FFmpeg 7.1.1
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fifo.h
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1/*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19/**
20 * @file
21 * @ingroup lavu_fifo
22 * A generic FIFO API
23 */
24
25#ifndef AVUTIL_FIFO_H
26#define AVUTIL_FIFO_H
27
28#include <stddef.h>
29
30/**
31 * @defgroup lavu_fifo AVFifo
32 * @ingroup lavu_data
33 *
34 * @{
35 * A generic FIFO API
36 */
37
38typedef struct AVFifo AVFifo;
39
40/**
41 * Callback for writing or reading from a FIFO, passed to (and invoked from) the
42 * av_fifo_*_cb() functions. It may be invoked multiple times from a single
43 * av_fifo_*_cb() call and may process less data than the maximum size indicated
44 * by nb_elems.
45 *
46 * @param opaque the opaque pointer provided to the av_fifo_*_cb() function
47 * @param buf the buffer for reading or writing the data, depending on which
48 * av_fifo_*_cb function is called
49 * @param nb_elems On entry contains the maximum number of elements that can be
50 * read from / written into buf. On success, the callback should
51 * update it to contain the number of elements actually written.
52 *
53 * @return 0 on success, a negative error code on failure (will be returned from
54 * the invoking av_fifo_*_cb() function)
55 */
56typedef int AVFifoCB(void *opaque, void *buf, size_t *nb_elems);
57
58/**
59 * Automatically resize the FIFO on writes, so that the data fits. This
60 * automatic resizing happens up to a limit that can be modified with
61 * av_fifo_auto_grow_limit().
62 */
63#define AV_FIFO_FLAG_AUTO_GROW (1 << 0)
64
65/**
66 * Allocate and initialize an AVFifo with a given element size.
67 *
68 * @param elems initial number of elements that can be stored in the FIFO
69 * @param elem_size Size in bytes of a single element. Further operations on
70 * the returned FIFO will implicitly use this element size.
71 * @param flags a combination of AV_FIFO_FLAG_*
72 *
73 * @return newly-allocated AVFifo on success, a negative error code on failure
74 */
75AVFifo *av_fifo_alloc2(size_t elems, size_t elem_size,
76 unsigned int flags);
77
78/**
79 * @return Element size for FIFO operations. This element size is set at
80 * FIFO allocation and remains constant during its lifetime
81 */
82size_t av_fifo_elem_size(const AVFifo *f);
83
84/**
85 * Set the maximum size (in elements) to which the FIFO can be resized
86 * automatically. Has no effect unless AV_FIFO_FLAG_AUTO_GROW is used.
87 */
88void av_fifo_auto_grow_limit(AVFifo *f, size_t max_elems);
89
90/**
91 * @return number of elements available for reading from the given FIFO.
92 */
93size_t av_fifo_can_read(const AVFifo *f);
94
95/**
96 * @return Number of elements that can be written into the given FIFO without
97 * growing it.
98 *
99 * In other words, this number of elements or less is guaranteed to fit
100 * into the FIFO. More data may be written when the
101 * AV_FIFO_FLAG_AUTO_GROW flag was specified at FIFO creation, but this
102 * may involve memory allocation, which can fail.
103 */
104size_t av_fifo_can_write(const AVFifo *f);
105
106/**
107 * Enlarge an AVFifo.
108 *
109 * On success, the FIFO will be large enough to hold exactly
110 * inc + av_fifo_can_read() + av_fifo_can_write()
111 * elements. In case of failure, the old FIFO is kept unchanged.
112 *
113 * @param f AVFifo to resize
114 * @param inc number of elements to allocate for, in addition to the current
115 * allocated size
116 * @return a non-negative number on success, a negative error code on failure
117 */
118int av_fifo_grow2(AVFifo *f, size_t inc);
119
120/**
121 * Write data into a FIFO.
122 *
123 * In case nb_elems > av_fifo_can_write(f) and the AV_FIFO_FLAG_AUTO_GROW flag
124 * was not specified at FIFO creation, nothing is written and an error
125 * is returned.
126 *
127 * Calling function is guaranteed to succeed if nb_elems <= av_fifo_can_write(f).
128 *
129 * @param f the FIFO buffer
130 * @param buf Data to be written. nb_elems * av_fifo_elem_size(f) bytes will be
131 * read from buf on success.
132 * @param nb_elems number of elements to write into FIFO
133 *
134 * @return a non-negative number on success, a negative error code on failure
135 */
136int av_fifo_write(AVFifo *f, const void *buf, size_t nb_elems);
137
138/**
139 * Write data from a user-provided callback into a FIFO.
140 *
141 * @param f the FIFO buffer
142 * @param read_cb Callback supplying the data to the FIFO. May be called
143 * multiple times.
144 * @param opaque opaque user data to be provided to read_cb
145 * @param nb_elems Should point to the maximum number of elements that can be
146 * written. Will be updated to contain the number of elements
147 * actually written.
148 *
149 * @return non-negative number on success, a negative error code on failure
150 */
152 void *opaque, size_t *nb_elems);
153
154/**
155 * Read data from a FIFO.
