1LZMA SDK 23.01 2-------------- 3 4LZMA SDK provides the documentation, samples, header files, 5libraries, and tools you need to develop applications that 6use 7z / LZMA / LZMA2 / XZ compression. 7 8LZMA is an improved version of famous LZ77 compression algorithm. 9It was improved in way of maximum increasing of compression ratio, 10keeping high decompression speed and low memory requirements for 11decompressing. 12 13LZMA2 is a LZMA based compression method. LZMA2 provides better 14multithreading support for compression than LZMA and some other improvements. 15 167z is a file format for data compression and file archiving. 177z is a main file format for 7-Zip compression program (www.7-zip.org). 187z format supports different compression methods: LZMA, LZMA2 and others. 197z also supports AES-256 based encryption. 20 21XZ is a file format for data compression that uses LZMA2 compression. 22XZ format provides additional features: SHA/CRC check, filters for 23improved compression ratio, splitting to blocks and streams, 24 25 26 27LICENSE 28------- 29 30LZMA SDK is written and placed in the public domain by Igor Pavlov. 31 32Some code in LZMA SDK is based on public domain code from another developers: 33 1) PPMd var.H (2001): Dmitry Shkarin 34 2) SHA-256: Wei Dai (Crypto++ library) 35 36Anyone is free to copy, modify, publish, use, compile, sell, or distribute the 37original LZMA SDK code, either in source code form or as a compiled binary, for 38any purpose, commercial or non-commercial, and by any means. 39 40LZMA SDK code is compatible with open source licenses, for example, you can 41include it to GNU GPL or GNU LGPL code. 42 43 44LZMA SDK Contents 45----------------- 46 47 Source code: 48 49 - C / C++ / C# / Java - LZMA compression and decompression 50 - C / C++ - LZMA2 compression and decompression 51 - C / C++ - XZ compression and decompression 52 - C - 7z decompression 53 - C++ - 7z compression and decompression 54 - C - small SFXs for installers (7z decompression) 55 - C++ - SFXs and SFXs for installers (7z decompression) 56 57 Precomiled binaries: 58 59 - console programs for lzma / 7z / xz compression and decompression 60 - SFX modules for installers. 61 62 63UNIX/Linux version 64------------------ 65There are several otpions to compile 7-Zip with different compilers: gcc and clang. 66Also 7-Zip code contains two versions for some critical parts of code: in C and in Assembeler. 67So if you compile the version with Assembeler code, you will get faster 7-Zip binary. 68 697-Zip's assembler code uses the following syntax for different platforms: 70 711) x86 and x86-64 (AMD64): MASM syntax. 72 There are 2 programs that supports MASM syntax in Linux. 73' 'Asmc Macro Assembler and JWasm. But JWasm now doesn't support some 74 cpu instructions used in 7-Zip. 75 So you must install Asmc Macro Assembler in Linux, if you want to compile fastest version 76 of 7-Zip x86 and x86-64: 77 https://github.com/nidud/asmc 78 792) arm64: GNU assembler for ARM64 with preprocessor. 80 That systax of that arm64 assembler code in 7-Zip is supported by GCC and CLANG for ARM64. 81 82There are different binaries that can be compiled from 7-Zip source. 83There are 2 main files in folder for compiling: 84 makefile - that can be used for compiling Windows version of 7-Zip with nmake command 85 makefile.gcc - that can be used for compiling Linux/macOS versions of 7-Zip with make command 86 87At first you must change the current folder to folder that contains `makefile.gcc`: 88 89 cd CPP/7zip/Bundles/Alone7z 90 91Then you can compile `makefile.gcc` with the command: 92 93 make -j -f makefile.gcc 94 95Also there are additional "*.mak" files in folder "CPP/7zip/" that can be used to compile 967-Zip binaries with optimized code and optimzing options. 97 98To compile with GCC without assembler: 99 cd CPP/7zip/Bundles/Alone7z 100 make -j -f ../../cmpl_gcc.mak 101 102To compile with CLANG without assembler: 103 make -j -f ../../cmpl_clang.mak 104 105To compile 7-Zip for x86-64 with asmc assembler: 106 make -j -f ../../cmpl_gcc_x64.mak 107 108To compile 7-Zip for arm64 with assembler: 109 make -j -f ../../cmpl_gcc_arm64.mak 110 111To compile 7-Zip for arm64 for macOS: 112 make -j -f ../../cmpl_mac_arm64.mak 113 114Also you can change some compiler options in the mak files: 115 cmpl_gcc.mak 116 var_gcc.mak 117 warn_gcc.mak 118 119 120 121Also you can use p7zip (port of 7-Zip for POSIX systems like Unix or Linux): 122 123 http://p7zip.sourceforge.net/ 124 125 126Files 127----- 128 129DOC/7zC.txt - 7z ANSI-C Decoder description 130DOC/7zFormat.txt - 7z Format description 131DOC/installer.txt - information about 7-Zip for installers 132DOC/lzma.txt - LZMA compression description 133DOC/lzma-sdk.txt - LZMA SDK description (this file) 134DOC/lzma-history.txt - history of LZMA SDK 135DOC/lzma-specification.txt - Specification of LZMA 136DOC/Methods.txt - Compression method IDs for .7z 137 138bin/installer/ - example script to create installer that uses SFX module, 139 140bin/7zdec.exe - simplified 7z archive decoder 141bin/7zr.exe - 7-Zip console program (reduced version) 142bin/x64/7zr.exe - 7-Zip console program (reduced version) (x64 version) 143bin/lzma.exe - file->file LZMA encoder/decoder for Windows 144bin/7zS2.sfx - small SFX module for installers (GUI version) 145bin/7zS2con.sfx - small SFX module for installers (Console version) 146bin/7zSD.sfx - SFX module for installers. 