1/* libFLAC - Free Lossless Audio Codec library 2 * Copyright (C) 2004,2005,2006,2007 Josh Coalson 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * - Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 11 * - Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * - Neither the name of the Xiph.org Foundation nor the names of its 16 * contributors may be used to endorse or promote products derived from 17 * this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR 23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32#ifndef FLAC__CALLBACK_H 33#define FLAC__CALLBACK_H 34 35#include "ordinals.h" 36#include <stdlib.h> /* for size_t */ 37 38/** \file include/FLAC/callback.h 39 * 40 * \brief 41 * This module defines the structures for describing I/O callbacks 42 * to the other FLAC interfaces. 43 * 44 * See the detailed documentation for callbacks in the 45 * \link flac_callbacks callbacks \endlink module. 46 */ 47 48/** \defgroup flac_callbacks FLAC/callback.h: I/O callback structures 49 * \ingroup flac 50 * 51 * \brief 52 * This module defines the structures for describing I/O callbacks 53 * to the other FLAC interfaces. 54 * 55 * The purpose of the I/O callback functions is to create a common way 56 * for the metadata interfaces to handle I/O. 57 * 58 * Originally the metadata interfaces required filenames as the way of 59 * specifying FLAC files to operate on. This is problematic in some 60 * environments so there is an additional option to specify a set of 61 * callbacks for doing I/O on the FLAC file, instead of the filename. 62 * 63 * In addition to the callbacks, a FLAC__IOHandle type is defined as an 64 * opaque structure for a data source. 65 * 66 * The callback function prototypes are similar (but not identical) to the 67 * stdio functions fread, fwrite, fseek, ftell, feof, and fclose. If you use 68 * stdio streams to implement the callbacks, you can pass fread, fwrite, and 69 * fclose anywhere a FLAC__IOCallback_Read, FLAC__IOCallback_Write, or 70 * FLAC__IOCallback_Close is required, and a FILE* anywhere a FLAC__IOHandle 71 * is required. \warning You generally CANNOT directly use fseek or ftell 72 * for FLAC__IOCallback_Seek or FLAC__IOCallback_Tell since on most systems 73 * these use 32-bit offsets and FLAC requires 64-bit offsets to deal with 74 * large files. You will have to find an equivalent function (e.g. ftello), 75 * or write a wrapper. The same is true for feof() since this is usually 76 * implemented as a macro, not as a function whose address can be taken. 77 * 78 * \{ 79 */ 80 81#ifdef __cplusplus 82extern "C" { 83#endif 84 85/** This is the opaque handle type used by the callbacks. Typically 86 * this is a \c FILE* or address of a file descriptor. 87 */ 88typedef void* FLAC__IOHandle; 89 90/** Signature for the read callback. 91 * The signature and semantics match POSIX fread() implementations 92 * and can generally be used interchangeably. 93 * 94 * \param ptr The address of the read buffer. 95 * \param size The size of the records to be read. 96 * \param nmemb The number of records to be read. 97 * \param handle The handle to the data source. 98 * \retval size_t 99 * The number of records read. 100 */ 101typedef size_t (*FLAC__IOCallback_Read) (void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle); 102 103/** Signature for the write callback. 104 * The signature and semantics match POSIX fwrite() implementations 105 * and can generally be used interchangeably. 106 * 107 * \param ptr The address of the write buffer. 108 * \param size The size of the records to be written. 109 * \param nmemb The number of records to be written. 110 * \param handle The handle to the data source. 111 * \retval size_t 112 * The number of records written. 113 */ 114typedef size_t (*FLAC__IOCallback_Write) (const void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle); 115 116/** Signature for the seek callback. 117 * The signature and semantics mostly match POSIX fseek() WITH ONE IMPORTANT 118 * EXCEPTION: the offset is a 64-bit type whereas fseek() is generally 'long' 119 * and 32-bits wide. 120 * 121 * \param handle The handle to the data source. 122 * \param offset The new position, relative to \a whence 123 * \param whence \c SEEK_SET, \c SEEK_CUR, or \c SEEK_END 124 * \retval int 125 * \c 0 on success, \c -1 on error. 126 */ 127typedef int (*FLAC__IOCallback_Seek) (FLAC__IOHandle handle, FLAC__int64 offset, int whence); 128 129/** Signature for the tell callback. 130 * The signature and semantics mostly match POSIX ftell() WITH ONE IMPORTANT 131 * EXCEPTION: the offset is a 64-bit type whereas ftell() is generally 'long' 132 * and 32-bits wide. 133 * 134 * \param handle The handle to the data source. 135 * \retval FLAC__int64 136 * The current position on success, \c -1 on error. 137 */ 138typedef FLAC__int64 (*FLAC__IOCallback_Tell) (FLAC__IOHandle handle); 139 140/** Signature for the EOF callback. 141 * The signature and semantics mostly match POSIX feof() but WATCHOUT: 142 * on many systems, feof() is a macro, so in this case a wrapper function 143 * must be provided instead. 144 * 145 * \param handle The handle to the data source. 146 * \retval int 147 * \c 0 if not at end of file, nonzero if at end of file. 148 */ 149typedef int (*FLAC__IOCallback_Eof) (FLAC__IOHandle handle); 150 151/** Signature for the close callback. 152 * The signature and semantics match POSIX fclose() implementations 153 * and can generally be used interchangeably. 154 * 155 * \param handle The handle to the data source. 156 * \retval int 157 * \c 0 on success, \c EOF on error. 158 */ 159typedef int (*FLAC__IOCallback_Close) (FLAC__IOHandle handle); 160 161/** A structure for holding a set of callbacks. 162 * Each FLAC interface that requires a FLAC__IOCallbacks structure will 163 * describe which of the callbacks are required. The ones that are not 164 * required may be set to NULL. 165 * 166 * If the seek requirement for an interface is optional, you can signify that 167 * a data sorce is not seekable by setting the \a seek field to \c NULL. 168 */ 169typedef struct { 170 FLAC__IOCallback_Read read; 171 FLAC__IOCallback_Write write; 172 FLAC__IOCallback_Seek seek; 173 FLAC__IOCallback_Tell tell; 174 FLAC__IOCallback_Eof eof; 175 FLAC__IOCallback_Close close; 176} FLAC__IOCallbacks; 177 178/* \} */ 179 180#ifdef __cplusplus 181} 182#endif 183 184#endif 185