lzma_common.h File Reference

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

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

Go to the source code of this file.

Macros
#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)
	Indicate that the latest state was a match.
#define	update_long_rep(state)
	Indicate that the latest state was a long repeated match.
#define	update_short_rep(state)
	Indicate that the latest state was a short match.
#define	is_literal_state(state)
	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)
#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	DIST_STATES   4
#define	get_dist_state(len)
#define	DIST_SLOT_BITS   6
#define	DIST_SLOTS   (1 << DIST_SLOT_BITS)
#define	DIST_MODEL_START   4
#define	DIST_MODEL_END   14
#define	FULL_DISTANCES_BITS   (DIST_MODEL_END / 2)
#define	FULL_DISTANCES   (1 << FULL_DISTANCES_BITS)
#define	ALIGN_BITS   4
#define	ALIGN_SIZE   (1 << ALIGN_BITS)
#define	ALIGN_MASK   (ALIGN_SIZE - 1)
#define	REPS   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 }

Detailed Description

Private definitions common to LZMA encoder and decoder.

Macro Definition Documentation

ALIGN_BITS

#define ALIGN_BITS   4

ALIGN_MASK

#define ALIGN_MASK   (ALIGN_SIZE - 1)

ALIGN_SIZE

#define ALIGN_SIZE   (1 << ALIGN_BITS)

DIST_MODEL_END

#define DIST_MODEL_END   14

DIST_MODEL_START

#define DIST_MODEL_START   4

DIST_SLOT_BITS

#define DIST_SLOT_BITS   6

DIST_SLOTS

#define DIST_SLOTS   (1 << DIST_SLOT_BITS)

DIST_STATES

#define DIST_STATES   4

FULL_DISTANCES

#define FULL_DISTANCES   (1 << FULL_DISTANCES_BITS)

FULL_DISTANCES_BITS

#define FULL_DISTANCES_BITS   (DIST_MODEL_END / 2)

get_dist_state

#define get_dist_state

(

len

)

Value:

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

is_literal_state

#define is_literal_state

(

state

)

Value:

    ((state) < LIT_STATES)

Test if the previous state was a literal.

LEN_HIGH_BITS

#define LEN_HIGH_BITS   8

LEN_HIGH_SYMBOLS

#define LEN_HIGH_SYMBOLS   (1 << LEN_HIGH_BITS)

LEN_LOW_BITS

#define LEN_LOW_BITS   3

LEN_LOW_SYMBOLS

#define LEN_LOW_SYMBOLS   (1 << LEN_LOW_BITS)

LEN_MID_BITS

#define LEN_MID_BITS   3

LEN_MID_SYMBOLS

#define LEN_MID_SYMBOLS   (1 << LEN_MID_BITS)

LEN_SYMBOLS

#define LEN_SYMBOLS   (LEN_LOW_SYMBOLS + LEN_MID_SYMBOLS + LEN_HIGH_SYMBOLS)

LIT_STATES

#define LIT_STATES   7

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

LITERAL_CODER_SIZE

#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).

LITERAL_CODERS_MAX

#define LITERAL_CODERS_MAX   (1 << LZMA_LCLP_MAX)

Maximum number of literal coders.

literal_subcoder

#define literal_subcoder	(		probs,
			lc,
			lp_mask,
			pos,
			prev_byte )

Value:

    ((probs)[(((pos) & (lp_mask)) << (lc)) \
            + ((uint32_t)(prev_byte) >> (8U - (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.

MATCH_LEN_MAX

#define MATCH_LEN_MAX   (MATCH_LEN_MIN + LEN_SYMBOLS - 1)

MATCH_LEN_MIN

#define MATCH_LEN_MIN   2

POS_STATES_MAX

#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.

REPS

#define REPS   4

STATES

#define STATES   12

Total number of states.

update_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.

update_long_rep

#define update_long_rep

(

state

)

Value:

    state = ((state) < LIT_STATES ? STATE_LIT_LONGREP : STATE_NONLIT_REP)

Indicate that the latest state was a long repeated match.

update_match

#define update_match

(

state

)

Value:

    state = ((state) < LIT_STATES ? STATE_LIT_MATCH : STATE_NONLIT_MATCH)

Indicate that the latest state was a match.

update_short_rep

#define update_short_rep

(

state

)

Value:

    state = ((state) < LIT_STATES ? STATE_LIT_SHORTREP : STATE_NONLIT_REP)

Indicate that the latest state was a short match.

Enumeration Type Documentation

lzma_lzma_state

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.

Enumerator
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