ce188d4d |
1 | /* libFLAC - Free Lossless Audio Codec library |
2 | * Copyright (C) 2004-2009 Josh Coalson |
3 | * Copyright (C) 2011-2016 Xiph.Org Foundation |
4 | * |
5 | * Redistribution and use in source and binary forms, with or without |
6 | * modification, are permitted provided that the following conditions |
7 | * are met: |
8 | * |
9 | * - Redistributions of source code must retain the above copyright |
10 | * notice, this list of conditions and the following disclaimer. |
11 | * |
12 | * - Redistributions in binary form must reproduce the above copyright |
13 | * notice, this list of conditions and the following disclaimer in the |
14 | * documentation and/or other materials provided with the distribution. |
15 | * |
16 | * - Neither the name of the Xiph.org Foundation nor the names of its |
17 | * contributors may be used to endorse or promote products derived from |
18 | * this software without specific prior written permission. |
19 | * |
20 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
21 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
22 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
23 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR |
24 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
25 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
26 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
27 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
28 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
29 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
30 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
31 | */ |
32 | |
33 | #ifndef FLAC__CALLBACK_H |
34 | #define FLAC__CALLBACK_H |
35 | |
36 | #include "ordinals.h" |
37 | #include <stdlib.h> /* for size_t */ |
38 | |
39 | /** \file include/FLAC/callback.h |
40 | * |
41 | * \brief |
42 | * This module defines the structures for describing I/O callbacks |
43 | * to the other FLAC interfaces. |
44 | * |
45 | * See the detailed documentation for callbacks in the |
46 | * \link flac_callbacks callbacks \endlink module. |
47 | */ |
48 | |
49 | /** \defgroup flac_callbacks FLAC/callback.h: I/O callback structures |
50 | * \ingroup flac |
51 | * |
52 | * \brief |
53 | * This module defines the structures for describing I/O callbacks |
54 | * to the other FLAC interfaces. |
55 | * |
56 | * The purpose of the I/O callback functions is to create a common way |
57 | * for the metadata interfaces to handle I/O. |
58 | * |
59 | * Originally the metadata interfaces required filenames as the way of |
60 | * specifying FLAC files to operate on. This is problematic in some |
61 | * environments so there is an additional option to specify a set of |
62 | * callbacks for doing I/O on the FLAC file, instead of the filename. |
63 | * |
64 | * In addition to the callbacks, a FLAC__IOHandle type is defined as an |
65 | * opaque structure for a data source. |
66 | * |
67 | * The callback function prototypes are similar (but not identical) to the |
68 | * stdio functions fread, fwrite, fseek, ftell, feof, and fclose. If you use |
69 | * stdio streams to implement the callbacks, you can pass fread, fwrite, and |
70 | * fclose anywhere a FLAC__IOCallback_Read, FLAC__IOCallback_Write, or |
71 | * FLAC__IOCallback_Close is required, and a FILE* anywhere a FLAC__IOHandle |
72 | * is required. \warning You generally CANNOT directly use fseek or ftell |
73 | * for FLAC__IOCallback_Seek or FLAC__IOCallback_Tell since on most systems |
74 | * these use 32-bit offsets and FLAC requires 64-bit offsets to deal with |
75 | * large files. You will have to find an equivalent function (e.g. ftello), |
76 | * or write a wrapper. The same is true for feof() since this is usually |
77 | * implemented as a macro, not as a function whose address can be taken. |
78 | * |
79 | * \{ |
80 | */ |
81 | |
82 | #ifdef __cplusplus |
83 | extern "C" { |
84 | #endif |
85 | |
86 | /** This is the opaque handle type used by the callbacks. Typically |
87 | * this is a \c FILE* or address of a file descriptor. |
88 | */ |
