc_MemEncode(), LzmaEncode() : LZMA encoding functions + for compressing from memory to memory. + That BUG is not related to LZMA encoder version that works via streams. + - LZMA2 : multi-threaded version of LZMA2 encoder worked incorrectly, if + default value of chunk size (CLzma2EncProps::blockSize) is changed + to value larger than (4 GiB - dictionary_size). + + +9.38 beta 2015-01-03 +------------------------- +- The BUG in 9.31-9.37 was fixed: + IArchiveGetRawProps interface was disabled for 7z archives. +- The BUG in 9.26-9.36 was fixed: + Some code in CPP\7zip\Archive\7z\ worked correctly only under Windows. + + +9.36 beta 2014-12-26 +------------------------- +- The BUG in command line version was fixed: + 7-Zip created temporary archive in current folder during update archive + operation, if -w{Path} switch was not specified. + The fixed 7-Zip creates temporary archive in folder that contains updated archive. +- The BUG in 9.33-9.35 was fixed: + 7-Zip silently ignored file reading errors during 7z or gz archive creation, + and the created archive contained only part of file that was read before error. + The fixed 7-Zip stops archive creation and it reports about error. + + +9.35 beta 2014-12-07 +------------------------- +- 7zr.exe now support AES encryption. +- SFX mudules were added to LZMA SDK +- Some bugs were fixed. + + +9.21 beta 2011-04-11 +------------------------- +- New class FString for file names at file systems. +- Speed optimization in CRC code for big-endian CPUs. +- The BUG in Lzma2Dec.c was fixed: + Lzma2Decode function didn't work. + + +9.18 beta 2010-11-02 +------------------------- +- New small SFX module for installers (SfxSetup). + + +9.12 beta 2010-03-24 +------------------------- +- The BUG in LZMA SDK 9.* was fixed: LZMA2 codec didn't work, + if more than 10 threads were used (or more than 20 threads in some modes). + + +9.11 beta 2010-03-15 +------------------------- +- PPMd compression method support + + +9.09 2009-12-12 +------------------------- +- The bug was fixed: + Utf16_To_Utf8 funstions in UTFConvert.cpp and 7zMain.c + incorrectly converted surrogate characters (the code >= 0x10000) to UTF-8. +- Some bugs were fixed + + +9.06 2009-08-17 +------------------------- +- Some changes in ANSI-C 7z Decoder interfaces. + + +9.04 2009-05-30 +------------------------- +- LZMA2 compression method support +- xz format support + + +4.65 2009-02-03 +------------------------- +- Some minor fixes + + +4.63 2008-12-31 +------------------------- +- Some minor fixes + + +4.61 beta 2008-11-23 +------------------------- +- The bug in ANSI-C LZMA Decoder was fixed: + If encoded stream was corrupted, decoder could access memory + outside of allocated range. +- Some changes in ANSI-C 7z Decoder interfaces. +- LZMA SDK is placed in the public domain. + + +4.60 beta 2008-08-19 +------------------------- +- Some minor fixes. + + +4.59 beta 2008-08-13 +------------------------- +- The bug was fixed: + LZMA Encoder in fast compression mode could access memory outside of + allocated range in some rare cases. + + +4.58 beta 2008-05-05 +------------------------- +- ANSI-C LZMA Decoder was rewritten for speed optimizations. +- ANSI-C LZMA Encoder was included to LZMA SDK. +- C++ LZMA code now is just wrapper over ANSI-C code. + + +4.57 2007-12-12 +------------------------- +- Speed optimizations in ?++ LZMA Decoder. +- Small changes for more compatibility with some C/C++ compilers. + + +4.49 beta 2007-07-05 +------------------------- +- .7z ANSI-C Decoder: + - now it supports BCJ and BCJ2 filters + - now it supports files larger than 4 GB. + - now it supports "Last Write Time" field for files. +- C++ code for .7z archives compressing/decompressing from 7-zip + was included to LZMA SDK. + + +4.43 2006-06-04 +------------------------- +- Small changes for more compatibility with some C/C++ compilers. + + +4.42 2006-05-15 +------------------------- +- Small changes in .h files in ANSI-C version. + + +4.39 beta 2006-04-14 +------------------------- +- The bug in versions 4.33b:4.38b was fixed: + C++ version of LZMA encoder could not correctly compress + files larger than 2 GB with HC4 match finder (-mfhc4). + + +4.37 beta 2005-04-06 +------------------------- +- Fixes in C++ code: code could no be compiled if _NO_EXCEPTIONS was defined. + + +4.35 beta 2005-03-02 +------------------------- +- The bug was fixed in C++ version of LZMA Decoder: + If encoded stream was corrupted, decoder could