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| -rw-r--r-- | include/FLAC/callback.h | 190 |
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diff --git a/include/FLAC/callback.h b/include/FLAC/callback.h new file mode 100644 index 0000000..4babcd3 --- /dev/null +++ b/include/FLAC/callback.h @@ -0,0 +1,190 @@ +/* libFLAC - Free Lossless Audio Codec library + * Copyright (C) 2004-2009 Josh Coalson + * Copyright (C) 2011-2023 Xiph.Org Foundation + * + * 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. + * + * - Neither the name of the Xiph.org Foundation nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * 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 FOUNDATION OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef FLAC__CALLBACK_H +#define FLAC__CALLBACK_H + +#include "ordinals.h" +#include <stdlib.h> /* for size_t */ + +/** \file include/FLAC/callback.h + * + * \brief + * This module defines the structures for describing I/O callbacks + * to the other FLAC interfaces. + * + * See the detailed documentation for callbacks in the + * \link flac_callbacks callbacks \endlink module. + */ + +/** \defgroup flac_callbacks FLAC/callback.h: I/O callback structures + * \ingroup flac + * + * \brief + * This module defines the structures for describing I/O callbacks + * to the other FLAC interfaces. + * + * The purpose of the I/O callback functions is to create a common way + * for the metadata interfaces to handle I/O. + * + * Originally the metadata interfaces required filenames as the way of + * specifying FLAC files to operate on. This is problematic in some + * environments so there is an additional option to specify a set of + * callbacks for doing I/O on the FLAC file, instead of the filename. + * + * In addition to the callbacks, a FLAC__IOHandle type is defined as an + * opaque structure for a data source. + * + * The callback function prototypes are similar (but not identical) to the + * stdio functions fread, fwrite, fseek, ftell, feof, and fclose. If you use + * stdio streams to implement the callbacks, you can pass fread, fwrite, and + * fclose anywhere a FLAC__IOCallback_Read, FLAC__IOCallback_Write, or + * FLAC__IOCallback_Close is required, and a FILE* anywhere a FLAC__IOHandle + * is required. \warning You generally CANNOT directly use fseek or ftell + * for FLAC__IOCallback_Seek or FLAC__IOCallback_Tell since on most systems + * these use 32-bit offsets and FLAC requires 64-bit offsets to deal with + * large files. You will have to find an equivalent function (e.g. ftello), + * or write a wrapper. The same is true for feof() since this is usually + * implemented as a macro, not as a function whose address can be taken. + * + * \{ + */ + +#ifdef __cplusplus +extern "C" { +#endif + +/** This is the opaque handle type used by the callbacks. Typically + * this is a \c FILE* or address of a file descriptor. + */ +typedef void* FLAC__IOHandle; + +/** Signature for the read callback. + * The signature and semantics match POSIX fread() implementations + * and can generally be used interchangeably. Note that the global + * variable errno from errno.h is read by some libFLAC functions to + * detect read errors. + * + * \param ptr The address of the read buffer. + * \param size The size of the records to be read. + * \param nmemb The number of records to be read. + * \param handle The handle to the data source. + * \retval size_t + * The number of records read. + */ +typedef size_t (*FLAC__IOCallback_Read) (void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle); + +/** Signature for the write callback. + * The signature and semantics match POSIX fwrite() implementations + * and can generally be used interchangeably. + * + * \param ptr The address of the write buffer. + * \param size The size of the records to be written. + * \param nmemb The number of records to be written. + * \param handle The handle to the data source. + * \retval size_t + * The number of records written. + */ +typedef size_t (*FLAC__IOCallback_Write) (const void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle); + +/** Signature for the seek callback. + * The signature and semantics mostly match POSIX fseek() WITH ONE IMPORTANT + * EXCEPTION: the offset is a 64-bit type whereas fseek() is generally 'long' + * and 32-bits wide. + * + * \param handle The handle to the data source. + * \param offset The new position, relative to \a whence + * \param whence \c SEEK_SET, \c SEEK_CUR, or \c SEEK_END + * \retval int + * \c 0 on success, \c -1 on error. + */ +typedef int (*FLAC__IOCallback_Seek) (FLAC__IOHandle handle, FLAC__int64 offset, int whence); + +/** Signature for the tell callback. + * The signature and semantics mostly match POSIX ftell() WITH ONE IMPORTANT + * EXCEPTION: the offset is a 64-bit type whereas ftell() is generally 'long' + * and 32-bits wide. + * + * \param handle The handle to the data source. + * \retval FLAC__int64 + * The current position on success, \c -1 on error. + */ +typedef FLAC__int64 (*FLAC__IOCallback_Tell) (FLAC__IOHandle handle); + +/** Signature for the EOF callback. + * The signature and semantics mostly match POSIX feof() but WATCHOUT: + * on many systems, feof() is a macro, so in this case a wrapper function + * must be provided instead. + * + * \param handle The handle to the data source. + * \retval int + * \c 0 if not at end of file, nonzero if at end of file. + */ +typedef int (*FLAC__IOCallback_Eof) (FLAC__IOHandle handle); + +/** Signature for the close callback. + * The signature and semantics match POSIX fclose() implementations + * and can generally be used interchangeably. + * + * \param handle The handle to the data source. + * \retval int + * \c 0 on success, \c EOF on error. + */ +typedef int (*FLAC__IOCallback_Close) (FLAC__IOHandle handle); + +/** A structure for holding a set of callbacks. + * Each FLAC interface that requires a FLAC__IOCallbacks structure will + * describe which of the callbacks are required. The ones that are not + * required may be set to NULL. + * + * If the seek requirement for an interface is optional, you can signify that + * a data source is not seekable by setting the \a seek field to \c NULL. + * + * See the detailed documentation for callbacks in the + * \link flac_callbacks callbacks \endlink module. + */ +typedef struct { + FLAC__IOCallback_Read read; /**< See FLAC__IOCallbacks */ + FLAC__IOCallback_Write write; /**< See FLAC__IOCallbacks */ + FLAC__IOCallback_Seek seek; /**< See FLAC__IOCallbacks */ + FLAC__IOCallback_Tell tell; /**< See FLAC__IOCallbacks */ + FLAC__IOCallback_Eof eof; /**< See FLAC__IOCallbacks */ + FLAC__IOCallback_Close close; /**< See FLAC__IOCallbacks */ +} FLAC__IOCallbacks; + +/* \} */ + +#ifdef __cplusplus +} +#endif + +#endif |