1/*
  2 * Copyright (c) Yann Collet, Facebook, Inc.
  3 * All rights reserved.
  4 *
  5 * This source code is licensed under both the BSD-style license (found in the
  6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
  7 * in the COPYING file in the root directory of this source tree).
  8 * You may select, at your option, one of the above-listed licenses.
  9 */
 10
 11#ifndef ZSTD_LDM_H
 12#define ZSTD_LDM_H
 13
 14
 15#include "zstd_compress_internal.h"   /* ldmParams_t, U32 */
 16#include <linux/zstd.h>   /* ZSTD_CCtx, size_t */
 17
 18/*-*************************************
 19*  Long distance matching
 20***************************************/
 21
 22#define ZSTD_LDM_DEFAULT_WINDOW_LOG ZSTD_WINDOWLOG_LIMIT_DEFAULT
 23
 24void ZSTD_ldm_fillHashTable(
 25            ldmState_t* state, const BYTE* ip,
 26            const BYTE* iend, ldmParams_t const* params);
 27
 28/*
 29 * ZSTD_ldm_generateSequences():
 30 *
 31 * Generates the sequences using the long distance match finder.
 32 * Generates long range matching sequences in `sequences`, which parse a prefix
 33 * of the source. `sequences` must be large enough to store every sequence,
 34 * which can be checked with `ZSTD_ldm_getMaxNbSeq()`.
 35 * @returns 0 or an error code.
 36 *
 37 * NOTE: The user must have called ZSTD_window_update() for all of the input
 38 * they have, even if they pass it to ZSTD_ldm_generateSequences() in chunks.
 39 * NOTE: This function returns an error if it runs out of space to store
 40 *       sequences.
 41 */
 42size_t ZSTD_ldm_generateSequences(
 43            ldmState_t* ldms, rawSeqStore_t* sequences,
 44            ldmParams_t const* params, void const* src, size_t srcSize);
 45
 46/*
 47 * ZSTD_ldm_blockCompress():
 48 *
 49 * Compresses a block using the predefined sequences, along with a secondary
 50 * block compressor. The literals section of every sequence is passed to the
 51 * secondary block compressor, and those sequences are interspersed with the
 52 * predefined sequences. Returns the length of the last literals.
 53 * Updates `rawSeqStore.pos` to indicate how many sequences have been consumed.
 54 * `rawSeqStore.seq` may also be updated to split the last sequence between two
 55 * blocks.
 56 * @return The length of the last literals.
 57 *
 58 * NOTE: The source must be at most the maximum block size, but the predefined
 59 * sequences can be any size, and may be longer than the block. In the case that
 60 * they are longer than the block, the last sequences may need to be split into
 61 * two. We handle that case correctly, and update `rawSeqStore` appropriately.
 62 * NOTE: This function does not return any errors.
 63 */
 64size_t ZSTD_ldm_blockCompress(rawSeqStore_t* rawSeqStore,
 65            ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
 66            ZSTD_paramSwitch_e useRowMatchFinder,
 67            void const* src, size_t srcSize);
 68
 69/*
 70 * ZSTD_ldm_skipSequences():
 71 *
 72 * Skip past `srcSize` bytes worth of sequences in `rawSeqStore`.
 73 * Avoids emitting matches less than `minMatch` bytes.
 74 * Must be called for data that is not passed to ZSTD_ldm_blockCompress().
 75 */
 76void ZSTD_ldm_skipSequences(rawSeqStore_t* rawSeqStore, size_t srcSize,
 77    U32 const minMatch);
 78
 79/* ZSTD_ldm_skipRawSeqStoreBytes():
 80 * Moves forward in rawSeqStore by nbBytes, updating fields 'pos' and 'posInSequence'.
 81 * Not to be used in conjunction with ZSTD_ldm_skipSequences().
 82 * Must be called for data with is not passed to ZSTD_ldm_blockCompress().
 83 */
 84void ZSTD_ldm_skipRawSeqStoreBytes(rawSeqStore_t* rawSeqStore, size_t nbBytes);
 85
 86/* ZSTD_ldm_getTableSize() :
 87 *  Estimate the space needed for long distance matching tables or 0 if LDM is
 88 *  disabled.
 89 */
 90size_t ZSTD_ldm_getTableSize(ldmParams_t params);
 91
 92/* ZSTD_ldm_getSeqSpace() :
 93 *  Return an upper bound on the number of sequences that can be produced by
 94 *  the long distance matcher, or 0 if LDM is disabled.
 95 */
 96size_t ZSTD_ldm_getMaxNbSeq(ldmParams_t params, size_t maxChunkSize);
 97
 98/* ZSTD_ldm_adjustParameters() :
 99 *  If the params->hashRateLog is not set, set it to its default value based on
100 *  windowLog and params->hashLog.
101 *
102 *  Ensures that params->bucketSizeLog is <= params->hashLog (setting it to
103 *  params->hashLog if it is not).
104 *
105 *  Ensures that the minMatchLength >= targetLength during optimal parsing.
106 */
107void ZSTD_ldm_adjustParameters(ldmParams_t* params,
108                               ZSTD_compressionParameters const* cParams);
109
110
111#endif /* ZSTD_FAST_H */