2 * This file is part of FFmpeg.
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.
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.
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
21 * a very simple circular buffer FIFO implementation
29 #include "attributes.h"
31 typedef struct AVFifoBuffer {
33 uint8_t *rptr, *wptr, *end;
38 * Initialize an AVFifoBuffer.
40 * @return AVFifoBuffer or NULL in case of memory allocation failure
42 AVFifoBuffer *av_fifo_alloc(unsigned int size);
45 * Initialize an AVFifoBuffer.
46 * @param nmemb number of elements
47 * @param size size of the single element
48 * @return AVFifoBuffer or NULL in case of memory allocation failure
50 AVFifoBuffer *av_fifo_alloc_array(size_t nmemb, size_t size);
53 * Free an AVFifoBuffer.
54 * @param f AVFifoBuffer to free
56 void av_fifo_free(AVFifoBuffer *f);
59 * Free an AVFifoBuffer and reset pointer to NULL.
60 * @param f AVFifoBuffer to free
62 void av_fifo_freep(AVFifoBuffer **f);
65 * Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
66 * @param f AVFifoBuffer to reset
68 void av_fifo_reset(AVFifoBuffer *f);
71 * Return the amount of data in bytes in the AVFifoBuffer, that is the
72 * amount of data you can read from it.
73 * @param f AVFifoBuffer to read from
76 int av_fifo_size(const AVFifoBuffer *f);
79 * Return the amount of space in bytes in the AVFifoBuffer, that is the
80 * amount of data you can write into it.
81 * @param f AVFifoBuffer to write into
84 int av_fifo_space(const AVFifoBuffer *f);
87 * Feed data from an AVFifoBuffer to a user-supplied callback.
88 * Similar as av_fifo_gereric_read but without discarding data.
89 * @param f AVFifoBuffer to read from
90 * @param buf_size number of bytes to read
91 * @param func generic read function
92 * @param dest data destination
94 int av_fifo_generic_peek(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
97 * Feed data from an AVFifoBuffer to a user-supplied callback.
98 * @param f AVFifoBuffer to read from
99 * @param buf_size number of bytes to read
100 * @param func generic read function
101 * @param dest data destination
103 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
106 * Feed data from a user-supplied callback to an AVFifoBuffer.
107 * @param f AVFifoBuffer to write to
108 * @param src data source; non-const since it may be used as a
109 * modifiable context by the function defined in func
110 * @param size number of bytes to write
111 * @param func generic write function; the first parameter is src,
112 * the second is dest_buf, the third is dest_buf_size.
113 * func must return the number of bytes written to dest_buf, or <= 0 to
114 * indicate no more data available to write.
115 * If func is NULL, src is interpreted as a simple byte array for source data.
116 * @return the number of bytes written to the FIFO
118 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
121 * Resize an AVFifoBuffer.
122 * In case of reallocation failure, the old FIFO is kept unchanged.
124 * @param f AVFifoBuffer to resize
125 * @param size new AVFifoBuffer size in bytes
126 * @return <0 for failure, >=0 otherwise
128 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
131 * Enlarge an AVFifoBuffer.
132 * In case of reallocation failure, the old FIFO is kept unchanged.
133 * The new fifo size may be larger than the requested size.
135 * @param f AVFifoBuffer to resize
136 * @param additional_space the amount of space in bytes to allocate in addition to av_fifo_size()
137 * @return <0 for failure, >=0 otherwise
139 int av_fifo_grow(AVFifoBuffer *f, unsigned int additional_space);
142 * Read and discard the specified amount of data from an AVFifoBuffer.
143 * @param f AVFifoBuffer to read from
144 * @param size amount of data to read in bytes
146 void av_fifo_drain(AVFifoBuffer *f, int size);
149 * Return a pointer to the data stored in a FIFO buffer at a certain offset.
150 * The FIFO buffer is not modified.
152 * @param f AVFifoBuffer to peek at, f must be non-NULL
153 * @param offs an offset in bytes, its absolute value must be less
154 * than the used buffer size or the returned pointer will
155 * point outside to the buffer data.
156 * The used buffer size can be checked with av_fifo_size().
158 static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
160 uint8_t *ptr = f->rptr + offs;
162 ptr = f->buffer + (ptr - f->end);
163 else if (ptr < f->buffer)
164 ptr = f->end - (f->buffer - ptr);
168 #endif /* AVUTIL_FIFO_H */