1/*
2 * Copyright (c) 2016-present, 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 */
9
10#ifndef ZSTD_LDM_H
11#define ZSTD_LDM_H
12
13#if defined (__cplusplus)
14extern "C" {
15#endif
16
17#include "zstd_compress_internal.h" /* ldmParams_t, U32 */
18#include "zstd.h" /* ZSTD_CCtx, size_t */
19
20/*-*************************************
21* Long distance matching
22***************************************/
23
24#define ZSTD_LDM_DEFAULT_WINDOW_LOG ZSTD_WINDOWLOG_DEFAULTMAX
25
26/**
27 * ZSTD_ldm_generateSequences():
28 *
29 * Generates the sequences using the long distance match finder.
30 * Generates long range matching sequences in `sequences`, which parse a prefix
31 * of the source. `sequences` must be large enough to store every sequence,
32 * which can be checked with `ZSTD_ldm_getMaxNbSeq()`.
33 * @returns 0 or an error code.
34 *
35 * NOTE: The user must have called ZSTD_window_update() for all of the input
36 * they have, even if they pass it to ZSTD_ldm_generateSequences() in chunks.
37 * NOTE: This function returns an error if it runs out of space to store
38 * sequences.
39 */
40size_t ZSTD_ldm_generateSequences(
41 ldmState_t* ldms, rawSeqStore_t* sequences,
42 ldmParams_t const* params, void const* src, size_t srcSize);
43
44/**
45 * ZSTD_ldm_blockCompress():
46 *
47 * Compresses a block using the predefined sequences, along with a secondary
48 * block compressor. The literals section of every sequence is passed to the
49 * secondary block compressor, and those sequences are interspersed with the
50 * predefined sequences. Returns the length of the last literals.
51 * Updates `rawSeqStore.pos` to indicate how many sequences have been consumed.
52 * `rawSeqStore.seq` may also be updated to split the last sequence between two
53 * blocks.
54 * @return The length of the last literals.
55 *
56 * NOTE: The source must be at most the maximum block size, but the predefined
57 * sequences can be any size, and may be longer than the block. In the case that
58 * they are longer than the block, the last sequences may need to be split into
59 * two. We handle that case correctly, and update `rawSeqStore` appropriately.
60 * NOTE: This function does not return any errors.
61 */
62size_t ZSTD_ldm_blockCompress(rawSeqStore_t* rawSeqStore,
63 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
64 ZSTD_compressionParameters const* cParams,
65 void const* src, size_t srcSize,
66 int const extDict);
67
68/**
69 * ZSTD_ldm_skipSequences():
70 *
71 * Skip past `srcSize` bytes worth of sequences in `rawSeqStore`.
72 * Avoids emitting matches less than `minMatch` bytes.
73 * Must be called for data with is not passed to ZSTD_ldm_blockCompress().
74 */
75void ZSTD_ldm_skipSequences(rawSeqStore_t* rawSeqStore, size_t srcSize,
76 U32 const minMatch);
77
78
79/** ZSTD_ldm_getTableSize() :
80 * Estimate the space needed for long distance matching tables or 0 if LDM is
81 * disabled.
82 */
83size_t ZSTD_ldm_getTableSize(ldmParams_t params);
84
85/** ZSTD_ldm_getSeqSpace() :
86 * Return an upper bound on the number of sequences that can be produced by
87 * the long distance matcher, or 0 if LDM is disabled.
88 */
89size_t ZSTD_ldm_getMaxNbSeq(ldmParams_t params, size_t maxChunkSize);
90
91/** ZSTD_ldm_getTableSize() :
92 * Return prime8bytes^(minMatchLength-1) */
93U64 ZSTD_ldm_getHashPower(U32 minMatchLength);
94
95/** ZSTD_ldm_adjustParameters() :
96 * If the params->hashEveryLog is not set, set it to its default value based on
97 * windowLog and params->hashLog.
98 *
99 * Ensures that params->bucketSizeLog is <= params->hashLog (setting it to
100 * params->hashLog if it is not).
101 *
102 * Ensures that the minMatchLength >= targetLength during optimal parsing.
103 */
104void ZSTD_ldm_adjustParameters(ldmParams_t* params,
105 ZSTD_compressionParameters const* cParams);
106
107#if defined (__cplusplus)
108}
109#endif
110
111#endif /* ZSTD_FAST_H */
112