FFmpeg 7.0.2
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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#include <stdint.h>
30
31#include "attributes.h"
32#include "version.h"
33
34/**
35 * @defgroup lavu_fifo AVFifo
36 * @ingroup lavu_data
37 *
38 * @{
39 * A generic FIFO API
40 */
41
42typedef struct AVFifo AVFifo;
43
44/**
45 * Callback for writing or reading from a FIFO, passed to (and invoked from) the
46 * av_fifo_*_cb() functions. It may be invoked multiple times from a single
47 * av_fifo_*_cb() call and may process less data than the maximum size indicated
48 * by nb_elems.
49 *
50 * @param opaque the opaque pointer provided to the av_fifo_*_cb() function
51 * @param buf the buffer for reading or writing the data, depending on which
52 * av_fifo_*_cb function is called
53 * @param nb_elems On entry contains the maximum number of elements that can be
54 * read from / written into buf. On success, the callback should
55 * update it to contain the number of elements actually written.
56 *
57 * @return 0 on success, a negative error code on failure (will be returned from
58 * the invoking av_fifo_*_cb() function)
59 */
60typedef int AVFifoCB(void *opaque, void *buf, size_t *nb_elems);
61
62/**
63 * Automatically resize the FIFO on writes, so that the data fits. This
64 * automatic resizing happens up to a limit that can be modified with
65 * av_fifo_auto_grow_limit().
66 */
67#define AV_FIFO_FLAG_AUTO_GROW (1 << 0)
68
69/**
70 * Allocate and initialize an AVFifo with a given element size.
71 *
72 * @param elems initial number of elements that can be stored in the FIFO
73 * @param elem_size Size in bytes of a single element. Further operations on
74 * the returned FIFO will implicitly use this element size.
75 * @param flags a combination of AV_FIFO_FLAG_*
76 *
77 * @return newly-allocated AVFifo on success, a negative error code on failure
78 */
79AVFifo *av_fifo_alloc2(size_t elems, size_t elem_size,
80 unsigned int flags);
81
82/**
83 * @return Element size for FIFO operations. This element size is set at
84 * FIFO allocation and remains constant during its lifetime
85 */
86size_t av_fifo_elem_size(const AVFifo *f);
87
88/**
89 * Set the maximum size (in elements) to which the FIFO can be resized
90 * automatically. Has no effect unless AV_FIFO_FLAG_AUTO_GROW is used.
91 */
92void av_fifo_auto_grow_limit(AVFifo *f, size_t max_elems);
93
94/**
95 * @return number of elements available for reading from the given FIFO.
96 */
97size_t av_fifo_can_read(const AVFifo *f);
98
99/**
100 * @return Number of elements that can be written into the given FIFO without
101 * growing it.
102 *
103 * In other words, this number of elements or less is guaranteed to fit
104 * into the FIFO. More data may be written when the
105 * AV_FIFO_FLAG_AUTO_GROW flag was specified at FIFO creation, but this
106 * may involve memory allocation, which can fail.
107 */
108size_t av_fifo_can_write(const AVFifo *f);
109
110/**
111 * Enlarge an AVFifo.
112 *
113 * On success, the FIFO will be large enough to hold exactly
114 * inc + av_fifo_can_read() + av_fifo_can_write()
115 * elements. In case of failure, the old FIFO is kept unchanged.
116 *
117 * @param f AVFifo to resize
118 * @param inc number of elements to allocate for, in addition to the current
119 * allocated size
120 * @return a non-negative number on success, a negative error code on failure
121 */
122int av_fifo_grow2(AVFifo *f, size_t inc);
123
124/**
125 * Write data into a FIFO.
126 *
127 * In case nb_elems > av_fifo_can_write(f) and the AV_FIFO_FLAG_AUTO_GROW flag
128 * was not specified at FIFO creation, nothing is written and an error
129 * is returned.
130 *
131 * Calling function is guaranteed to succeed if nb_elems <= av_fifo_can_write(f).
132 *
133 * @param f the FIFO buffer
134 * @param buf Data to be written. nb_elems * av_fifo_elem_size(f) bytes will be
135 * read from buf on success.
