187 lines
5.6 KiB
C
187 lines
5.6 KiB
C
/*
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* shrink_context.h - compression context definitions
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*
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* Copyright (C) 2019 Emmanuel Marty
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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* 3. This notice may not be removed or altered from any source distribution.
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*/
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/*
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* Uses the libdivsufsort library Copyright (c) 2003-2008 Yuta Mori
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*
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* Inspired by LZ4 by Yann Collet. https://github.com/lz4/lz4
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* With help, ideas, optimizations and speed measurements by spke <zxintrospec@gmail.com>
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* With ideas from Lizard by Przemyslaw Skibinski and Yann Collet. https://github.com/inikep/lizard
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* Also with ideas from smallz4 by Stephan Brumme. https://create.stephan-brumme.com/smallz4/
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*
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*/
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#ifndef _SHRINK_CONTEXT_H
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#define _SHRINK_CONTEXT_H
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#include "divsufsort.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define LCP_BITS 14
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#define TAG_BITS 4
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#define LCP_MAX ((1U<<(LCP_BITS - TAG_BITS)) - 1)
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#define LCP_AND_TAG_MAX (1U<<(LCP_BITS - 1))
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#define LCP_SHIFT (31-LCP_BITS)
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#define LCP_MASK (((1U<<LCP_BITS) - 1) << LCP_SHIFT)
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#define POS_MASK ((1U<<LCP_SHIFT) - 1)
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#define VISITED_FLAG 0x80000000
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#define EXCL_VISITED_MASK 0x7fffffff
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#define NARRIVALS_PER_POSITION_V1 8
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#define NARRIVALS_PER_POSITION_V2_SMALL 9
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#define NARRIVALS_PER_POSITION_V2_BIG 32
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#define NARRIVALS_PER_POSITION_V2_MAX 64
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#define ARRIVALS_PER_POSITION_SHIFT_V1 3
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#define ARRIVALS_PER_POSITION_SHIFT_V2 6
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#define NMATCHES_PER_INDEX_V1 16
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#define MATCHES_PER_INDEX_SHIFT_V1 4
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#define NMATCHES_PER_INDEX_V2 64
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#define MATCHES_PER_INDEX_SHIFT_V2 6
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#define LEAVE_ALONE_MATCH_SIZE 300
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#define LEAVE_ALONE_MATCH_SIZE_SMALL 1000
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#define MODESWITCH_PENALTY 3
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/** One match */
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typedef struct _lzsa_match {
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unsigned short length;
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unsigned short offset;
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} lzsa_match;
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/** Forward arrival slot */
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typedef struct _lzsa_arrival {
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int cost;
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unsigned short rep_offset;
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short from_slot;
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unsigned short from_pos;
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unsigned short rep_len;
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unsigned short match_len;
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unsigned short num_literals;
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int rep_pos;
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int score;
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} lzsa_arrival;
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/** Compression statistics */
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typedef struct _lzsa_stats {
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int min_literals;
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int max_literals;
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int total_literals;
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int min_offset;
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int max_offset;
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int num_rep_offsets;
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int total_offsets;
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int min_match_len;
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int max_match_len;
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int total_match_lens;
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int min_rle1_len;
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int max_rle1_len;
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int total_rle1_lens;
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int min_rle2_len;
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int max_rle2_len;
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int total_rle2_lens;
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int literals_divisor;
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int match_divisor;
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int rle1_divisor;
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int rle2_divisor;
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} lzsa_stats;
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/** Compression context */
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typedef struct _lzsa_compressor {
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divsufsort_ctx_t divsufsort_context;
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unsigned int *intervals;
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unsigned int *pos_data;
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unsigned int *open_intervals;
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lzsa_match *match;
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lzsa_match *best_match;
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lzsa_arrival *arrival;
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unsigned char *rep_slot_handled_mask;
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unsigned char *rep_len_handled_mask;
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int *first_offset_for_byte;
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int *next_offset_for_pos;
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int *offset_cache;
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int min_match_size;
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int format_version;
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int flags;
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int safe_dist;
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int num_commands;
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lzsa_stats stats;
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} lzsa_compressor;
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/**
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* Initialize compression context
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*
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* @param pCompressor compression context to initialize
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* @param nMaxWindowSize maximum size of input data window (previously compressed bytes + bytes to compress)
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* @param nMinMatchSize minimum match size (cannot be less than MIN_MATCH_SIZE)
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* @param nFormatVersion version of format to use (1-2)
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* @param nFlags compression flags
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*
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* @return 0 for success, non-zero for failure
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*/
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int lzsa_compressor_init(lzsa_compressor *pCompressor, const int nMaxWindowSize, const int nMinMatchSize, const int nFormatVersion, const int nFlags);
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/**
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* Clean up compression context and free up any associated resources
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*
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* @param pCompressor compression context to clean up
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*/
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void lzsa_compressor_destroy(lzsa_compressor *pCompressor);
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/**
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* Compress one block of data
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*
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* @param pCompressor compression context
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* @param pInWindow pointer to input data window (previously compressed bytes + bytes to compress)
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* @param nPreviousBlockSize number of previously compressed bytes (or 0 for none)
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* @param nInDataSize number of input bytes to compress
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* @param pOutData pointer to output buffer
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* @param nMaxOutDataSize maximum size of output buffer, in bytes
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*
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* @return size of compressed data in output buffer, or -1 if the data is uncompressible
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*/
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int lzsa_compressor_shrink_block(lzsa_compressor *pCompressor, unsigned char *pInWindow, const int nPreviousBlockSize, const int nInDataSize, unsigned char *pOutData, const int nMaxOutDataSize);
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/**
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* Get the number of compression commands issued in compressed data blocks
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*
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* @return number of commands
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*/
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int lzsa_compressor_get_command_count(lzsa_compressor *pCompressor);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _SHRINK_CONTEXT_H */
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