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author | mm <mm@FreeBSD.org> | 2010-05-10 06:59:50 +0000 |
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committer | mm <mm@FreeBSD.org> | 2010-05-10 06:59:50 +0000 |
commit | 5c358d45429b654efa9c8177ecd370a7965ec1a7 (patch) | |
tree | d2d916954c6a66a3168ee356b5f24da01c2017d6 /contrib/xz/src/liblzma/lzma/lzma_common.h | |
parent | 3e09decd1986826f54af1a47be97bb87c1220783 (diff) | |
parent | 1008b7c6744a190c5b15aaf8cab1054671e4c7c3 (diff) | |
download | FreeBSD-src-5c358d45429b654efa9c8177ecd370a7965ec1a7.zip FreeBSD-src-5c358d45429b654efa9c8177ecd370a7965ec1a7.tar.gz |
Import of liblzma, xz, xzdec, lzmainfo from vendor branch
Add support for xz and lzma to lesspipe.sh (xzless, lzless)
Bump __FreeBSD_version
Approved by: delphij (mentor)
MFC after: 2 weeks
Diffstat (limited to 'contrib/xz/src/liblzma/lzma/lzma_common.h')
-rw-r--r-- | contrib/xz/src/liblzma/lzma/lzma_common.h | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/contrib/xz/src/liblzma/lzma/lzma_common.h b/contrib/xz/src/liblzma/lzma/lzma_common.h new file mode 100644 index 0000000..e31e285 --- /dev/null +++ b/contrib/xz/src/liblzma/lzma/lzma_common.h @@ -0,0 +1,223 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file lzma_common.h +/// \brief Private definitions common to LZMA encoder and decoder +/// +// Authors: Igor Pavlov +// Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#ifndef LZMA_LZMA_COMMON_H +#define LZMA_LZMA_COMMON_H + +#include "common.h" +#include "range_common.h" + + +/////////////////// +// Miscellaneous // +/////////////////// + +/// Maximum number of position states. A position state is the lowest pos bits +/// number of bits of the current uncompressed offset. In some places there +/// are different sets of probabilities for different pos states. +#define POS_STATES_MAX (1 << LZMA_PB_MAX) + + +/// Validates lc, lp, and pb. +static inline bool +is_lclppb_valid(const lzma_options_lzma *options) +{ + return options->lc <= LZMA_LCLP_MAX && options->lp <= LZMA_LCLP_MAX + && options->lc + options->lp <= LZMA_LCLP_MAX + && options->pb <= LZMA_PB_MAX; +} + + +/////////// +// State // +/////////// + +/// This enum is used to track which events have occurred most recently and +/// in which order. This information is used to predict the next event. +/// +/// Events: +/// - Literal: One 8-bit byte +/// - Match: Repeat a chunk of data at some distance +/// - Long repeat: Multi-byte match at a recently seen distance +/// - Short repeat: One-byte repeat at a recently seen distance +/// +/// The event names are in from STATE_oldest_older_previous. REP means +/// either short or long repeated match, and NONLIT means any non-literal. +typedef enum { + STATE_LIT_LIT, + STATE_MATCH_LIT_LIT, + STATE_REP_LIT_LIT, + STATE_SHORTREP_LIT_LIT, + STATE_MATCH_LIT, + STATE_REP_LIT, + STATE_SHORTREP_LIT, + STATE_LIT_MATCH, + STATE_LIT_LONGREP, + STATE_LIT_SHORTREP, + STATE_NONLIT_MATCH, + STATE_NONLIT_REP, +} lzma_lzma_state; + + +/// Total number of states +#define STATES 12 + +/// The lowest 7 states indicate that the previous state was a literal. +#define LIT_STATES 7 + + +/// Indicate that the latest state was a literal. +#define update_literal(state) \ + state = ((state) <= STATE_SHORTREP_LIT_LIT \ + ? STATE_LIT_LIT \ + : ((state) <= STATE_LIT_SHORTREP \ + ? (state) - 3 \ + : (state) - 6)) + +/// Indicate that the latest state was a match. +#define update_match(state) \ + state = ((state) < LIT_STATES ? STATE_LIT_MATCH : STATE_NONLIT_MATCH) + +/// Indicate that the latest state was a long repeated match. +#define update_long_rep(state) \ + state = ((state) < LIT_STATES ? STATE_LIT_LONGREP : STATE_NONLIT_REP) + +/// Indicate that the latest state was a short match. +#define update_short_rep(state) \ + state = ((state) < LIT_STATES ? STATE_LIT_SHORTREP : STATE_NONLIT_REP) + +/// Test if the previous state was a literal. +#define is_literal_state(state) \ + ((state) < LIT_STATES) + + +///////////// +// Literal // +///////////// + +/// Each literal