| 1 | 7z ANSI-C Decoder 9.35\r |
| 2 | ----------------------\r |
| 3 | \r |
| 4 | 7z ANSI-C provides 7z/LZMA decoding.\r |
| 5 | 7z ANSI-C version is simplified version ported from C++ code.\r |
| 6 | \r |
| 7 | LZMA is default and general compression method of 7z format\r |
| 8 | in 7-Zip compression program (www.7-zip.org). LZMA provides high \r |
| 9 | compression ratio and very fast decompression.\r |
| 10 | \r |
| 11 | \r |
| 12 | LICENSE\r |
| 13 | -------\r |
| 14 | \r |
| 15 | 7z ANSI-C Decoder is part of the LZMA SDK.\r |
| 16 | LZMA SDK is written and placed in the public domain by Igor Pavlov.\r |
| 17 | \r |
| 18 | Files\r |
| 19 | ---------------------\r |
| 20 | \r |
| 21 | 7zDecode.* - Low level 7z decoding\r |
| 22 | 7zExtract.* - High level 7z decoding\r |
| 23 | 7zHeader.* - .7z format constants\r |
| 24 | 7zIn.* - .7z archive opening\r |
| 25 | 7zItem.* - .7z structures\r |
| 26 | 7zMain.c - Test application\r |
| 27 | \r |
| 28 | \r |
| 29 | How To Use\r |
| 30 | ----------\r |
| 31 | \r |
| 32 | You can create .7z archive with 7z.exe, 7za.exe or 7zr.exe:\r |
| 33 | \r |
| 34 | 7z.exe a archive.7z *.htm -r -mx -m0fb=255\r |
| 35 | \r |
| 36 | If you have big number of files in archive, and you need fast extracting, \r |
| 37 | you can use partly-solid archives:\r |
| 38 | \r |
| 39 | 7za.exe a archive.7z *.htm -ms=512K -r -mx -m0fb=255 -m0d=512K\r |
| 40 | \r |
| 41 | In that example 7-Zip will use 512KB solid blocks. So it needs to decompress only \r |
| 42 | 512KB for extracting one file from such archive.\r |
| 43 | \r |
| 44 | \r |
| 45 | Limitations of current version of 7z ANSI-C Decoder\r |
| 46 | ---------------------------------------------------\r |
| 47 | \r |
| 48 | - It reads only "FileName", "Size", "LastWriteTime" and "CRC" information for each file in archive.\r |
| 49 | - It supports only LZMA and Copy (no compression) methods with BCJ or BCJ2 filters.\r |
| 50 | - It converts original UTF-16 Unicode file names to UTF-8 Unicode file names.\r |
| 51 | \r |
| 52 | These limitations will be fixed in future versions.\r |
| 53 | \r |
| 54 | \r |
| 55 | Using 7z ANSI-C Decoder Test application:\r |
| 56 | -----------------------------------------\r |
| 57 | \r |
| 58 | Usage: 7zDec <command> <archive_name>\r |
| 59 | \r |
| 60 | <Command>:\r |
| 61 | e: Extract files from archive\r |
| 62 | l: List contents of archive\r |
| 63 | t: Test integrity of archive\r |
| 64 | \r |
| 65 | Example: \r |
| 66 | \r |
| 67 | 7zDec l archive.7z\r |
| 68 | \r |
| 69 | lists contents of archive.7z\r |
| 70 | \r |
| 71 | 7zDec e archive.7z\r |
| 72 | \r |
| 73 | extracts files from archive.7z to current folder.\r |
| 74 | \r |
| 75 | \r |
| 76 | How to use .7z Decoder\r |
| 77 | ----------------------\r |
| 78 | \r |
| 79 | Memory allocation\r |
| 80 | ~~~~~~~~~~~~~~~~~\r |
| 81 | \r |
| 82 | 7z Decoder uses two memory pools:\r |
| 83 | 1) Temporary pool\r |
| 84 | 2) Main pool\r |
| 85 | Such scheme can allow you to avoid fragmentation of allocated blocks.\r |
| 86 | \r |
| 87 | \r |
| 88 | Steps for using 7z decoder\r |
| 89 | --------------------------\r |
| 90 | \r |
| 91 | Use code at 7zMain.c as example.\r |
| 92 | \r |
| 93 | 1) Declare variables:\r |
| 94 | inStream /* implements ILookInStream interface */\r |
| 95 | CSzArEx db; /* 7z archive database structure */\r |
| 96 | ISzAlloc allocImp; /* memory functions for main pool */\r |
| 97 | ISzAlloc allocTempImp; /* memory functions for temporary pool */\r |
| 98 | \r |
| 99 | 2) call CrcGenerateTable(); function to initialize CRC structures.\r |