147 148 1497zDec.exe 150--------- 1517zDec.exe is simplified 7z archive decoder. 152It supports only LZMA, LZMA2, and PPMd methods. 1537zDec decodes whole solid block from 7z archive to RAM. 154The RAM consumption can be high. 155 156 157 158 159Source code structure 160--------------------- 161 162 163Asm/ - asm files (optimized code for CRC calculation and Intel-AES encryption) 164 165C/ - C files (compression / decompression and other) 166 Util/ 167 7z - 7z decoder program (decoding 7z files) 168 Lzma - LZMA program (file->file LZMA encoder/decoder). 169 LzmaLib - LZMA library (.DLL for Windows) 170 SfxSetup - small SFX module for installers 171 172CPP/ -- CPP files 173 174 Common - common files for C++ projects 175 Windows - common files for Windows related code 176 177 7zip - files related to 7-Zip 178 179 Archive - files related to archiving 180 181 Common - common files for archive handling 182 7z - 7z C++ Encoder/Decoder 183 184 Bundles - Modules that are bundles of other modules (files) 185 186 Alone7z - 7zr.exe: Standalone 7-Zip console program (reduced version) 187 Format7zExtractR - 7zxr.dll: Reduced version of 7z DLL: extracting from 7z/LZMA/BCJ/BCJ2. 188 Format7zR - 7zr.dll: Reduced version of 7z DLL: extracting/compressing to 7z/LZMA/BCJ/BCJ2 189 LzmaCon - lzma.exe: LZMA compression/decompression 190 LzmaSpec - example code for LZMA Specification 191 SFXCon - 7zCon.sfx: Console 7z SFX module 192 SFXSetup - 7zS.sfx: 7z SFX module for installers 193 SFXWin - 7z.sfx: GUI 7z SFX module 194 195 Common - common files for 7-Zip 196 197 Compress - files for compression/decompression 198 199 Crypto - files for encryption / decompression 200 201 UI - User Interface files 202 203 Client7z - Test application for 7za.dll, 7zr.dll, 7zxr.dll 204 Common - Common UI files 205 Console - Code for console program (7z.exe) 206 Explorer - Some code from 7-Zip Shell extension 207 FileManager - Some GUI code from 7-Zip File Manager 208 GUI - Some GUI code from 7-Zip 209 210 211CS/ - C# files 212 7zip 213 Common - some common files for 7-Zip 214 Compress - files related to compression/decompression 215 LZ - files related to LZ (Lempel-Ziv) compression algorithm 216 LZMA - LZMA compression/decompression 217 LzmaAlone - file->file LZMA compression/decompression 218 RangeCoder - Range Coder (special code of compression/decompression) 219 220Java/ - Java files 221 SevenZip 222 Compression - files related to compression/decompression 223 LZ - files related to LZ (Lempel-Ziv) compression algorithm 224 LZMA - LZMA compression/decompression 225 RangeCoder - Range Coder (special code of compression/decompression) 226 227 228Note: 229 Asm / C / C++ source code of LZMA SDK is part of 7-Zip's source code. 230 7-Zip's source code can be downloaded from 7-Zip's SourceForge page: 231 232 http://sourceforge.net/projects/sevenzip/ 233 234 235 236LZMA features 237------------- 238 - Variable dictionary size (up to 1 GB) 239 - Estimated compressing speed: about 2 MB/s on 2 GHz CPU 240 - Estimated decompressing speed: 241 - 20-30 MB/s on modern 2 GHz cpu 242 - 1-2 MB/s on 200 MHz simple RISC cpu: (ARM, MIPS, PowerPC) 243 - Small memory requirements for decompressing (16 KB + DictionarySize) 244 - Small code size for decompressing: 5-8 KB 245 246LZMA decoder uses only integer operations and can be 247implemented in any modern 32-bit CPU (or on 16-bit CPU with some conditions). 248 249Some critical operations that affect the speed of LZMA decompression: 250 1) 32*16 bit integer multiply 251 2) Mispredicted branches (penalty mostly depends from pipeline length) 252 3) 32-bit shift and arithmetic operations 253 254The speed of LZMA decompressing mostly depends from CPU speed. 255Memory speed has no big meaning. But if your CPU has small data cache, 256overall weight of memory speed will slightly increase. 257 258 259How To Use 260---------- 261 262Using LZMA encoder/decoder executable 263-------------------------------------- 264 265Usage: LZMA <e|d> inputFile outputFile [<switches>...] 