156 *
157 * In case nb_elems > av_fifo_can_read(f), nothing is read and an error
158 * is returned.
159 *
160 * @param f the FIFO buffer
161 * @param buf Buffer to store the data. nb_elems * av_fifo_elem_size(f) bytes
162 * will be written into buf on success.
163 * @param nb_elems number of elements to read from FIFO
164 *
165 * @return a non-negative number on success, a negative error code on failure
166 */
167int av_fifo_read(AVFifo *f, void *buf, size_t nb_elems);
168
169/**
170 * Feed data from a FIFO into a user-provided callback.
171 *
172 * @param f the FIFO buffer
173 * @param write_cb Callback the data will be supplied to. May be called
174 * multiple times.
175 * @param opaque opaque user data to be provided to write_cb
176 * @param nb_elems Should point to the maximum number of elements that can be
177 * read. Will be updated to contain the total number of elements
178 * actually sent to the callback.
179 *
180 * @return non-negative number on success, a negative error code on failure
181 */
183 void *opaque, size_t *nb_elems);
184
185/**
186 * Read data from a FIFO without modifying FIFO state.
187 *
188 * Returns an error if an attempt is made to peek to nonexistent elements
189 * (i.e. if offset + nb_elems is larger than av_fifo_can_read(f)).
190 *
191 * @param f the FIFO buffer
192 * @param buf Buffer to store the data. nb_elems * av_fifo_elem_size(f) bytes
193 * will be written into buf.
194 * @param nb_elems number of elements to read from FIFO
195 * @param offset number of initial elements to skip.
196 *
197 * @return a non-negative number on success, a negative error code on failure
198 */
199int av_fifo_peek(const AVFifo *f, void *buf, size_t nb_elems, size_t offset);
200
201/**
202 * Feed data from a FIFO into a user-provided callback.
203 *
204 * @param f the FIFO buffer
205 * @param write_cb Callback the data will be supplied to. May be called
206 * multiple times.
207 * @param opaque opaque user data to be provided to write_cb
208 * @param nb_elems Should point to the maximum number of elements that can be
209 * read. Will be updated to contain the total number of elements
210 * actually sent to the callback.
211 * @param offset number of initial elements to skip; offset + *nb_elems must not
212 * be larger than av_fifo_can_read(f).
213 *
214 * @return a non-negative number on success, a negative error code on failure
215 */
216int av_fifo_peek_to_cb(const AVFifo *f, AVFifoCB write_cb, void *opaque,
217 size_t *nb_elems, size_t offset);
218
219/**
220 * Discard the specified amount of data from an AVFifo.
221 * @param size number of elements to discard, MUST NOT be larger than
222 * av_fifo_can_read(f)
223 */
224void av_fifo_drain2(AVFifo *f, size_t size);
225
226/*
227 * Empty the AVFifo.
228 * @param f AVFifo to reset
229 */
231
232/**
233 * Free an AVFifo and reset pointer to NULL.
234 * @param f Pointer to an AVFifo to free. *f == NULL is allowed.
235 */
237
238/**
239 * @}
240 */
241
242#endif /* AVUTIL_FIFO_H */
AVFifo * av_fifo_alloc2(size_t elems, size_t elem_size, unsigned int flags)
Allocate and initialize an AVFifo with a given element size.
void av_fifo_freep2(AVFifo **f)
Free an AVFifo and reset pointer to NULL.
void av_fifo_reset2(AVFifo *f)
size_t av_fifo_can_write(const AVFifo *f)
size_t av_fifo_can_read(const AVFifo *f)
int av_fifo_peek(const AVFifo *f, void *buf, size_t nb_elems, size_t offset)
Read data from a FIFO without modifying FIFO state.
int av_fifo_read_to_cb(AVFifo *f, AVFifoCB write_cb, void *opaque, size_t *nb_elems)
Feed data from a FIFO into a user-provided callback.
size_t av_fifo_elem_size(const AVFifo *f)
int av_fifo_write_from_cb(AVFifo *f, AVFifoCB read_cb, void *opaque, size_t *nb_elems)
Write data from a user-provided callback into a FIFO.
int av_fifo_grow2(AVFifo *f, size_t inc)
Enlarge an AVFifo.
struct AVFifo AVFifo
Definition fifo.h:38
int av_fifo_peek_to_cb(const AVFifo *f, AVFifoCB write_cb, void *opaque, size_t *nb_elems, size_t offset)
Feed data from a FIFO into a user-provided callback.
int AVFifoCB(void *opaque, void *buf, size_t *nb_elems)
Callback for writing or reading from a FIFO, passed to (and invoked from) the av_fifo_*_cb() function...
Definition fifo.h:56
int av_fifo_write(AVFifo *f, const void *buf, size_t nb_elems)
Write data into a FIFO.
void av_fifo_auto_grow_limit(AVFifo *f, size_t max_elems)
Set the maximum size (in elements) to which the FIFO can be resized automatically.
void av_fifo_drain2(AVFifo *f, size_t size)
Discard the specified amount of data from an AVFifo.
int av_fifo_read(AVFifo *f, void *buf, size_t nb_elems)
Read data from a FIFO.