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| 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 |
| 82 extern "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 */ |
| 88 typedef 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 */ |
| 101 typedef size_t (*FLAC__IOCallback_Read) (void *ptr, size_t size, size_t nmemb, F
LAC__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 */ |
| 114 typedef size_t (*FLAC__IOCallback_Write) (const void *ptr, size_t size, size_t n
memb, 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 */ |
| 127 typedef 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 */ |
| 138 typedef 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 */ |
| 149 typedef 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 */ |
| 159 typedef 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 */ |
| 169 typedef 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 |
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