zstd/lib/dictBuilder/zdict.h

/*
    dictBuilder header file
    Copyright (C) Yann Collet 2016

    BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

    * Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above
    copyright notice, this list of conditions and the following disclaimer
    in the documentation and/or other materials provided with the
    distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    You can contact the author at :
       - Zstd source repository : https://www.zstd.net
*/

#ifndef DICTBUILDER_H_001
#define DICTBUILDER_H_001

#if defined (__cplusplus)
extern "C" {
#endif

/*! ZDICT_trainFromBuffer() :
    Train a dictionary from an array of samples.
    Samples must be stored concatenated in a single flat buffer `samplesBuffer`,
    supplied with an array of sizes `samplesSizes`, providing the size of each sample, in order.
    The resulting dictionary will be saved into `dictBuffer`.
    @return : size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)
              or an error code, which can be tested with ZDICT_isError().
    Tips : In general, a reasonable dictionary has a size of ~ 100 KB.
           It's obviously possible to target smaller or larger ones, just by specifying different `dictBufferCapacity`.
           In general, it's recommended to provide a few thousands samples, but this can vary a lot.
           It's recommended that total size of all samples be about ~x100 times the target size of dictionary.
*/
size_t ZDICT_trainFromBuffer(void* dictBuffer, size_t dictBufferCapacity,
                       const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples);


/*======   Helper functions   ======*/
unsigned ZDICT_isError(size_t errorCode);
const char* ZDICT_getErrorName(size_t errorCode);



#ifdef ZDICT_STATIC_LINKING_ONLY

/* ====================================================================================
 * The definitions in this section are considered experimental.
 * They should never be used with a dynamic library, as they may change in the future.
 * They are provided for advanced usages.
 * Use them only in association with static linking.
 * ==================================================================================== */

typedef struct {
    unsigned selectivityLevel;   /* 0 means default; larger => select more => larger dictionary */
    int      compressionLevel;   /* 0 means default; target a specific zstd compression level */
    unsigned notificationLevel;  /* Write to stderr; 0 = none (default); 1 = errors; 2 = progression; 3 = details; 4 = debug; */
    unsigned dictID;             /* 0 means auto mode (32-bits random value); other : force dictID value */
    unsigned reserved[2];        /* space for future parameters */
} ZDICT_params_t;


/*! ZDICT_trainFromBuffer_advanced() :
    Same as ZDICT_trainFromBuffer() with control over more parameters.
    `parameters` is optional and can be provided with values set to 0 to mean "default".
    @return : size of dictionary stored into `dictBuffer` (<= `dictBufferSize`),
              or an error code, which can be tested by ZDICT_isError().
    note : ZDICT_trainFromBuffer_advanced() will send notifications into stderr if instructed to, using notificationLevel>0.
*/
size_t ZDICT_trainFromBuffer_advanced(void* dictBuffer, size_t dictBufferCapacity,
                                const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples,
                                ZDICT_params_t parameters);


/*! ZDICT_addEntropyTablesFromBuffer() :

    Given a content-only dictionary (built using any 3rd party algorithm),
    add entropy tables computed from an array of samples.
    Samples must be stored concatenated in a flat buffer `samplesBuffer`,
    supplied with an array of sizes `samplesSizes`, providing the size of each sample in order.

    The input dictionary content must be stored *at the end* of `dictBuffer`.
    Its size is `dictContentSize`.
    The resulting dictionary with added entropy tables will be *written back to `dictBuffer`*,
    starting from its beginning.
    @return : size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`).
*/
size_t ZDICT_addEntropyTablesFromBuffer(void* dictBuffer, size_t dictContentSize, size_t dictBufferCapacity,
                                        const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples);



#endif   /* ZDICT_STATIC_LINKING_ONLY */

#if defined (__cplusplus)
}
#endif

#endif   /* DICTBUILDER_H_001 */