coder is divided in three sections: +/// - 0x001-0x0FF: Without match byte +/// - 0x101-0x1FF: With match byte; match bit is 0 +/// - 0x201-0x2FF: With match byte; match bit is 1 +/// +/// Match byte is used when the previous LZMA symbol was something else than +/// a literal (that is, it was some kind of match). +#define LITERAL_CODER_SIZE 0x300 + +/// Maximum number of literal coders +#define LITERAL_CODERS_MAX (1 << LZMA_LCLP_MAX) + +/// Locate the literal coder for the next literal byte. The choice depends on +/// - the lowest literal_pos_bits bits of the position of the current +/// byte; and +/// - the highest literal_context_bits bits of the previous byte. +#define literal_subcoder(probs, lc, lp_mask, pos, prev_byte) \ + ((probs)[(((pos) & lp_mask) << lc) + ((prev_byte) >> (8 - lc))]) + + +static inline void +literal_init(probability (*probs)[LITERAL_CODER_SIZE], + uint32_t lc, uint32_t lp) +{ + assert(lc + lp <= LZMA_LCLP_MAX); + + const uint32_t coders = 1U << (lc + lp); + + for (uint32_t i = 0; i < coders; ++i) + for (uint32_t j = 0; j < LITERAL_CODER_SIZE; ++j) + bit_reset(probs[i][j]); + + return; +} + + +////////////////// +// Match length // +////////////////// + +// Minimum length of a match is two bytes. +#define MATCH_LEN_MIN 2 + +// Match length is encoded with 4, 5, or 10 bits. +// +// Length Bits +// 2-9 4 = Choice=0 + 3 bits +// 10-17 5 = Choice=1 + Choice2=0 + 3 bits +// 18-273 10 = Choice=1 + Choice2=1 + 8 bits +#define LEN_LOW_BITS 3 +#define LEN_LOW_SYMBOLS (1 << LEN_LOW_BITS) +#define LEN_MID_BITS 3 +#define LEN_MID_SYMBOLS (1 << LEN_MID_BITS) +#define LEN_HIGH_BITS 8 +#define LEN_HIGH_SYMBOLS (1 << LEN_HIGH_BITS) +#define LEN_SYMBOLS (LEN_LOW_SYMBOLS + LEN_MID_SYMBOLS + LEN_HIGH_SYMBOLS) + +// Maximum length of a match is 273 which is a result of the encoding +// described above. +#define MATCH_LEN_MAX (MATCH_LEN_MIN + LEN_SYMBOLS - 1) + + +//////////////////// +// Match distance // +//////////////////// + +// Different set of probabilities is used for match distances that have very +// short match length: Lengths of 2, 3, and 4 bytes have a separate set of +// probabilities for each length. The matches with longer length use a shared +// set of probabilities. +#define LEN_TO_POS_STATES 4 + +// Macro to get the index of the appropriate probability array. +#define get_len_to_pos_state(len) \ + ((len) < LEN_TO_POS_STATES + MATCH_LEN_MIN \ + ? (len) - MATCH_LEN_MIN \ + : LEN_TO_POS_STATES - 1) + +// The highest two bits of a match distance (pos slot) are encoded using six +// bits. See fastpos.h for more explanation. +#define POS_SLOT_BITS 6 +#define POS_SLOTS (1 << POS_SLOT_BITS) + +// Match distances up to 127 are fully encoded using probabilities. Since +// the highest two bits (pos slot) are always encoded using six bits, the +// distances 0-3 don't need any additional bits to encode, since the pos +// slot itself is the same as the actual distance. START_POS_MODEL_INDEX +// indicates the first pos slot where at least one additional bit is needed. +#define START_POS_MODEL_INDEX 4 + +// Match distances greater than 127 are encoded in three pieces: +// - pos slot: the highest two bits +// - direct bits: 2-26 bits below the highest two bits +// - alignment bits: four lowest bits +// +// Direct bits don't use any probabilities. +// +// The pos slot value of 14 is for distances 128-191 (see the table in +// fastpos.h to understand why). +#define END_POS_MODEL_INDEX 14 + +// Pos slots that indicate a distance <= 127. +#define FULL_DISTANCES_BITS (END_POS_MODEL_INDEX / 2) +#define FULL_DISTANCES (1 << FULL_DISTANCES_BITS) + +// For match distances greater than 127, only the highest two bits and the +// lowest four bits (alignment) is encoded using probabilities. +#define ALIGN_BITS 4 +#define ALIGN_TABLE_SIZE (1 << ALIGN_BITS) +#define ALIGN_MASK (ALIGN_TABLE_SIZE - 1) + +// LZMA remembers the four most recent match distances. Reusing these distances +// tends to take less space than re-encoding the actual distance value. +#define REP_DISTANCES 4 + +#endif |