text: /*
   * Copyright (c) 2016-2020, 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 DICTBUILDER_H_001
  #define DICTBUILDER_H_001
  
  #if defined (__cplusplus)
  extern "C" {
  #endif
  
  
  /*======  Dependencies  ======*/
  #include <stddef.h>  /* size_t */
  
  
  /* =====   ZDICTLIB_API : control library symbols visibility   ===== */
  #ifndef ZDICTLIB_VISIBILITY
  #  if defined(__GNUC__) && (__GNUC__ >= 4)
  #    define ZDICTLIB_VISIBILITY __attribute__ ((visibility ("default")))
  #  else
  #    define ZDICTLIB_VISIBILITY
  #  endif
  #endif
  #if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
  #  define ZDICTLIB_API __declspec(dllexport) ZDICTLIB_VISIBILITY
  #elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1)
  #  define ZDICTLIB_API __declspec(dllimport) ZDICTLIB_VISIBILITY /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/
  #else
  #  define ZDICTLIB_API ZDICTLIB_VISIBILITY
  #endif
  
  
  /*! ZDICT_trainFromBuffer():
   *  Train a dictionary from an array of samples.
   *  Redirect towards ZDICT_optimizeTrainFromBuffer_fastCover() single-threaded, with d=8, steps=4,
   *  f=20, and accel=1.
   *  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().
   *  Note:  Dictionary training will fail if there are not enough samples to construct a
   *         dictionary, or if most of the samples are too small (< 8 bytes being the lower limit).
   *         If dictionary training fails, you should use zstd without a dictionary, as the dictionary
   *         would've been ineffective anyways. If you believe your samples would benefit from a dictionary
   *         please open an issue with details, and we can look into it.
   *  Note: ZDICT_trainFromBuffer()'s memory usage is about 6 MB.
   *  Tips: In general, a reasonable dictionary has a size of ~ 100 KB.
   *        It's possible to select smaller or larger size, just by specifying `dictBufferCapacity`.
   *        In general, it's recommended to provide a few thousands samples, though this can vary a lot.
   *        It's recommended that total size of all samples be about ~x100 times the target size of dictionary.
   */
  ZDICTLIB_API size_t ZDICT_trainFromBuffer(void* dictBuffer, size_t dictBufferCapacity,
                                      const void* samplesBuffer,
                                      const size_t* samplesSizes, unsigned nbSamples);
  
  typedef struct {
      int      compressionLevel;   /*< optimize for a specific zstd compression level; 0 means default */
      unsigned notificationLevel;  /*< Write log to stderr; 0 = none (default); 1 = errors; 2 = progression; 3 = details; 4 = debug; */
      unsigned dictID;             /*< force dictID value; 0 means auto mode (32-bits random value) */
  } ZDICT_params_t;
  
  /*! ZDICT_finalizeDictionary():
   * Given a custom content as a basis for dictionary, and a set of samples,
   * finalize dictionary by adding headers and statistics according to the zstd
   * dictionary format.
   *
   * 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 samples are used to construct the statistics, so they
   * should be representative of what you will compress with this dictionary.
   *
   * The compression level can be set in `parameters`. You should pass the
   * compression level you expect to use in production. The statistics for each
   * compression level differ, so tuning the dictionary for the compression level
   * can help quite a bit.
   *
   * You can set an explicit dictionary ID in `parameters`, or allow us to pick
   * a random dictionary ID for you, but we can't guarantee no collisions.
   *
   * The dstDictBuffer and the dictContent may overlap, and the content will be
   * appended to the end of the header. If the header + the content doesn't fit in
   * maxDictSize the beginning of the content is truncated to make room, since it
   * is presumed that the most profitable content is at the end of the dictionary,
   * since that is the cheapest to reference.
   *
   * `dictContentSize` must be >= ZDICT_CONTENTSIZE_MIN bytes.
   * `maxDictSize` must be >= max(dictContentSize, ZSTD_DICTSIZE_MIN).
   *
   * @return: size of dictionary stored into `dstDictBuffer` (<= `maxDictSize`),
   *          or an error code, which can be tested by ZDICT_isError().
   * Note: ZDICT_finalizeDictionary() will push notifications into stderr if
   *       instructed to, using notificationLevel>0.
   * NOTE: This function currently may fail in several edge cases including:
   *         * Not enough samples
   *         * Samples are uncompressible
   *         * Samples are all exactly the same
   */
  ZDICTLIB_API size_t ZDICT_finalizeDictionary(void* dstDictBuffer, size_t maxDictSize,
                                  const void* dictContent, size_t dictContentSize,
                                  const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples,
                                  ZDICT_params_t parameters);
  
