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 */
112