TOMOYO Linux Cross Reference
Linux/lib/zstd/compress/zstd_ldm.h

   /*
    * Copyright (c) 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).
    * You may select, at your option, one of the above-listed licenses.
    */
  
  #ifndef ZSTD_LDM_H
  #define ZSTD_LDM_H
  
  
  #include "zstd_compress_internal.h"   /* ldmParams_t, U32 */
  #include <linux/zstd.h>   /* ZSTD_CCtx, size_t */
  
  /*-*************************************
  *  Long distance matching
  ***************************************/
  
  #define ZSTD_LDM_DEFAULT_WINDOW_LOG ZSTD_WINDOWLOG_LIMIT_DEFAULT
  
  void ZSTD_ldm_fillHashTable(
              ldmState_t* state, const BYTE* ip,
              const BYTE* iend, ldmParams_t const* params);
  
  /*
   * ZSTD_ldm_generateSequences():
   *
   * Generates the sequences using the long distance match finder.
   * Generates long range matching sequences in `sequences`, which parse a prefix
   * of the source. `sequences` must be large enough to store every sequence,
   * which can be checked with `ZSTD_ldm_getMaxNbSeq()`.
   * @returns 0 or an error code.
   *
   * NOTE: The user must have called ZSTD_window_update() for all of the input
   * they have, even if they pass it to ZSTD_ldm_generateSequences() in chunks.
   * NOTE: This function returns an error if it runs out of space to store
   *       sequences.
   */
  size_t ZSTD_ldm_generateSequences(
              ldmState_t* ldms, rawSeqStore_t* sequences,
              ldmParams_t const* params, void const* src, size_t srcSize);
  
  /*
   * ZSTD_ldm_blockCompress():
   *
   * Compresses a block using the predefined sequences, along with a secondary
   * block compressor. The literals section of every sequence is passed to the
   * secondary block compressor, and those sequences are interspersed with the
   * predefined sequences. Returns the length of the last literals.
   * Updates `rawSeqStore.pos` to indicate how many sequences have been consumed.
   * `rawSeqStore.seq` may also be updated to split the last sequence between two
   * blocks.
   * @return The length of the last literals.
   *
   * NOTE: The source must be at most the maximum block size, but the predefined
   * sequences can be any size, and may be longer than the block. In the case that
   * they are longer than the block, the last sequences may need to be split into
   * two. We handle that case correctly, and update `rawSeqStore` appropriately.
   * NOTE: This function does not return any errors.
   */
  size_t ZSTD_ldm_blockCompress(rawSeqStore_t* rawSeqStore,
              ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
              ZSTD_paramSwitch_e useRowMatchFinder,
              void const* src, size_t srcSize);
  
  /*
   * ZSTD_ldm_skipSequences():
   *
   * Skip past `srcSize` bytes worth of sequences in `rawSeqStore`.
   * Avoids emitting matches less than `minMatch` bytes.
   * Must be called for data that is not passed to ZSTD_ldm_blockCompress().
   */
  void ZSTD_ldm_skipSequences(rawSeqStore_t* rawSeqStore, size_t srcSize,
      U32 const minMatch);
  
  /* ZSTD_ldm_skipRawSeqStoreBytes():
   * Moves forward in rawSeqStore by nbBytes, updating fields 'pos' and 'posInSequence'.
   * Not to be used in conjunction with ZSTD_ldm_skipSequences().
   * Must be called for data with is not passed to ZSTD_ldm_blockCompress().
   */
  void ZSTD_ldm_skipRawSeqStoreBytes(rawSeqStore_t* rawSeqStore, size_t nbBytes);
  
  /* ZSTD_ldm_getTableSize() :
   *  Estimate the space needed for long distance matching tables or 0 if LDM is
   *  disabled.
   */
  size_t ZSTD_ldm_getTableSize(ldmParams_t params);
  
  /* ZSTD_ldm_getSeqSpace() :
   *  Return an upper bound on the number of sequences that can be produced by
   *  the long distance matcher, or 0 if LDM is disabled.
   */
  size_t ZSTD_ldm_getMaxNbSeq(ldmParams_t params, size_t maxChunkSize);
  
  /* ZSTD_ldm_adjustParameters() :
   *  If the params->hashRateLog 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).
  *
  *  Ensures that the minMatchLength >= targetLength during optimal parsing.
  */
 void ZSTD_ldm_adjustParameters(ldmParams_t* params,
                                ZSTD_compressionParameters const* cParams);
 
 
 #endif /* ZSTD_FAST_H */
 

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