Private definitions common to LZMA encoder and decoder. More...

#include "common.h"
#include "range_common.h"

Defines
#define	POS_STATES_MAX (1 << LZMA_PB_MAX)
#define	STATES 12
	Total number of states.
#define	LIT_STATES 7
	The lowest 7 states indicate that the previous state was a literal.
#define	update_literal(state)
	Indicate that the latest state was a literal.
#define	update_match(state) state = ((state) < LIT_STATES ? STATE_LIT_MATCH : STATE_NONLIT_MATCH)
	Indicate that the latest state was a match.
#define	update_long_rep(state) state = ((state) < LIT_STATES ? STATE_LIT_LONGREP : STATE_NONLIT_REP)
	Indicate that the latest state was a long repeated match.
#define	update_short_rep(state) state = ((state) < LIT_STATES ? STATE_LIT_SHORTREP : STATE_NONLIT_REP)
	Indicate that the latest state was a short match.
#define	is_literal_state(state) ((state) < LIT_STATES)
	Test if the previous state was a literal.
#define	LITERAL_CODER_SIZE 0x300
#define	LITERAL_CODERS_MAX (1 << LZMA_LCLP_MAX)
	Maximum number of literal coders.
#define	literal_subcoder(probs, lc, lp_mask, pos, prev_byte) ((probs)[(((pos) & lp_mask) << lc) + ((prev_byte) >> (8 - lc))])
#define	MATCH_LEN_MIN 2
#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)
#define	MATCH_LEN_MAX (MATCH_LEN_MIN + LEN_SYMBOLS - 1)
#define	LEN_TO_POS_STATES 4
#define	get_len_to_pos_state(len)
#define	POS_SLOT_BITS 6
#define	POS_SLOTS (1 << POS_SLOT_BITS)
#define	START_POS_MODEL_INDEX 4
#define	END_POS_MODEL_INDEX 14
#define	FULL_DISTANCES_BITS (END_POS_MODEL_INDEX / 2)
#define	FULL_DISTANCES (1 << FULL_DISTANCES_BITS)
#define	ALIGN_BITS 4
#define	ALIGN_TABLE_SIZE (1 << ALIGN_BITS)
#define	ALIGN_MASK (ALIGN_TABLE_SIZE - 1)
#define	REP_DISTANCES 4
Enumerations
enum	lzma_lzma_state { 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 }
Functions
static bool	is_lclppb_valid (const lzma_options_lzma *options)
	Validates lc, lp, and pb.
static void	literal_init (probability(*probs)[LITERAL_CODER_SIZE], uint32_t lc, uint32_t lp)

Detailed Description

Private definitions common to LZMA encoder and decoder.

Define Documentation

#define POS_STATES_MAX (1 << LZMA_PB_MAX)

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 STATES 12

Total number of states.

#define LIT_STATES 7

The lowest 7 states indicate that the previous state was a literal.

#define update_literal ( state )

Value:

state = ((state) <= STATE_SHORTREP_LIT_LIT \
                        ? STATE_LIT_LIT \
                        : ((state) <= STATE_LIT_SHORTREP \
                                ? (state) - 3 \
                                : (state) - 6))

Indicate that the latest state was a literal.

#define update_match ( state ) state = ((state) < LIT_STATES ? STATE_LIT_MATCH : STATE_NONLIT_MATCH)

Indicate that the latest state was a match.

#define update_long_rep ( state ) state = ((state) < LIT_STATES ? STATE_LIT_LONGREP : STATE_NONLIT_REP)

Indicate that the latest state was a long repeated match.

#define update_short_rep ( state ) state = ((state) < LIT_STATES ? STATE_LIT_SHORTREP : STATE_NONLIT_REP)

Indicate that the latest state was a short match.

#define is_literal_state ( state ) ((state) < LIT_STATES)

Test if the previous state was a literal.

#define LITERAL_CODER_SIZE 0x300

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_CODERS_MAX (1 << LZMA_LCLP_MAX)

Maximum number of literal coders.

#define literal_subcoder	(	probs,
		lc,
		lp_mask,
		pos,
		prev_byte
	)		((probs)[(((pos) & lp_mask) << lc) + ((prev_byte) >> (8 - lc))])

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 get_len_to_pos_state ( len )

Value:

((len) < LEN_TO_POS_STATES + MATCH_LEN_MIN \
                ? (len) - MATCH_LEN_MIN \
                : LEN_TO_POS_STATES - 1)

Enumeration Type Documentation

enum lzma_lzma_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.

Function Documentation

static bool is_lclppb_valid ( const lzma_options_lzma * options ) [inline, static]

Validates lc, lp, and pb.

References lzma_options_lzma::lc, lzma_options_lzma::lp, and lzma_options_lzma::pb.

Referenced by lzma_decoder_init(), and lzma_lzma_lclppb_encode().

/tmp/buildd/xz-utils-5.0.0/src/liblzma/lzma/lzma_common.h File Reference

Defines

Enumerations

Functions

Detailed Description

Define Documentation

Enumeration Type Documentation

Function Documentation