  
  /*======   Helper functions   ======*/
  ZDICTLIB_API unsigned ZDICT_getDictID(const void* dictBuffer, size_t dictSize);  /**< extracts dictID; @return zero if error (not a valid dictionary) */
  ZDICTLIB_API size_t ZDICT_getDictHeaderSize(const void* dictBuffer, size_t dictSize);  /* returns dict header size; returns a ZSTD error code on failure */
  ZDICTLIB_API unsigned ZDICT_isError(size_t errorCode);
  ZDICTLIB_API 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.
   * ==================================================================================== */
  
  #define ZDICT_CONTENTSIZE_MIN 128
  #define ZDICT_DICTSIZE_MIN    256
  
  /*! ZDICT_cover_params_t:
   *  k and d are the only required parameters.
   *  For others, value 0 means default.
   */
  typedef struct {
      unsigned k;                  /* Segment size : constraint: 0 < k : Reasonable range [16, 2048+] */
      unsigned d;                  /* dmer size : constraint: 0 < d <= k : Reasonable range [6, 16] */
      unsigned steps;              /* Number of steps : Only used for optimization : 0 means default (40) : Higher means more parameters checked */
      unsigned nbThreads;          /* Number of threads : constraint: 0 < nbThreads : 1 means single-threaded : Only used for optimization : Ignored if ZSTD_MULTITHREAD is not defined */
      double splitPoint;           /* Percentage of samples used for training: Only used for optimization : the first nbSamples * splitPoint samples will be used to training, the last nbSamples * (1 - splitPoint) samples will be used for testing, 0 means default (1.0), 1.0 when all samples are used for both training and testing */
      unsigned shrinkDict;         /* Train dictionaries to shrink in size starting from the minimum size and selects the smallest dictionary that is shrinkDictMaxRegression% worse than the largest dictionary. 0 means no shrinking and 1 means shrinking  */
      unsigned shrinkDictMaxRegression; /* Sets shrinkDictMaxRegression so that a smaller dictionary can be at worse shrinkDictMaxRegression% worse than the max dict size dictionary. */
      ZDICT_params_t zParams;
  } ZDICT_cover_params_t;
  
  typedef struct {
      unsigned k;                  /* Segment size : constraint: 0 < k : Reasonable range [16, 2048+] */
      unsigned d;                  /* dmer size : constraint: 0 < d <= k : Reasonable range [6, 16] */
      unsigned f;                  /* log of size of frequency array : constraint: 0 < f <= 31 : 1 means default(20)*/
      unsigned steps;              /* Number of steps : Only used for optimization : 0 means default (40) : Higher means more parameters checked */
      unsigned nbThreads;          /* Number of threads : constraint: 0 < nbThreads : 1 means single-threaded : Only used for optimization : Ignored if ZSTD_MULTITHREAD is not defined */
      double splitPoint;           /* Percentage of samples used for training: Only used for optimization : the first nbSamples * splitPoint samples will be used to training, the last nbSamples * (1 - splitPoint) samples will be used for testing, 0 means default (0.75), 1.0 when all samples are used for both training and testing */
      unsigned accel;              /* Acceleration level: constraint: 0 < accel <= 10, higher means faster and less accurate, 0 means default(1) */
      unsigned shrinkDict;         /* Train dictionaries to shrink in size starting from the minimum size and selects the smallest dictionary that is shrinkDictMaxRegression% worse than the largest dictionary. 0 means no shrinking and 1 means shrinking  */
      unsigned shrinkDictMaxRegression; /* Sets shrinkDictMaxRegression so that a smaller dictionary can be at worse shrinkDictMaxRegression% worse than the max dict size dictionary. */
  
