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 | |
24 | void 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 | */ |
42 | size_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 | */ |
64 | size_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 | */ |
76 | void 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 | */ |
84 | void 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 | */ |
90 | size_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 | */ |
96 | size_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 | */ |
107 | void ZSTD_ldm_adjustParameters(ldmParams_t* params, |
108 | ZSTD_compressionParameters const* cParams); |
109 | |
110 | |
111 | #endif /* ZSTD_FAST_H */ |
112 | |