| 100 | \r |
| 101 | 3) call SzArEx_Init(&db); function to initialize db structures.\r |
| 102 | \r |
| 103 | 4) call SzArEx_Open(&db, inStream, &allocMain, &allocTemp) to open archive\r |
| 104 | \r |
| 105 | This function opens archive "inStream" and reads headers to "db".\r |
| 106 | All items in "db" will be allocated with "allocMain" functions.\r |
| 107 | SzArEx_Open function allocates and frees temporary structures by "allocTemp" functions.\r |
| 108 | \r |
| 109 | 5) List items or Extract items\r |
| 110 | \r |
| 111 | Listing code:\r |
| 112 | ~~~~~~~~~~~~~\r |
| 113 | \r |
| 114 | Use SzArEx_GetFileNameUtf16 function. Look example code in C\Util\7z\7zMain.c file. \r |
| 115 | \r |
| 116 | \r |
| 117 | Extracting code:\r |
| 118 | ~~~~~~~~~~~~~~~~\r |
| 119 | \r |
| 120 | SZ_RESULT SzAr_Extract(\r |
| 121 | CArchiveDatabaseEx *db,\r |
| 122 | ILookInStream *inStream, \r |
| 123 | UInt32 fileIndex, /* index of file */\r |
| 124 | UInt32 *blockIndex, /* index of solid block */\r |
| 125 | Byte **outBuffer, /* pointer to pointer to output buffer (allocated with allocMain) */\r |
| 126 | size_t *outBufferSize, /* buffer size for output buffer */\r |
| 127 | size_t *offset, /* offset of stream for required file in *outBuffer */\r |
| 128 | size_t *outSizeProcessed, /* size of file in *outBuffer */\r |
| 129 | ISzAlloc *allocMain,\r |
| 130 | ISzAlloc *allocTemp);\r |
| 131 | \r |
| 132 | If you need to decompress more than one file, you can send these values from previous call:\r |
| 133 | blockIndex, \r |
| 134 | outBuffer, \r |
| 135 | outBufferSize,\r |
| 136 | You can consider "outBuffer" as cache of solid block. If your archive is solid, \r |
| 137 | it will increase decompression speed.\r |
| 138 | \r |
| 139 | After decompressing you must free "outBuffer":\r |
| 140 | allocImp.Free(outBuffer);\r |
| 141 | \r |
| 142 | 6) call SzArEx_Free(&db, allocImp.Free) to free allocated items in "db".\r |
| 143 | \r |
| 144 | \r |
| 145 | \r |
| 146 | \r |
| 147 | Memory requirements for .7z decoding \r |
| 148 | ------------------------------------\r |
| 149 | \r |
| 150 | Memory usage for Archive opening:\r |
| 151 | - Temporary pool:\r |
| 152 | - Memory for uncompressed .7z headers\r |
| 153 | - some other temporary blocks\r |
| 154 | - Main pool:\r |
| 155 | - Memory for database: \r |
| 156 | Estimated size of one file structures in solid archive:\r |
| 157 | - Size (4 or 8 Bytes)\r |
| 158 | - CRC32 (4 bytes)\r |
| 159 | - LastWriteTime (8 bytes)\r |
| 160 | - Some file information (4 bytes)\r |
| 161 | - File Name (variable length) + pointer + allocation structures\r |
| 162 | \r |
| 163 | Memory usage for archive Decompressing:\r |
| 164 | - Temporary pool:\r |
| 165 | - Memory for LZMA decompressing structures\r |
| 166 | - Main pool:\r |
| 167 | - Memory for decompressed solid block\r |
| 168 | - Memory for temprorary buffers, if BCJ2 fileter is used. Usually these \r |
| 169 | temprorary buffers can be about 15% of solid block size. \r |
| 170 | \r |
| 171 | \r |
| 172 | 7z Decoder doesn't allocate memory for compressed blocks. \r |
| 173 | Instead of this, you must allocate buffer with desired \r |
| 174 | size before calling 7z Decoder. Use 7zMain.c as example.\r |
| 175 | \r |
| 176 | \r |
| 177 | Defines\r |
| 178 | -------\r |
| 179 | \r |
| 180 | _SZ_ALLOC_DEBUG - define it if you want to debug alloc/free operations to stderr.\r |
| 181 | \r |
| 182 | \r |
| 183 | ---\r |
| 184 | \r |
| 185 | http://www.7-zip.org\r |
| 186 | http://www.7-zip.org/sdk.html\r |
| 187 | http://www.7-zip.org/support.html\r |