      ZDICT_params_t zParams;
  } ZDICT_fastCover_params_t;
  
  /*! ZDICT_trainFromBuffer_cover():
   *  Train a dictionary from an array of samples using the COVER algorithm.
   *  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().
   *          See ZDICT_trainFromBuffer() for details on failure modes.
   *  Note: ZDICT_trainFromBuffer_cover() requires about 9 bytes of memory for each input byte.
   *  Tips: In general, a reasonable dictionary has a size of ~ 100 KB.
   *        It's possible to select smaller or larger size, just by specifying `dictBufferCapacity`.
   *        In general, it's recommended to provide a few thousands samples, though this can vary a lot.
   *        It's recommended that total size of all samples be about ~x100 times the target size of dictionary.
   */
  ZDICTLIB_API size_t ZDICT_trainFromBuffer_cover(
            void *dictBuffer, size_t dictBufferCapacity,
      const void *samplesBuffer, const size_t *samplesSizes, unsigned nbSamples,
            ZDICT_cover_params_t parameters);
  
  /*! ZDICT_optimizeTrainFromBuffer_cover():
   * The same requirements as above hold for all the parameters except `parameters`.
   * This function tries many parameter combinations and picks the best parameters.
   * `*parameters` is filled with the best parameters found,
   * dictionary constructed with those parameters is stored in `dictBuffer`.
   *
   * All of the parameters d, k, steps are optional.
   * If d is non-zero then we don't check multiple values of d, otherwise we check d = {6, 8}.
   * if steps is zero it defaults to its default value.
   * If k is non-zero then we don't check multiple values of k, otherwise we check steps values in [50, 2000].
   *
   * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)
   *          or an error code, which can be tested with ZDICT_isError().
   *          On success `*parameters` contains the parameters selected.
   *          See ZDICT_trainFromBuffer() for details on failure modes.
   * Note: ZDICT_optimizeTrainFromBuffer_cover() requires about 8 bytes of memory for each input byte and additionally another 5 bytes of memory for each byte of memory for each thread.
   */
  ZDICTLIB_API size_t ZDICT_optimizeTrainFromBuffer_cover(
            void* dictBuffer, size_t dictBufferCapacity,
      const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples,
            ZDICT_cover_params_t* parameters);
  
  /*! ZDICT_trainFromBuffer_fastCover():
   *  Train a dictionary from an array of samples using a modified version of COVER algorithm.
   *  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.
   *  d and k are required.
   *  All other parameters are optional, will use default values if not provided
   *  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().
   *          See ZDICT_trainFromBuffer() for details on failure modes.
   *  Note: ZDICT_trainFromBuffer_fastCover() requires 6 * 2^f bytes of memory.
   *  Tips: In general, a reasonable dictionary has a size of ~ 100 KB.
   *        It's possible to select smaller or larger size, just by specifying `dictBufferCapacity`.
   *        In general, it's recommended to provide a few thousands samples, though this can vary a lot.
   *        It's recommended that total size of all samples be about ~x100 times the target size of dictionary.
   */
  ZDICTLIB_API size_t ZDICT_trainFromBuffer_fastCover(void *dictBuffer,
                      size_t dictBufferCapacity, const void *samplesBuffer,
                      const size_t *samplesSizes, unsigned nbSamples,
                      ZDICT_fastCover_params_t parameters);
  