266 267 e: encode file 268 269 d: decode file 270 271 b: Benchmark. There are two tests: compressing and decompressing 272 with LZMA method. Benchmark shows rating in MIPS (million 273 instructions per second). Rating value is calculated from 274 measured speed and it is normalized with Intel's Core 2 results. 275 Also Benchmark checks possible hardware errors (RAM 276 errors in most cases). Benchmark uses these settings: 277 (-a1, -d21, -fb32, -mfbt4). You can change only -d parameter. 278 Also you can change the number of iterations. Example for 30 iterations: 279 LZMA b 30 280 Default number of iterations is 10. 281 282<Switches> 283 284 285 -a{N}: set compression mode 0 = fast, 1 = normal 286 default: 1 (normal) 287 288 d{N}: Sets Dictionary size - [0, 30], default: 23 (8MB) 289 The maximum value for dictionary size is 1 GB = 2^30 bytes. 290 Dictionary size is calculated as DictionarySize = 2^N bytes. 291 For decompressing file compressed by LZMA method with dictionary 292 size D = 2^N you need about D bytes of memory (RAM). 293 294 -fb{N}: set number of fast bytes - [5, 273], default: 128 295 Usually big number gives a little bit better compression ratio 296 and slower compression process. 297 298 -lc{N}: set number of literal context bits - [0, 8], default: 3 299 Sometimes lc=4 gives gain for big files. 300 301 -lp{N}: set number of literal pos bits - [0, 4], default: 0 302 lp switch is intended for periodical data when period is 303 equal 2^N. For example, for 32-bit (4 bytes) 304 periodical data you can use lp=2. Often it's better to set lc0, 305 if you change lp switch. 306 307 -pb{N}: set number of pos bits - [0, 4], default: 2 308 pb switch is intended for periodical data 309 when period is equal 2^N. 310 311 -mf{MF_ID}: set Match Finder. Default: bt4. 312 Algorithms from hc* group doesn't provide good compression 313 ratio, but they often works pretty fast in combination with 314 fast mode (-a0). 315 316 Memory requirements depend from dictionary size 317 (parameter "d" in table below). 318 319 MF_ID Memory Description 320 321 bt2 d * 9.5 + 4MB Binary Tree with 2 bytes hashing. 322 bt3 d * 11.5 + 4MB Binary Tree with 3 bytes hashing. 323 bt4 d * 11.5 + 4MB Binary Tree with 4 bytes hashing. 324 hc4 d * 7.5 + 4MB Hash Chain with 4 bytes hashing. 325 326 -eos: write End Of Stream marker. By default LZMA doesn't write 327 eos marker, since LZMA decoder knows uncompressed size 328 stored in .lzma file header. 329 330 -si: Read data from stdin (it will write End Of Stream marker). 331 -so: Write data to stdout 332 333 334Examples: 335 3361) LZMA e file.bin file.lzma -d16 -lc0 337 338compresses file.bin to file.lzma with 64 KB dictionary (2^16=64K) 339and 0 literal context bits. -lc0 allows to reduce memory requirements 340for decompression. 341 342 3432) LZMA e file.bin file.lzma -lc0 -lp2 344 345compresses file.bin to file.lzma with settings suitable 346for 32-bit periodical data (for example, ARM or MIPS code). 347 3483) LZMA d file.lzma file.bin 349 350decompresses file.lzma to file.bin. 351 352 353Compression ratio hints 354----------------------- 355 356Recommendations 357--------------- 358 359To increase the compression ratio for LZMA compressing it's desirable 360to have aligned data (if it's possible) and also it's desirable to locate 361data in such order, where code is grouped in one place and data is 362grouped in other place (it's better than such mixing: code, data, code, 363data, ...). 364 365 366Filters 367------- 368You can increase the compression ratio for some data types, using 369special filters before compressing. For example, it's possible to 370increase the compression ratio on 5-10% for code for those CPU ISAs: 371x86, IA-64, ARM, ARM-Thumb, PowerPC, SPARC. 372 373You can find C source code of such filters in C/Bra*.* files 374 375You can check the compression ratio gain of these filters with such 3767-Zip commands (example for ARM code): 377No filter: 378 7z a a1.7z a.bin -m0=lzma 379 380With filter for little-endian ARM code: 381 7z a a2.7z a.bin -m0=arm -m1=lzma 382 383It works in such manner: 384Compressing = Filter_encoding + LZMA_encoding 385Decompressing = LZMA_decoding + Filter_decoding 386 387Compressing and decompressing speed of such filters is very high, 388so it will not increase decompressing time too much. 389Moreover, it reduces decompression time for LZMA_decoding, 390since compression ratio with filtering is higher. 391 392These filters convert CALL (calling procedure) instructions 393from relative offsets to absolute addresses, so such data becomes more 394compressible. 395 396For some ISAs (for example, for MIPS) it's impossible to get gain from such filter. 397 398 399 400--- 401 402http://www.7-zip.org 403http://www.7-zip.org/sdk.html 404http://www.7-zip.org/support.html 405