140 lines
5.1 KiB
C
Executable File
140 lines
5.1 KiB
C
Executable File
/*
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* lib.h - LZSA library 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 _LIB_H
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#define _LIB_H
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#include "divsufsort.h"
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/* Compression flags */
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#define LZSA_FLAG_FAVOR_RATIO (1<<0) /**< 1 to compress with the best ratio, 0 to trade some compression ratio for extra decompression speed */
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#define LZSA_FLAG_RAW_BLOCK (1<<1) /**< 1 to emit raw block */
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#define LCP_BITS 15
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#define LCP_MAX (1<<(LCP_BITS - 1))
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#define LCP_SHIFT (32-LCP_BITS)
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#define LCP_MASK (((1<<LCP_BITS) - 1) << LCP_SHIFT)
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#define POS_MASK ((1<<LCP_SHIFT) - 1)
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#define NMATCHES_PER_OFFSET 8
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#define MATCHES_PER_OFFSET_SHIFT 3
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#define LEAVE_ALONE_MATCH_SIZE 1000
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#define LAST_MATCH_OFFSET 4
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#define LAST_LITERALS 1
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#define MODESWITCH_PENALTY 1
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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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typedef struct _lzsa_repmatch_opt {
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int incoming_offset;
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short best_slot_for_incoming;
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short expected_repmatch;
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} lzsa_repmatch_opt;
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/** Compression context */
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typedef struct _lsza_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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int *slot_cost;
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lzsa_repmatch_opt *repmatch_opt;
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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 num_commands;
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} lsza_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 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(lsza_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(lsza_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_shrink_block(lsza_compressor *pCompressor, const 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(lsza_compressor *pCompressor);
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/**
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* Decompress one data block
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*
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* @param pInBlock pointer to compressed data
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* @param nInBlockSize size of compressed data, in bytes
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* @param pOutData pointer to output decompression buffer (previously decompressed bytes + room for decompressing this block)
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* @param nOutDataOffset starting index of where to store decompressed bytes in output buffer (and size of previously decompressed bytes)
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* @param nBlockMaxSize total size of output decompression buffer, in bytes
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*
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* @return size of decompressed data in bytes, or -1 for error
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*/
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int lzsa_expand_block(const int nFormatVersion, const unsigned char *pInBlock, int nBlockSize, unsigned char *pOutData, int nOutDataOffset, int nBlockMaxSize);
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#endif /* _LIB_H */
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