1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-only 2 /* 3 * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc. 4 * All rights reserved. 5 * 6 * This source code is licensed under both the BSD-style license (found in the 7 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 8 * in the COPYING file in the root directory of this source tree). 9 * You may select, at your option, one of the above-listed licenses. 10 */ 11 12 #ifndef ZSTD_LDM_H 13 #define ZSTD_LDM_H 14 15 #if defined (__cplusplus) 16 extern "C" { 17 #endif 18 19 #include "zstd_compress_internal.h" /* ldmParams_t, U32 */ 20 #include "../zstd.h" /* ZSTD_CCtx, size_t */ 21 22 /*-************************************* 23 * Long distance matching 24 ***************************************/ 25 26 #define ZSTD_LDM_DEFAULT_WINDOW_LOG ZSTD_WINDOWLOG_LIMIT_DEFAULT 27 28 void ZSTD_ldm_fillHashTable( 29 ldmState_t* state, const BYTE* ip, 30 const BYTE* iend, ldmParams_t const* params); 31 32 /** 33 * ZSTD_ldm_generateSequences(): 34 * 35 * Generates the sequences using the long distance match finder. 36 * Generates long range matching sequences in `sequences`, which parse a prefix 37 * of the source. `sequences` must be large enough to store every sequence, 38 * which can be checked with `ZSTD_ldm_getMaxNbSeq()`. 39 * @returns 0 or an error code. 40 * 41 * NOTE: The user must have called ZSTD_window_update() for all of the input 42 * they have, even if they pass it to ZSTD_ldm_generateSequences() in chunks. 43 * NOTE: This function returns an error if it runs out of space to store 44 * sequences. 45 */ 46 size_t ZSTD_ldm_generateSequences( 47 ldmState_t* ldms, rawSeqStore_t* sequences, 48 ldmParams_t const* params, void const* src, size_t srcSize); 49 50 /** 51 * ZSTD_ldm_blockCompress(): 52 * 53 * Compresses a block using the predefined sequences, along with a secondary 54 * block compressor. The literals section of every sequence is passed to the 55 * secondary block compressor, and those sequences are interspersed with the 56 * predefined sequences. Returns the length of the last literals. 57 * Updates `rawSeqStore.pos` to indicate how many sequences have been consumed. 58 * `rawSeqStore.seq` may also be updated to split the last sequence between two 59 * blocks. 60 * @return The length of the last literals. 61 * 62 * NOTE: The source must be at most the maximum block size, but the predefined 63 * sequences can be any size, and may be longer than the block. In the case that 64 * they are longer than the block, the last sequences may need to be split into 65 * two. We handle that case correctly, and update `rawSeqStore` appropriately. 66 * NOTE: This function does not return any errors. 67 */ 68 size_t ZSTD_ldm_blockCompress(rawSeqStore_t* rawSeqStore, 69 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 70 void const* src, size_t srcSize); 71 72 /** 73 * ZSTD_ldm_skipSequences(): 74 * 75 * Skip past `srcSize` bytes worth of sequences in `rawSeqStore`. 76 * Avoids emitting matches less than `minMatch` bytes. 77 * Must be called for data with is not passed to ZSTD_ldm_blockCompress(). 78 */ 79 void ZSTD_ldm_skipSequences(rawSeqStore_t* rawSeqStore, size_t srcSize, 80 U32 const minMatch); 81 82 83 /** ZSTD_ldm_getTableSize() : 84 * Estimate the space needed for long distance matching tables or 0 if LDM is 85 * disabled. 86 */ 87 size_t ZSTD_ldm_getTableSize(ldmParams_t params); 88 89 /** ZSTD_ldm_getSeqSpace() : 90 * Return an upper bound on the number of sequences that can be produced by 91 * the long distance matcher, or 0 if LDM is disabled. 92 */ 93 size_t ZSTD_ldm_getMaxNbSeq(ldmParams_t params, size_t maxChunkSize); 94 95 /** ZSTD_ldm_adjustParameters() : 96 * If the params->hashRateLog 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 */ 104 void 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