xz-archive/src/liblzma/lzma/lzma_common.h

///////////////////////////////////////////////////////////////////////////////
//
/// \file       lzma_common.h
/// \brief      Private definitions common to LZMA encoder and decoder
//
//  Copyright (C) 1999-2006 Igor Pavlov
//  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_LZMA_COMMON_H
#define LZMA_LZMA_COMMON_H

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


///////////////
// Constants //
///////////////

#define REP_DISTANCES 4
#define STATES 12
#define LIT_STATES 7

#define POS_SLOT_BITS 6
#define DICT_LOG_SIZE_MAX 30
#define DIST_TABLE_SIZE_MAX (DICT_LOG_SIZE_MAX * 2)
#if (UINT32_C(1) << DICT_LOG_SIZE_MAX) != LZMA_DICTIONARY_SIZE_MAX
#	error DICT_LOG_SIZE_MAX is inconsistent with LZMA_DICTIONARY_SIZE_MAX
#endif

// 2 is for speed optimization
#define LEN_TO_POS_STATES_BITS 2
#define LEN_TO_POS_STATES (1 << LEN_TO_POS_STATES_BITS)

#define MATCH_MIN_LEN 2

#define ALIGN_BITS 4
#define ALIGN_TABLE_SIZE (1 << ALIGN_BITS)
#define ALIGN_MASK (ALIGN_TABLE_SIZE - 1)

#define START_POS_MODEL_INDEX 4
#define END_POS_MODEL_INDEX 14
#define POS_MODELS (END_POS_MODEL_INDEX - START_POS_MODEL_INDEX)

#define FULL_DISTANCES (1 << (END_POS_MODEL_INDEX / 2))

#define LIT_POS_STATES_BITS_MAX LZMA_LITERAL_POS_BITS_MAX
#define LIT_CONTEXT_BITS_MAX LZMA_LITERAL_CONTEXT_BITS_MAX

#define POS_STATES_BITS_MAX LZMA_POS_BITS_MAX
#define POS_STATES_MAX (1 << POS_STATES_BITS_MAX)


// Length coder & Length price table encoder
#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 LEN_SPEC_SYMBOLS (LOW_LOW_SYMBOLS + LEN_MID_LEN_SYMBOLS)
#define MATCH_MAX_LEN (MATCH_MIN_LEN + LEN_SYMBOLS - 1)

// Total number of probs in a Len Encoder
#define LEN_CODER_TOTAL_PROBS (LEN_HIGH_CODER + LEN_HIGH_SYMBOLS)

// Price table size of Len Encoder
#define LEN_PRICES (LEN_SYMBOLS << POS_STATES_BITS_MAX)

// Special lengths used together with distance == UINT32_MAX
#define LEN_SPECIAL_EOPM MATCH_MIN_LEN
#define LEN_SPECIAL_FLUSH (LEN_SPECIAL_EOPM + 1)


// Optimal - Number of entries in the optimum array.
#define OPTS (1 << 12)


// Miscellaneous
#define INFINITY_PRICE 0x0FFFFFFF


////////////
// Macros //
////////////

#define get_len_to_pos_state(len) \
	((len) < LEN_TO_POS_STATES + MATCH_MIN_LEN \
		? (len) - MATCH_MIN_LEN \
		: LEN_TO_POS_STATES - 1)


///////////
// State //
///////////

// Used for updating strm->data->state in both encoder and decoder.

#define update_char(index) \
	index = ((index) < 4 \
			? 0 \
			: ((index) < 10 \
				? (index) - 3 \
				: (index) - 6))

#define update_match(index) \
	index = ((index) < LIT_STATES ? 7 : 10)

#define update_rep(index) \
	index = ((index) < LIT_STATES ? 8 : 11)

#define update_short_rep(index) \
	index = ((index) < LIT_STATES ? 9 : 11)

#define is_char_state(index) \
	((index) < LIT_STATES)

#endif