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