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| author | Mounir IDRASSI <mounir.idrassi@idrix.fr> | 2022-02-09 23:47:25 +0100 |
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| committer | Mounir IDRASSI <mounir.idrassi@idrix.fr> | 2022-02-10 01:21:17 +0100 |
| commit | 1ef05f24e28938c7a0608b4c6b369094d1dccaa6 (patch) | |
| tree | 680a5b679c78cd999045abf207bfc7363aa1d9b9 /src/Common/lzma/lzma-sdk.txt | |
| parent | 302dc37fb9baa45c5864af533664c4139e209590 (diff) | |
| download | VeraCrypt-1ef05f24e28938c7a0608b4c6b369094d1dccaa6.tar.gz VeraCrypt-1ef05f24e28938c7a0608b4c6b369094d1dccaa6.zip | |
Windows: Reduce the size of installers by almost 50% by using LZMA compression instead of DEFLATE
Diffstat (limited to 'src/Common/lzma/lzma-sdk.txt')
| -rw-r--r-- | src/Common/lzma/lzma-sdk.txt | 404 |
1 files changed, 404 insertions, 0 deletions
diff --git a/src/Common/lzma/lzma-sdk.txt b/src/Common/lzma/lzma-sdk.txt new file mode 100644 index 00000000..9621c8d5 --- /dev/null +++ b/src/Common/lzma/lzma-sdk.txt @@ -0,0 +1,404 @@ +LZMA SDK 21.07 +-------------- + +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 +------------------ +There are several otpions to compile 7-Zip with different compilers: gcc and clang. +Also 7-Zip code contains two versions for some critical parts of code: in C and in Assembeler. +So if you compile the version with Assembeler code, you will get faster 7-Zip binary. + +7-Zip's assembler code uses the following syntax for different platforms: + +1) x86 and x86-64 (AMD64): MASM syntax. + There are 2 programs that supports MASM syntax in Linux. +' 'Asmc Macro Assembler and JWasm. But JWasm now doesn't support some + cpu instructions used in 7-Zip. + So you must install Asmc Macro Assembler in Linux, if you want to compile fastest version + of 7-Zip x86 and x86-64: + https://github.com/nidud/asmc + +2) arm64: GNU assembler for ARM64 with preprocessor. + That systax of that arm64 assembler code in 7-Zip is supported by GCC and CLANG for ARM64. + +There are different binaries that can be compiled from 7-Zip source. +There are 2 main files in folder for compiling: + makefile - that can be used for compiling Windows version of 7-Zip with nmake command + makefile.gcc - that can be used for compiling Linux/macOS versions of 7-Zip with make command + +At first you must change the current folder to folder that contains `makefile.gcc`: + + cd CPP/7zip/Bundles/Alone7z + +Then you can compile `makefile.gcc` with the command: + + make -j -f makefile.gcc + +Also there are additional "*.mak" files in folder "CPP/7zip/" that can be used to compile +7-Zip binaries with optimized code and optimzing options. + +To compile with GCC without assembler: + cd CPP/7zip/Bundles/Alone7z + make -j -f ../../cmpl_gcc.mak + +To compile with CLANG without assembler: + make -j -f ../../cmpl_clang.mak + +To compile 7-Zip for x86-64 with asmc assembler: + make -j -f ../../cmpl_gcc_x64.mak + +To compile 7-Zip for arm64 with assembler: + make -j -f ../../cmpl_gcc_arm64.mak + +To compile 7-Zip for arm64 for macOS: + make -j -f ../../cmpl_mac_arm64.mak + +Also you can change some compiler options in the mak files: + cmpl_gcc.mak + var_gcc.mak + warn_gcc.mak + + + +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 |