access memory + outside of allocated range. + + +4.34 beta 2006-02-27 +------------------------- +- Compressing speed and memory requirements for compressing were increased +- LZMA now can use only these match finders: HC4, BT2, BT3, BT4 + + +4.32 2005-12-09 +------------------------- +- Java version of LZMA SDK was included + + +4.30 2005-11-20 +------------------------- +- Compression ratio was improved in -a2 mode +- Speed optimizations for compressing in -a2 mode +- -fb switch now supports values up to 273 +- The bug in 7z_C (7zIn.c) was fixed: + It used Alloc/Free functions from different memory pools. + So if program used two memory pools, it worked incorrectly. +- 7z_C: .7z format supporting was improved +- LZMA# SDK (C#.NET version) was included + + +4.27 (Updated) 2005-09-21 +------------------------- +- Some GUIDs/interfaces in C++ were changed. + IStream.h: + ISequentialInStream::Read now works as old ReadPart + ISequentialOutStream::Write now works as old WritePart + + +4.27 2005-08-07 +------------------------- +- The bug in LzmaDecodeSize.c was fixed: + if _LZMA_IN_CB and _LZMA_OUT_READ were defined, + decompressing worked incorrectly. + + +4.26 2005-08-05 +------------------------- +- Fixes in 7z_C code and LzmaTest.c: + previous versions could work incorrectly, + if malloc(0) returns 0 + + +4.23 2005-06-29 +------------------------- +- Small fixes in C++ code + + +4.22 2005-06-10 +------------------------- +- Small fixes + + +4.21 2005-06-08 +------------------------- +- Interfaces for ANSI-C LZMA Decoder (LzmaDecode.c) were changed +- New additional version of ANSI-C LZMA Decoder with zlib-like interface: + - LzmaStateDecode.h + - LzmaStateDecode.c + - LzmaStateTest.c +- ANSI-C LZMA Decoder now can decompress files larger than 4 GB + + +4.17 2005-04-18 +------------------------- +- New example for RAM->RAM compressing/decompressing: + LZMA + BCJ (filter for x86 code): + - LzmaRam.h + - LzmaRam.cpp + - LzmaRamDecode.h + - LzmaRamDecode.c + - -f86 switch for lzma.exe + + +4.16 2005-03-29 +------------------------- +- The bug was fixed in LzmaDecode.c (ANSI-C LZMA Decoder): + If _LZMA_OUT_READ was defined, and if encoded stream was corrupted, + decoder could access memory outside of allocated range. +- Speed optimization of ANSI-C LZMA Decoder (now it's about 20% faster). + Old version of LZMA Decoder now is in file LzmaDecodeSize.c. + LzmaDecodeSize.c can provide slightly smaller code than LzmaDecode.c +- Small speed optimization in LZMA C++ code +- filter for SPARC's code was added +- Simplified version of .7z ANSI-C Decoder was included + + +4.06 2004-09-05 +------------------------- +- The bug in v4.05 was fixed: + LZMA-Encoder didn't release output stream in some cases. + + +4.05 2004-08-25 +------------------------- +- Source code of filters for x86, IA-64, ARM, ARM-Thumb + and PowerPC code was included to SDK +- Some internal minor changes + + +4.04 2004-07-28 +------------------------- +- More compatibility with some C++ compilers + + +4.03 2004-06-18 +------------------------- +- "Benchmark" command was added. It measures compressing + and decompressing speed and shows rating values. + Also it checks hardware errors. + + +4.02 2004-06-10 +------------------------- +- C++ LZMA Encoder/Decoder code now is more portable + and it can be compiled by GCC on Linux. + + +4.01 2004-02-15 +------------------------- +- Some detection of data corruption was enabled. + LzmaDecode.c / RangeDecoderReadByte + ..... + { + rd->ExtraBytes = 1; + return 0xFF; + } + + +4.00 2004-02-13 +------------------------- +- Original version of LZMA SDK + + + +HISTORY of the LZMA +------------------- + 2001-2008: Improvements to LZMA compressing/decompressing code, + keeping compatibility with original LZMA format + 1996-2001: Development of LZMA compression format + + Some milestones: + + 2001-08-30: LZMA compression was added to 7-Zip + 1999-01-02: First version of 7-Zip was released + + +End of document diff --git a/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Library/LzmaCustomDecompressLib/Sdk/DOC/lzma-sdk.txt b/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Library/LzmaCustomDecompressLib/Sdk/DOC/lzma-sdk.txt new file mode 100644 index 00000000..28e05a7d --- /dev/null +++ b/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Library/LzmaCustomDecompressLib/Sdk/DOC/lzma-sdk.txt @@ -0,0 +1,357 @@ +LZMA SDK 19.00 +-------------- + +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 |