112 lines
4.8 KiB
C
112 lines
4.8 KiB
C
/**
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* Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*/
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#ifndef DICTBUILDER_H_001
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#define DICTBUILDER_H_001
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#if defined (__cplusplus)
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extern "C" {
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#endif
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/*====== Dependencies ======*/
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#include <stddef.h> /* size_t */
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/*====== Export for Windows ======*/
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/*!
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* ZSTD_DLL_EXPORT :
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* Enable exporting of functions when building a Windows DLL
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*/
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#if defined(_WIN32) && defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
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# define ZDICTLIB_API __declspec(dllexport)
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#else
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# define ZDICTLIB_API
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#endif
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/*! ZDICT_trainFromBuffer() :
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Train a dictionary from an array of samples.
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Samples must be stored concatenated in a single flat buffer `samplesBuffer`,
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supplied with an array of sizes `samplesSizes`, providing the size of each sample, in order.
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The resulting dictionary will be saved into `dictBuffer`.
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@return : size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)
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or an error code, which can be tested with ZDICT_isError().
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Tips : In general, a reasonable dictionary has a size of ~ 100 KB.
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It's obviously possible to target smaller or larger ones, just by specifying different `dictBufferCapacity`.
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In general, it's recommended to provide a few thousands samples, but this can vary a lot.
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It's recommended that total size of all samples be about ~x100 times the target size of dictionary.
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*/
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ZDICTLIB_API size_t ZDICT_trainFromBuffer(void* dictBuffer, size_t dictBufferCapacity,
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const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples);
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/*====== Helper functions ======*/
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ZDICTLIB_API unsigned ZDICT_getDictID(const void* dictBuffer, size_t dictSize); /**< extracts dictID; @return zero if error (not a valid dictionary) */
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ZDICTLIB_API unsigned ZDICT_isError(size_t errorCode);
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ZDICTLIB_API const char* ZDICT_getErrorName(size_t errorCode);
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#ifdef ZDICT_STATIC_LINKING_ONLY
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/* ====================================================================================
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* The definitions in this section are considered experimental.
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* They should never be used with a dynamic library, as they may change in the future.
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* They are provided for advanced usages.
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* Use them only in association with static linking.
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* ==================================================================================== */
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typedef struct {
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unsigned selectivityLevel; /* 0 means default; larger => select more => larger dictionary */
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int compressionLevel; /* 0 means default; target a specific zstd compression level */
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unsigned notificationLevel; /* Write to stderr; 0 = none (default); 1 = errors; 2 = progression; 3 = details; 4 = debug; */
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unsigned dictID; /* 0 means auto mode (32-bits random value); other : force dictID value */
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unsigned reserved[2]; /* reserved space for future parameters */
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} ZDICT_params_t;
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/*! ZDICT_trainFromBuffer_advanced() :
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Same as ZDICT_trainFromBuffer() with control over more parameters.
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`parameters` is optional and can be provided with values set to 0 to mean "default".
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@return : size of dictionary stored into `dictBuffer` (<= `dictBufferSize`),
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or an error code, which can be tested by ZDICT_isError().
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note : ZDICT_trainFromBuffer_advanced() will send notifications into stderr if instructed to, using notificationLevel>0.
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*/
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size_t ZDICT_trainFromBuffer_advanced(void* dictBuffer, size_t dictBufferCapacity,
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const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples,
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ZDICT_params_t parameters);
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/*! ZDICT_addEntropyTablesFromBuffer() :
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Given a content-only dictionary (built using any 3rd party algorithm),
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add entropy tables computed from an array of samples.
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Samples must be stored concatenated in a flat buffer `samplesBuffer`,
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supplied with an array of sizes `samplesSizes`, providing the size of each sample in order.
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The input dictionary content must be stored *at the end* of `dictBuffer`.
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Its size is `dictContentSize`.
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The resulting dictionary with added entropy tables will be *written back to `dictBuffer`*,
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starting from its beginning.
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@return : size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`).
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*/
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size_t ZDICT_addEntropyTablesFromBuffer(void* dictBuffer, size_t dictContentSize, size_t dictBufferCapacity,
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const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples);
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#endif /* ZDICT_STATIC_LINKING_ONLY */
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#if defined (__cplusplus)
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}
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#endif
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#endif /* DICTBUILDER_H_001 */
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