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Diffstat (limited to 'src/liblzma/api/lzma/lzma.h')
| -rw-r--r-- | src/liblzma/api/lzma/lzma.h | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/src/liblzma/api/lzma/lzma.h b/src/liblzma/api/lzma/lzma.h new file mode 100644 index 00000000..0fe74854 --- /dev/null +++ b/src/liblzma/api/lzma/lzma.h @@ -0,0 +1,312 @@ +/** + * \file lzma/lzma.h + * \brief LZMA filter + * + * \author Copyright (C) 1999-2006 Igor Pavlov + * \author Copyright (C) 2007 Lasse Collin + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + */ + +#ifndef LZMA_H_INTERNAL +# error Never include this file directly. Use <lzma.h> instead. +#endif + + +/** + * \brief Filter ID + * + * Filter ID of the LZMA filter. This is used as lzma_options_filter.id. + */ +#define LZMA_FILTER_LZMA LZMA_VLI_C(0x40) + + +/** + * \brief LZMA compression modes + * + * Currently there are only two modes. Earlier LZMA SDKs had also third + * mode between fast and best. + */ +typedef enum { + LZMA_MODE_INVALID = -1, + /**< + * \brief Invalid mode + * + * Used as array terminator in lzma_available_modes. + */ + + + LZMA_MODE_FAST = 0, + /**< + * \brief Fast compression + * + * Fast mode is usually at its best when combined with + * a hash chain match finder. + */ + + LZMA_MODE_BEST = 2 + /**< + * \brief Best compression ratio + * + * This is usually notably slower than fast mode. Use this + * together with binary tree match finders to expose the + * full potential of the LZMA encoder. + */ +} lzma_mode; + + +/** + * \brief Match finders + * + * Match finder has major effect on both speed and compression ratio. + * Usually hash chains are faster than binary trees. + */ +typedef enum { + LZMA_MF_INVALID = -1, + /**< + * \brief Invalid match finder ID + * + * Used as array terminator in lzma_available_match_finders. + */ + + LZMA_MF_HC3 = 0x03, + /**< + * \brief Hash Chain with 3 bytes hashing + * + * \todo Memory requirements + * + * \note It's possible that this match finder gets + * removed in future. The definition will stay + * in this header, but liblzma may return + * LZMA_HEADER_ERROR if it is specified (just + * like it would if the match finder had been + * disabled at compile time). + */ + + LZMA_MF_HC4 = 0x04, + /**< + * \brief Hash Chain with 4 bytes hashing + * + * Memory requirements: 7.5 * dictionary_size + 4 MiB + * + * \note It's possible that this match finder gets + * removed in future. The definition will stay + * in this header, but liblzma may return + * LZMA_HEADER_ERROR if it is specified (just + * like it would if the match finder had been + * disabled at compile time). + */ + + LZMA_MF_BT2 = 0x12, + /**< + * \brief Binary Tree with 2 bytes hashing + * + * Memory requirements: 9.5 * dictionary_size + 4 MiB + */ + + LZMA_MF_BT3 = 0x13, + /**< + * \brief Binary Tree with 3 bytes hashing + * + * Memory requirements: 11.5 * dictionary_size + 4 MiB + */ + + LZMA_MF_BT4 = 0x14 + /**< + * \brief Binary Tree with 4 bytes hashing + * + * Memory requirements: 11.5 * dictionary_size + 4 MiB + */ +} lzma_match_finder; + + +/** + * \brief Options specific to the LZMA method handler + */ +typedef struct { + /********************************** + * LZMA encoding/decoding options * + **********************************/ + + /* These options are required in encoder and also with raw decoding. */ + + /** + * \brief Dictionary size in bytes + * + * Dictionary size indicates how many bytes of the recently processed + * uncompressed data is kept in memory. One method to reduce size of + * the uncompressed data is to store distance-length pairs, which + * indicate what data to repeat from the dictionary buffer. Thus, + * the bigger the dictionary, the better compression ratio usually is. + * + * Raw decoding: Too big dictionary does no other harm than + * wasting memory. This value is ignored by lzma_raw_decode_buffer(), + * because it uses the target buffer as the dictionary. + */ + uint32_t dictionary_size; +# define LZMA_DICTIONARY_SIZE_MIN 1 +# define LZMA_DICTIONARY_SIZE_MAX (UINT32_C(1) << 30) +# define LZMA_DICTIONARY_SIZE_DEFAULT (UINT32_C(1) << 23) + + /** + * \brief Number of literal context bits + * + * How many of the highest bits of the previous uncompressed + * eight-bit byte (also known as `literal') are taken into + * account when predicting the bits of the next literal. + * + * \todo Example + */ + uint32_t literal_context_bits; +# define LZMA_LITERAL_CONTEXT_BITS_MIN 0 +# define LZMA_LITERAL_CONTEXT_BITS_MAX 8 +# define LZMA_LITERAL_CONTEXT_BITS_DEFAULT 