view release on metacpan or  search on metacpan

ext/zstd/doc/zstd_manual.html  view on Meta::CPAN

                              * For strategy fast:
                              *     Distance between match sampling.
                              *     Larger values make compression faster, and weaker.
                              * Special: value 0 means "use default targetLength". */
    ZSTD_c_strategy=107,     </b>/* See ZSTD_strategy enum definition.<b>
                              * The higher the value of selected strategy, the more complex it is,
                              * resulting in stronger and slower compression.
                              * Special: value 0 means "use default strategy". */

    </b>/* LDM mode parameters */<b>
    ZSTD_c_enableLongDistanceMatching=160, </b>/* Enable long distance matching.<b>
                                     * This parameter is designed to improve compression ratio
                                     * for large inputs, by finding large matches at long distance.
                                     * It increases memory usage and window size.
                                     * Note: enabling this parameter increases default ZSTD_c_windowLog to 128 MB
                                     * except when expressly set to a different value. */
    ZSTD_c_ldmHashLog=161,   </b>/* Size of the table for long distance matching, as a power of 2.<b>
                              * Larger values increase memory usage and compression ratio,
                              * but decrease compression speed.
                              * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX
                              * default: windowlog - 7.
                              * Special: value 0 means "automatically determine hashlog". */
    ZSTD_c_ldmMinMatch=162,  </b>/* Minimum match size for long distance matcher.<b>
                              * Larger/too small values usually decrease compression ratio.
                              * Must be clamped between ZSTD_LDM_MINMATCH_MIN and ZSTD_LDM_MINMATCH_MAX.
                              * Special: value 0 means "use default value" (default: 64). */
    ZSTD_c_ldmBucketSizeLog=163, </b>/* Log size of each bucket in the LDM hash table for collision resolution.<b>
                              * Larger values improve collision resolution but decrease compression speed.
                              * The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX.
                              * Special: value 0 means "use default value" (default: 3). */
    ZSTD_c_ldmHashRateLog=164, </b>/* Frequency of inserting/looking up entries into the LDM hash table.<b>
                              * Must be clamped between 0 and (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN).
                              * Default is MAX(0, (windowLog - ldmHashLog)), optimizing hash table usage.
                              * Larger values improve compression speed.
                              * Deviating far from default value will likely result in a compression ratio decrease.
                              * Special: value 0 means "automatically determine hashRateLog". */

    </b>/* frame parameters */<b>
    ZSTD_c_contentSizeFlag=200, </b>/* Content size will be written into frame header _whenever known_ (default:1)<b>
                              * Content size must be known at the beginning of compression.
                              * This is automatically the case when using ZSTD_compress2(),
                              * For streaming variants, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */
    ZSTD_c_checksumFlag=201, </b>/* A 32-bits checksum of content is written at end of frame (default:0) */<b>
    ZSTD_c_dictIDFlag=202,   </b>/* When applicable, dictionary's ID is written into frame header (default:1) */<b>

    </b>/* multi-threading parameters */<b>
    </b>/* These parameters are only useful if multi-threading is enabled (compiled with build macro ZSTD_MULTITHREAD).<b>
     * They return an error otherwise. */
    ZSTD_c_nbWorkers=400,    </b>/* Select how many threads will be spawned to compress in parallel.<b>
                              * When nbWorkers >= 1, triggers asynchronous mode when used with ZSTD_compressStream*() :
                              * ZSTD_compressStream*() consumes input and flush output if possible, but immediately gives back control to caller,
                              * while compression work is performed in parallel, within worker threads.
                              * (note : a strong exception to this rule is when first invocation of ZSTD_compressStream2() sets ZSTD_e_end :
                              *  in which case, ZSTD_compressStream2() delegates to ZSTD_compress2(), which is always a blocking call).
                              * More workers improve speed, but also increase memory usage.
                              * Default value is `0`, aka "single-threaded mode" : no worker is spawned, compression is performed inside Caller's thread, all invocations are blocking */
    ZSTD_c_jobSize=401,      </b>/* Size of a compression job. This value is enforced only when nbWorkers >= 1.<b>
                              * Each compression job is completed in parallel, so this value can indirectly impact the nb of active threads.
                              * 0 means default, which is dynamically determined based on compression parameters.
                              * Job size must be a minimum of overlap size, or 1 MB, whichever is largest.
                              * The minimum size is automatically and transparently enforced */
    ZSTD_c_overlapLog=402,   </b>/* Control the overlap size, as a fraction of window size.<b>
                              * The overlap size is an amount of data reloaded from previous job at the beginning of a new job.
                              * It helps preserve compression ratio, while each job is compressed in parallel.
                              * This value is enforced only when nbWorkers >= 1.
                              * Larger values increase compression ratio, but decrease speed.
                              * Possible values range from 0 to 9 :
                              * - 0 means "default" : value will be determined by the library, depending on strategy
                              * - 1 means "no overlap"
                              * - 9 means "full overlap", using a full window size.
                              * Each intermediate rank increases/decreases load size by a factor 2 :
                              * 9: full window;  8: w/2;  7: w/4;  6: w/8;  5:w/16;  4: w/32;  3:w/64;  2:w/128;  1:no overlap;  0:default
                              * default value varies between 6 and 9, depending on strategy */

    </b>/* note : additional experimental parameters are also available<b>
     * within the experimental section of the API.
     * At the time of this writing, they include :
     * ZSTD_c_rsyncable
     * ZSTD_c_format
     * ZSTD_c_forceMaxWindow
     * ZSTD_c_forceAttachDict
     * ZSTD_c_literalCompressionMode
     * ZSTD_c_targetCBlockSize
     * Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them.
     * note : never ever use experimentalParam? names directly;
     *        also, the enums values themselves are unstable and can still change.
     */
     ZSTD_c_experimentalParam1=500,
     ZSTD_c_experimentalParam2=10,
     ZSTD_c_experimentalParam3=1000,
     ZSTD_c_experimentalParam4=1001,
     ZSTD_c_experimentalParam5=1002,
     ZSTD_c_experimentalParam6=1003,
} ZSTD_cParameter;
</b></pre><BR>
<pre><b>typedef struct {
    size_t error;
    int lowerBound;
    int upperBound;
} ZSTD_bounds;
</b></pre><BR>
<pre><b>ZSTD_bounds ZSTD_cParam_getBounds(ZSTD_cParameter cParam);
</b><p>  All parameters must belong to an interval with lower and upper bounds,
  otherwise they will either trigger an error or be automatically clamped.
 @return : a structure, ZSTD_bounds, which contains
         - an error status field, which must be tested using ZSTD_isError()
         - lower and upper bounds, both inclusive
 
</p></pre><BR>

<pre><b>size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int value);
</b><p>  Set one compression parameter, selected by enum ZSTD_cParameter.
  All parameters have valid bounds. Bounds can be queried using ZSTD_cParam_getBounds().
  Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter).
  Setting a parameter is generally only possible during frame initialization (before starting compression).
  Exception : when using multi-threading mode (nbWorkers >= 1),
              the following parameters can be updated _during_ compression (within same frame):
              => compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy.
              new parameters will be active for next job only (after a flush()).
 @return : an error code (which can be tested using ZSTD_isError()).