  /*! ZDICT_optimizeTrainFromBuffer_fastCover():
   * The same requirements as above hold for all the parameters except `parameters`.
   * This function tries many parameter combinations (specifically, k and d combinations)
   * and picks the best parameters. `*parameters` is filled with the best parameters found,
   * dictionary constructed with those parameters is stored in `dictBuffer`.
   * All of the parameters d, k, steps, f, and accel are optional.
   * If d is non-zero then we don't check multiple values of d, otherwise we check d = {6, 8}.
   * if steps is zero it defaults to its default value.
   * If k is non-zero then we don't check multiple values of k, otherwise we check steps values in [50, 2000].
   * If f is zero, default value of 20 is used.
   * If accel is zero, default value of 1 is used.
   *
   * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)
   *          or an error code, which can be tested with ZDICT_isError().
   *          On success `*parameters` contains the parameters selected.
   *          See ZDICT_trainFromBuffer() for details on failure modes.
   * Note: ZDICT_optimizeTrainFromBuffer_fastCover() requires about 6 * 2^f bytes of memory for each thread.
   */
  ZDICTLIB_API size_t ZDICT_optimizeTrainFromBuffer_fastCover(void* dictBuffer,
                      size_t dictBufferCapacity, const void* samplesBuffer,
                      const size_t* samplesSizes, unsigned nbSamples,
                      ZDICT_fastCover_params_t* parameters);
  
  typedef struct {
      unsigned selectivityLevel;   /* 0 means default; larger => select more => larger dictionary */
      ZDICT_params_t zParams;
  } ZDICT_legacy_params_t;
  
  /*! ZDICT_trainFromBuffer_legacy():
   *  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`.
   * `parameters` is optional and can be provided with values set to 0 to mean "default".
   * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)
   *          or an error code, which can be tested with ZDICT_isError().
   *          See ZDICT_trainFromBuffer() for details on failure modes.
   *  Tips: In general, a reasonable dictionary has a size of ~ 100 KB.
   *        It's possible to select smaller or larger size, just by specifying `dictBufferCapacity`.
   *        In general, it's recommended to provide a few thousands samples, though this can vary a lot.
   *        It's recommended that total size of all samples be about ~x100 times the target size of dictionary.
   *  Note: ZDICT_trainFromBuffer_legacy() will send notifications into stderr if instructed to, using notificationLevel>0.
   */
  ZDICTLIB_API size_t ZDICT_trainFromBuffer_legacy(
      void *dictBuffer, size_t dictBufferCapacity,
      const void *samplesBuffer, const size_t *samplesSizes, unsigned nbSamples,
      ZDICT_legacy_params_t parameters);
  
  /* Deprecation warnings */
  /* It is generally possible to disable deprecation warnings from compiler,
     for example with -Wno-deprecated-declarations for gcc
     or _CRT_SECURE_NO_WARNINGS in Visual.
     Otherwise, it's also possible to manually define ZDICT_DISABLE_DEPRECATE_WARNINGS */
  #ifdef ZDICT_DISABLE_DEPRECATE_WARNINGS
  #  define ZDICT_DEPRECATED(message) ZDICTLIB_API   /* disable deprecation warnings */
  #else
  #  define ZDICT_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
  #  if defined (__cplusplus) && (__cplusplus >= 201402) /* C++14 or greater */
  #    define ZDICT_DEPRECATED(message) [[deprecated(message)]] ZDICTLIB_API
  #  elif defined(__clang__) || (ZDICT_GCC_VERSION >= 405)
  #    define ZDICT_DEPRECATED(message) ZDICTLIB_API __attribute__((deprecated(message)))
  #  elif (ZDICT_GCC_VERSION >= 301)
  #    define ZDICT_DEPRECATED(message) ZDICTLIB_API __attribute__((deprecated))
  #  elif defined(_MSC_VER)
  #    define ZDICT_DEPRECATED(message) ZDICTLIB_API __declspec(deprecated(message))
  #  else
  #    pragma message("WARNING: You need to implement ZDICT_DEPRECATED for this compiler")
  #    define ZDICT_DEPRECATED(message) ZDICTLIB_API
  #  endif
  #endif /* ZDICT_DISABLE_DEPRECATE_WARNINGS */
  
  ZDICT_DEPRECATED("use ZDICT_finalizeDictionary() instead")
  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 */
  