3 + + /** + * \brief Number of literal position bits + * + * How many of the lowest bits of the current position (number + * of bytes from the beginning of the uncompressed data) in the + * uncompressed data is taken into account when predicting the + * bits of the next literal (a single eight-bit byte). + * + * \todo Example + */ + uint32_t literal_pos_bits; +# define LZMA_LITERAL_POS_BITS_MIN 0 +# define LZMA_LITERAL_POS_BITS_MAX 4 +# define LZMA_LITERAL_POS_BITS_DEFAULT 0 + + /** + * \brief Number of position bits + * + * How many of the lowest bits of the current position in the + * uncompressed data is taken into account when estimating + * probabilities of matches. A match is a sequence of bytes for + * which a matching sequence is found from the dictionary and + * thus can be stored as distance-length pair. + * + * Example: If most of the matches occur at byte positions + * of 8 * n + 3, that is, 3, 11, 19, ... set pos_bits to 3, + * because 2**3 == 8. + */ + uint32_t pos_bits; +# define LZMA_POS_BITS_MIN 0 +# define LZMA_POS_BITS_MAX 4 +# define LZMA_POS_BITS_DEFAULT 2 + + /** + * \brief Pointer to an initial dictionary + * + * It is possible to initialize the LZ77 history window using + * a preset dictionary. Here is a good quote from zlib's + * documentation; this applies to LZMA as is: + * + * "The dictionary should consist of strings (byte sequences) that + * are likely to be encountered later in the data to be compressed, + * with the most commonly used strings preferably put towards the + * end of the dictionary. Using a dictionary is most useful when + * the data to be compressed is short and can be predicted with + * good accuracy; the data can then be compressed better than + * with the default empty dictionary." + * (From deflateSetDictionary() in zlib.h of zlib version 1.2.3) + * + * This feature should be used only in special situations. + * It works correctly only with raw encoding and decoding. + * Currently none of the container formats supported by + * liblzma allow preset dictionary when decoding, thus if + * you create a .lzma file with preset dictionary, it cannot + * be decoded with the regular .lzma decoder functions. + * + * \todo This feature is not implemented yet. + */ + const uint8_t *preset_dictionary; + + /** + * \brief Size of the preset dictionary + * + * Specifies the size of the preset dictionary. If the size is + * bigger than dictionary_size, only the last dictionary_size + * bytes are processed. + * + * This variable is read only when preset_dictionary is not NULL. + */ + uint32_t preset_dictionary_size; + + /****************************************** + * LZMA options needed only when encoding * + ******************************************/ + + /** LZMA compression mode */ + lzma_mode mode; + + /** + * \brief Number of fast bytes + * + * Number of fast bytes determines how many bytes the encoder + * compares from the match candidates when looking for the best + * match. Bigger fast bytes value usually increase both compression + * ratio and time. + */ + uint32_t fast_bytes; +# define LZMA_FAST_BYTES_MIN 5 +# define LZMA_FAST_BYTES_MAX 273 +# define LZMA_FAST_BYTES_DEFAULT 128 + + /** Match finder ID */ + lzma_match_finder match_finder; + + /** + * \brief Match finder cycles + * + * Higher values give slightly better compression ratio but + * decrease speed. Use special value 0 to let liblzma use + * match-finder-dependent default value. + * + * \todo Write much better description. + */ + uint32_t match_finder_cycles; + +} lzma_options_lzma; + + +/** + * \brief Available LZMA encoding modes + * + * Pointer to an array containing the list of available encoding modes. + * + * This variable is available only if LZMA encoder has been enabled. + */ +extern const lzma_mode *const lzma_available_modes; + + +/** + * \brief Available match finders + * + * Pointer to an array containing the list of available match finders. + * The last element is LZMA_MF_INVALID. + * + * This variable is available only if LZMA encoder has been enabled. + */ +extern const lzma_match_finder *const lzma_available_match_finders; + + +/** + * \brief Table of presets for the LZMA filter + * + * lzma_presets[0] is the fastest and lzma_preset_lzma[8] is the slowest. + * These presets match the switches -1 .. -9 of the lzma command line tool + * + * The preset values are subject to changes between liblzma versions. + * + * This variable is available only if LZMA encoder has been enabled. + */ +extern const lzma_options_lzma lzma_preset_lzma[9]; |