/* * Copyright (c) Meta Platforms, Inc. and affiliates. * 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). * You may select, at your option, one of the above-listed licenses. */ #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_LIMIT_DEFAULT void ZSTD_ldm_fillHashTable( ldmState_t* state, const BYTE* ip, const BYTE* iend, ldmParams_t const* params); /** * 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], ZSTD_paramSwitch_e useRowMatchFinder, void const* src, size_t srcSize); /** * ZSTD_ldm_skipSequences(): * * Skip past `srcSize` bytes worth of sequences in `rawSeqStore`. * Avoids emitting matches less than `minMatch` bytes. * Must be called for data that is not passed to ZSTD_ldm_blockCompress(). */ void ZSTD_ldm_skipSequences(rawSeqStore_t* rawSeqStore, size_t srcSize, U32 const minMatch); /* ZSTD_ldm_skipRawSeqStoreBytes(): * Moves forward in rawSeqStore by nbBytes, updating fields 'pos' and 'posInSequence'. * Not to be used in conjunction with ZSTD_ldm_skipSequences(). * Must be called for data with is not passed to ZSTD_ldm_blockCompress(). */ void ZSTD_ldm_skipRawSeqStoreBytes(rawSeqStore_t* rawSeqStore, size_t nbBytes); /** 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_adjustParameters() : * If the params->hashRateLog 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 */