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 * @param f AVFifoBuffer to read from
89 * @param buf_size number of bytes to read
90 * @param func generic read function
91 * @param dest data destination
93 int av_fifo_generic_read(AVFifoBuffer
*f
, void *dest
, int buf_size
, void (*func
)(void*, void*, int));
96 * Feed data from a user-supplied callback to an AVFifoBuffer.
97 * @param f AVFifoBuffer to write to
98 * @param src data source; non-const since it may be used as a
99 * modifiable context by the function defined in func
100 * @param size number of bytes to write
101 * @param func generic write function; the first parameter is src,
102 * the second is dest_buf, the third is dest_buf_size.
103 * func must return the number of bytes written to dest_buf, or <= 0 to
104 * indicate no more data available to write.
105 * If func is NULL, src is interpreted as a simple byte array for source data.
106 * @return the number of bytes written to the FIFO
108 int av_fifo_generic_write(AVFifoBuffer
*f
, void *src
, int size
, int (*func
)(void*, void*, int));
111 * Resize an AVFifoBuffer.
112 * In case of reallocation failure, the old FIFO is kept unchanged.
114 * @param f AVFifoBuffer to resize
115 * @param size new AVFifoBuffer size in bytes
116 * @return <0 for failure, >=0 otherwise
118 int av_fifo_realloc2(AVFifoBuffer
*f
, unsigned int size
);
121 * Enlarge an AVFifoBuffer.
122 * In case of reallocation failure, the old FIFO is kept unchanged.
123 * The new fifo size may be larger than the requested size.
125 * @param f AVFifoBuffer to resize
126 * @param additional_space the amount of space in bytes to allocate in addition to av_fifo_size()
127 * @return <0 for failure, >=0 otherwise
129 int av_fifo_grow(AVFifoBuffer
*f
, unsigned int additional_space
);
132 * Read and discard the specified amount of data from an AVFifoBuffer.
133 * @param f AVFifoBuffer to read from
134 * @param size amount of data to read in bytes
136 void av_fifo_drain(AVFifoBuffer
*f
, int size
);
139 * Return a pointer to the data stored in a FIFO buffer at a certain offset.
140 * The FIFO buffer is not modified.
142 * @param f AVFifoBuffer to peek at, f must be non-NULL
143 * @param offs an offset in bytes, its absolute value must be less
144 * than the used buffer size or the returned pointer will
145 * point outside to the buffer data.
146 * The used buffer size can be checked with av_fifo_size().
148 static inline uint8_t *av_fifo_peek2(const AVFifoBuffer
*f
, int offs
)
150 uint8_t *ptr
= f
->rptr
+ offs
;
152 ptr
= f
->buffer
+ (ptr
- f
->end
);
153 else if (ptr
< f
->buffer
)
154 ptr
= f
->end
- (f
->buffer
- ptr
);
158 #endif /* AVUTIL_FIFO_H */