zstd_ldm.h
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| 3.9 KiB
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r37513 | /* | ||
* Copyright (c) 2016-present, Yann Collet, Facebook, Inc. | ||||
* All rights reserved. | ||||
* | ||||
* This source code is licensed under both the BSD-style license (found in the | ||||
* LICENSE file in the root directory of this source tree) and the GPLv2 (found | ||||
* in the COPYING file in the root directory of this source tree). | ||||
*/ | ||||
#ifndef ZSTD_LDM_H | ||||
#define ZSTD_LDM_H | ||||
#if defined (__cplusplus) | ||||
extern "C" { | ||||
#endif | ||||
#include "zstd_compress_internal.h" /* ldmParams_t, U32 */ | ||||
#include "zstd.h" /* ZSTD_CCtx, size_t */ | ||||
/*-************************************* | ||||
* Long distance matching | ||||
***************************************/ | ||||
#define ZSTD_LDM_DEFAULT_WINDOW_LOG ZSTD_WINDOWLOG_DEFAULTMAX | ||||
/** | ||||
* ZSTD_ldm_generateSequences(): | ||||
* | ||||
* Generates the sequences using the long distance match finder. | ||||
* Generates long range matching sequences in `sequences`, which parse a prefix | ||||
* of the source. `sequences` must be large enough to store every sequence, | ||||
* which can be checked with `ZSTD_ldm_getMaxNbSeq()`. | ||||
* @returns 0 or an error code. | ||||
* | ||||
* NOTE: The user must have called ZSTD_window_update() for all of the input | ||||
* they have, even if they pass it to ZSTD_ldm_generateSequences() in chunks. | ||||
* NOTE: This function returns an error if it runs out of space to store | ||||
* sequences. | ||||
*/ | ||||
size_t ZSTD_ldm_generateSequences( | ||||
ldmState_t* ldms, rawSeqStore_t* sequences, | ||||
ldmParams_t const* params, void const* src, size_t srcSize); | ||||
/** | ||||
* ZSTD_ldm_blockCompress(): | ||||
* | ||||
* Compresses a block using the predefined sequences, along with a secondary | ||||
* block compressor. The literals section of every sequence is passed to the | ||||
* secondary block compressor, and those sequences are interspersed with the | ||||
* predefined sequences. Returns the length of the last literals. | ||||
* Updates `rawSeqStore.pos` to indicate how many sequences have been consumed. | ||||
* `rawSeqStore.seq` may also be updated to split the last sequence between two | ||||
* blocks. | ||||
* @return The length of the last literals. | ||||
* | ||||
* NOTE: The source must be at most the maximum block size, but the predefined | ||||
* sequences can be any size, and may be longer than the block. In the case that | ||||
* they are longer than the block, the last sequences may need to be split into | ||||
* two. We handle that case correctly, and update `rawSeqStore` appropriately. | ||||
* NOTE: This function does not return any errors. | ||||
*/ | ||||
size_t ZSTD_ldm_blockCompress(rawSeqStore_t* rawSeqStore, | ||||
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], | ||||
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r40157 | void const* src, size_t srcSize); | ||
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r37513 | |||
/** | ||||
* ZSTD_ldm_skipSequences(): | ||||
* | ||||
* Skip past `srcSize` bytes worth of sequences in `rawSeqStore`. | ||||
* Avoids emitting matches less than `minMatch` bytes. | ||||
* Must be called for data with is not passed to ZSTD_ldm_blockCompress(). | ||||
*/ | ||||
void ZSTD_ldm_skipSequences(rawSeqStore_t* rawSeqStore, size_t srcSize, | ||||
U32 const minMatch); | ||||
/** ZSTD_ldm_getTableSize() : | ||||
* Estimate the space needed for long distance matching tables or 0 if LDM is | ||||
* disabled. | ||||
*/ | ||||
size_t ZSTD_ldm_getTableSize(ldmParams_t params); | ||||
/** ZSTD_ldm_getSeqSpace() : | ||||
* Return an upper bound on the number of sequences that can be produced by | ||||
* the long distance matcher, or 0 if LDM is disabled. | ||||
*/ | ||||
size_t ZSTD_ldm_getMaxNbSeq(ldmParams_t params, size_t maxChunkSize); | ||||
/** ZSTD_ldm_getTableSize() : | ||||
* Return prime8bytes^(minMatchLength-1) */ | ||||
U64 ZSTD_ldm_getHashPower(U32 minMatchLength); | ||||
/** ZSTD_ldm_adjustParameters() : | ||||
* If the params->hashEveryLog is not set, set it to its default value based on | ||||
* windowLog and params->hashLog. | ||||
* | ||||
* Ensures that params->bucketSizeLog is <= params->hashLog (setting it to | ||||
* params->hashLog if it is not). | ||||
* | ||||
* Ensures that the minMatchLength >= targetLength during optimal parsing. | ||||
*/ | ||||
void ZSTD_ldm_adjustParameters(ldmParams_t* params, | ||||
ZSTD_compressionParameters const* cParams); | ||||
#if defined (__cplusplus) | ||||
} | ||||
#endif | ||||
#endif /* ZSTD_FAST_H */ | ||||