1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
/*
* Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
*/
#ifndef ZSTD_LDM_H
#define ZSTD_LDM_H
#if defined (__cplusplus)
extern "C" {
#endif
#include "zstd_compress_internal.h" /* ldmParams_t, U32 */
#include "zstd.h" /* ZSTD_CCtx, size_t */
/*-*************************************
* Long distance matching
***************************************/
#define ZSTD_LDM_DEFAULT_WINDOW_LOG ZSTD_WINDOWLOG_DEFAULTMAX
#define ZSTD_LDM_HASHEVERYLOG_NOTSET 9999
/** ZSTD_compressBlock_ldm_generic() :
*
* This is a block compressor intended for long distance matching.
*
* The function searches for matches of length at least
* ldmParams.minMatchLength using a hash table in cctx->ldmState.
* Matches can be at a distance of up to cParams.windowLog.
*
* Upon finding a match, the unmatched literals are compressed using a
* ZSTD_blockCompressor (depending on the strategy in the compression
* parameters), which stores the matched sequences. The "long distance"
* match is then stored with the remaining literals from the
* ZSTD_blockCompressor. */
size_t ZSTD_compressBlock_ldm(ZSTD_CCtx* cctx, const void* src, size_t srcSize);
size_t ZSTD_compressBlock_ldm_extDict(ZSTD_CCtx* ctx,
const void* src, size_t srcSize);
/** ZSTD_ldm_initializeParameters() :
* Initialize the long distance matching parameters to their default values. */
size_t ZSTD_ldm_initializeParameters(ldmParams_t* params, U32 enableLdm);
/** ZSTD_ldm_getTableSize() :
* Estimate the space needed for long distance matching tables. */
size_t ZSTD_ldm_getTableSize(U32 hashLog, U32 bucketSizeLog);
/** ZSTD_ldm_getTableSize() :
* Return prime8bytes^(minMatchLength-1) */
U64 ZSTD_ldm_getHashPower(U32 minMatchLength);
/** ZSTD_ldm_adjustParameters() :
* If the params->hashEveryLog is not set, set it to its default value based on
* windowLog and params->hashLog.
*
* Ensures that params->bucketSizeLog is <= params->hashLog (setting it to
* params->hashLog if it is not). */
void ZSTD_ldm_adjustParameters(ldmParams_t* params, U32 windowLog);
#if defined (__cplusplus)
}
#endif
#endif /* ZSTD_FAST_H */