68 lines
2.3 KiB
C
68 lines
2.3 KiB
C
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/*
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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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#include "zstd_compress.h"
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#if defined (__cplusplus)
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extern "C" {
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#endif
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/*-*************************************
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* Long distance matching
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***************************************/
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#define ZSTD_LDM_WINDOW_LOG 27
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#define ZSTD_LDM_HASHEVERYLOG_NOTSET 9999
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/** ZSTD_compressBlock_ldm_generic() :
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*
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* This is a block compressor intended for long distance matching.
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*
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* The function searches for matches of length at least
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* ldmParams.minMatchLength using a hash table in cctx->ldmState.
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* Matches can be at a distance of up to cParams.windowLog.
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*
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* Upon finding a match, the unmatched literals are compressed using a
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* ZSTD_blockCompressor (depending on the strategy in the compression
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* parameters), which stores the matched sequences. The "long distance"
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* match is then stored with the remaining literals from the
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* ZSTD_blockCompressor. */
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size_t ZSTD_compressBlock_ldm(ZSTD_CCtx* cctx, const void* src, size_t srcSize);
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size_t ZSTD_compressBlock_ldm_extDict(ZSTD_CCtx* ctx,
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const void* src, size_t srcSize);
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/** ZSTD_ldm_initializeParameters() :
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* Initialize the long distance matching parameters to their default values. */
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size_t ZSTD_ldm_initializeParameters(ldmParams_t* params, U32 enableLdm);
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/** ZSTD_ldm_getTableSize() :
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* Estimate the space needed for long distance matching tables. */
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size_t ZSTD_ldm_getTableSize(U32 hashLog, U32 bucketSizeLog);
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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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void ZSTD_ldm_adjustParameters(ldmParams_t* params, U32 windowLog);
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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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