136 * @param nb_elems number of elements to write into FIFO
137 *
138 * @return a non-negative number on success, a negative error code on failure
139 */
140int av_fifo_write(AVFifo *f, const void *buf, size_t nb_elems);
141
142/**
143 * Write data from a user-provided callback into a FIFO.
144 *
145 * @param f the FIFO buffer
146 * @param read_cb Callback supplying the data to the FIFO. May be called
147 * multiple times.
148 * @param opaque opaque user data to be provided to read_cb
149 * @param nb_elems Should point to the maximum number of elements that can be
150 * written. Will be updated to contain the number of elements
151 * actually written.
152 *
153 * @return non-negative number on success, a negative error code on failure
154 */
156 void *opaque, size_t *nb_elems);
157
158/**
159 * Read data from a FIFO.
160 *
161 * In case nb_elems > av_fifo_can_read(f), nothing is read and an error
162 * is returned.
163 *
164 * @param f the FIFO buffer
165 * @param buf Buffer to store the data. nb_elems * av_fifo_elem_size(f) bytes
166 * will be written into buf on success.
167 * @param nb_elems number of elements to read from FIFO
168 *
169 * @return a non-negative number on success, a negative error code on failure
170 */
171int av_fifo_read(AVFifo *f, void *buf, size_t nb_elems);
172
173/**
174 * Feed data from a FIFO into a user-provided callback.
175 *
176 * @param f the FIFO buffer
177 * @param write_cb Callback the data will be supplied to. May be called
178 * multiple times.
179 * @param opaque opaque user data to be provided to write_cb
180 * @param nb_elems Should point to the maximum number of elements that can be
181 * read. Will be updated to contain the total number of elements
182 * actually sent to the callback.
183 *
184 * @return non-negative number on success, a negative error code on failure
185 */
187 void *opaque, size_t *nb_elems);
188
189/**
190 * Read data from a FIFO without modifying FIFO state.
191 *
192 * Returns an error if an attempt is made to peek to nonexistent elements
193 * (i.e. if offset + nb_elems is larger than av_fifo_can_read(f)).
194 *
195 * @param f the FIFO buffer
196 * @param buf Buffer to store the data. nb_elems * av_fifo_elem_size(f) bytes
197 * will be written into buf.
198 * @param nb_elems number of elements to read from FIFO
199 * @param offset number of initial elements to skip.
200 *
201 * @return a non-negative number on success, a negative error code on failure
202 */
203int av_fifo_peek(const AVFifo *f, void *buf, size_t nb_elems, size_t offset);
204
205/**
206 * Feed data from a FIFO into a user-provided callback.
207 *
208 * @param f the FIFO buffer
209 * @param write_cb Callback the data will be supplied to. May be called
210 * multiple times.
211 * @param opaque opaque user data to be provided to write_cb
212 * @param nb_elems Should point to the maximum number of elements that can be
213 * read. Will be updated to contain the total number of elements
214 * actually sent to the callback.
215 * @param offset number of initial elements to skip; offset + *nb_elems must not
216 * be larger than av_fifo_can_read(f).
217 *
218 * @return a non-negative number on success, a negative error code on failure
219 */
220int av_fifo_peek_to_cb(const AVFifo *f, AVFifoCB write_cb, void *opaque,
221 size_t *nb_elems, size_t offset);
222
223/**
224 * Discard the specified amount of data from an AVFifo.
225 * @param size number of elements to discard, MUST NOT be larger than
226 * av_fifo_can_read(f)
227 */
228void av_fifo_drain2(AVFifo *f, size_t size);
229
230/*
231 * Empty the AVFifo.
232 * @param f AVFifo to reset
233 */
235
236/**
237 * Free an AVFifo and reset pointer to NULL.
238 * @param f Pointer to an AVFifo to free. *f == NULL is allowed.
239 */
241
242/**
243 * @}
244 */
245
246#endif /* AVUTIL_FIFO_H */
Macro definitions for various function/variable attributes.
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:42
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:60
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.
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