89 | typedef void* FLAC__IOHandle; |
90 | |
91 | /** Signature for the read callback. |
92 | * The signature and semantics match POSIX fread() implementations |
93 | * and can generally be used interchangeably. |
94 | * |
95 | * \param ptr The address of the read buffer. |
96 | * \param size The size of the records to be read. |
97 | * \param nmemb The number of records to be read. |
98 | * \param handle The handle to the data source. |
99 | * \retval size_t |
100 | * The number of records read. |
101 | */ |
102 | typedef size_t (*FLAC__IOCallback_Read) (void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle); |
103 | |
104 | /** Signature for the write callback. |
105 | * The signature and semantics match POSIX fwrite() implementations |
106 | * and can generally be used interchangeably. |
107 | * |
108 | * \param ptr The address of the write buffer. |
109 | * \param size The size of the records to be written. |
110 | * \param nmemb The number of records to be written. |
111 | * \param handle The handle to the data source. |
112 | * \retval size_t |
113 | * The number of records written. |
114 | */ |
115 | typedef size_t (*FLAC__IOCallback_Write) (const void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle); |
116 | |
117 | /** Signature for the seek callback. |
118 | * The signature and semantics mostly match POSIX fseek() WITH ONE IMPORTANT |
119 | * EXCEPTION: the offset is a 64-bit type whereas fseek() is generally 'long' |
120 | * and 32-bits wide. |
121 | * |
122 | * \param handle The handle to the data source. |
123 | * \param offset The new position, relative to \a whence |
124 | * \param whence \c SEEK_SET, \c SEEK_CUR, or \c SEEK_END |
125 | * \retval int |
126 | * \c 0 on success, \c -1 on error. |
127 | */ |
128 | typedef int (*FLAC__IOCallback_Seek) (FLAC__IOHandle handle, FLAC__int64 offset, int whence); |
129 | |
130 | /** Signature for the tell callback. |
131 | * The signature and semantics mostly match POSIX ftell() WITH ONE IMPORTANT |
132 | * EXCEPTION: the offset is a 64-bit type whereas ftell() is generally 'long' |
133 | * and 32-bits wide. |
134 | * |
135 | * \param handle The handle to the data source. |
136 | * \retval FLAC__int64 |
137 | * The current position on success, \c -1 on error. |
138 | */ |
139 | typedef FLAC__int64 (*FLAC__IOCallback_Tell) (FLAC__IOHandle handle); |
140 | |
141 | /** Signature for the EOF callback. |
142 | * The signature and semantics mostly match POSIX feof() but WATCHOUT: |
143 | * on many systems, feof() is a macro, so in this case a wrapper function |
144 | * must be provided instead. |
145 | * |
146 | * \param handle The handle to the data source. |
147 | * \retval int |
148 | * \c 0 if not at end of file, nonzero if at end of file. |
149 | */ |
150 | typedef int (*FLAC__IOCallback_Eof) (FLAC__IOHandle handle); |
151 | |
152 | /** Signature for the close callback. |
153 | * The signature and semantics match POSIX fclose() implementations |
154 | * and can generally be used interchangeably. |
155 | * |
156 | * \param handle The handle to the data source. |
157 | * \retval int |
158 | * \c 0 on success, \c EOF on error. |
159 | */ |
160 | typedef int (*FLAC__IOCallback_Close) (FLAC__IOHandle handle); |
161 | |
162 | /** A structure for holding a set of callbacks. |
163 | * Each FLAC interface that requires a FLAC__IOCallbacks structure will |
164 | * describe which of the callbacks are required. The ones that are not |
165 | * required may be set to NULL. |
166 | * |
167 | * If the seek requirement for an interface is optional, you can signify that |
168 | * a data sorce is not seekable by setting the \a seek field to \c NULL. |
169 | */ |
170 | typedef struct { |
171 | FLAC__IOCallback_Read read; |
172 | FLAC__IOCallback_Write write; |
173 | FLAC__IOCallback_Seek seek; |
174 | FLAC__IOCallback_Tell tell; |
175 | FLAC__IOCallback_Eof eof; |
176 | FLAC__IOCallback_Close close; |
177 | } FLAC__IOCallbacks; |
178 | |
179 | /* \} */ |
180 | |
181 | #ifdef __cplusplus |
182 | } |
183 | #endif |
184 | |
185 | #endif |