113 lines
3.9 KiB
C
113 lines
3.9 KiB
C
/**********************************************************************
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* Project: CPL - Common Portability Library
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* Purpose: Registry of compression/decompression functions
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* Author: Even Rouault <even.rouault at spatialys.com>
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*
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**********************************************************************
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* Copyright (c) 2021, Even Rouault <even.rouault at spatialys.com>
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*
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* SPDX-License-Identifier: MIT
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****************************************************************************/
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#ifndef CPL_COMPRESSOR_H_INCLUDED
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#define CPL_COMPRESSOR_H_INCLUDED
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#include "cpl_port.h"
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#include <stdbool.h>
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/**
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* \file cpl_compressor.h
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*
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* API for compressors and decompressors of binary buffers.
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*/
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CPL_C_START
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/** Callback of a compressor/decompressor.
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*
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* For a compressor, input is uncompressed data, and output compressed data.
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* For a decompressor, input is compressed data, and output uncompressed data.
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*
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* Valid situations for output_data and output_size are:
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* <ul>
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* <li>output_data != NULL and *output_data != NULL and output_size != NULL and
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* *output_size != 0. The caller provides the output
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* buffer in *output_data and its size in *output_size. In case of successful
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* operation, *output_size will be updated to the actual size.
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* This mode is the one that is always guaranteed to be implemented efficiently.
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* In case of failure due to insufficient space, it will be updated to the size
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* needed (if known), or 0 (if unknown)</li>
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* <li>output_data == NULL and output_size != NULL. *output_size will be updated
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* with the minimum size the output buffer should be (if known), or 0 (if
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* unknown).</li> <li>output_data != NULL and *output_data == NULL and
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* output_size != NULL. *output_data will be allocated using VSIMalloc(), and
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* should be freed by the caller with VSIFree(). *output_size will be updated to
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* the size of the output buffer.</li>
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* </ul>
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*
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* @param input_data Input data. Should not be NULL.
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* @param input_size Size of input data, in bytes.
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* @param output_data Pointer to output data.
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* @param output_size Pointer to output size.
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* @param options NULL terminated list of options. Or NULL.
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* @param compressor_user_data User data provided at registration time.
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* @return true in case of success.
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*/
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typedef bool (*CPLCompressionFunc)(const void *input_data, size_t input_size,
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void **output_data, size_t *output_size,
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CSLConstList options,
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void *compressor_user_data);
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/** Type of compressor */
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typedef enum
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{
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/** Compressor */
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CCT_COMPRESSOR,
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/** Filter */
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CCT_FILTER
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} CPLCompressorType;
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/** Compressor/decompressor description */
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typedef struct
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{
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/** Structure version. Should be set to 1 */
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int nStructVersion;
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/** Id of the compressor/decompressor. Should NOT be NULL. */
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const char *pszId;
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/** Compressor type */
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CPLCompressorType eType;
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/** Metadata, as a NULL terminated list of strings. Or NULL.
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* The OPTIONS metadata key is reserved for compressors/decompressors to
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* provide the available options as a XML string of the form
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* <Options>
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* <Option name='' type='' description='' default=''/>
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* </Options>
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*/
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CSLConstList papszMetadata;
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/** Compressor/decompressor callback. Should NOT be NULL. */
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CPLCompressionFunc pfnFunc;
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/** User data to provide to the callback. May be NULL. */
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void *user_data;
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} CPLCompressor;
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bool CPL_DLL CPLRegisterCompressor(const CPLCompressor *compressor);
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bool CPL_DLL CPLRegisterDecompressor(const CPLCompressor *decompressor);
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char CPL_DLL **CPLGetCompressors(void);
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char CPL_DLL **CPLGetDecompressors(void);
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const CPLCompressor CPL_DLL *CPLGetCompressor(const char *pszId);
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const CPLCompressor CPL_DLL *CPLGetDecompressor(const char *pszId);
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/*! @cond Doxygen_Suppress */
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void CPL_DLL CPLDestroyCompressorRegistry(void);
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/*! @endcond */
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CPL_C_END
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#endif // CPL_COMPRESSOR_H_INCLUDED
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