f106239304b29c8c138edaacf9682acd11edc539
[libav.git] / libavutil / fifo.h
1 /*
2 * This file is part of Libav.
3 *
4 * Libav 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 * Libav 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 Libav; 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 * a very simple circular buffer FIFO implementation
22 */
23
24 #ifndef AVUTIL_FIFO_H
25 #define AVUTIL_FIFO_H
26
27 #include <stdint.h>
28 #include "avutil.h"
29
30 typedef struct AVFifoBuffer {
31 uint8_t *buffer;
32 uint8_t *rptr, *wptr, *end;
33 uint32_t rndx, wndx;
34 } AVFifoBuffer;
35
36 /**
37 * Initialize an AVFifoBuffer.
38 * @param size of FIFO
39 * @return AVFifoBuffer or NULL in case of memory allocation failure
40 */
41 AVFifoBuffer *av_fifo_alloc(unsigned int size);
42
43 /**
44 * Free an AVFifoBuffer.
45 * @param f AVFifoBuffer to free
46 */
47 void av_fifo_free(AVFifoBuffer *f);
48
49 /**
50 * Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
51 * @param f AVFifoBuffer to reset
52 */
53 void av_fifo_reset(AVFifoBuffer *f);
54
55 /**
56 * Return the amount of data in bytes in the AVFifoBuffer, that is the
57 * amount of data you can read from it.
58 * @param f AVFifoBuffer to read from
59 * @return size
60 */
61 int av_fifo_size(AVFifoBuffer *f);
62
63 /**
64 * Return the amount of space in bytes in the AVFifoBuffer, that is the
65 * amount of data you can write into it.
66 * @param f AVFifoBuffer to write into
67 * @return size
68 */
69 int av_fifo_space(AVFifoBuffer *f);
70
71 /**
72 * Feed data from an AVFifoBuffer to a user-supplied callback.
73 * @param f AVFifoBuffer to read from
74 * @param buf_size number of bytes to read
75 * @param func generic read function
76 * @param dest data destination
77 */
78 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
79
80 /**
81 * Feed data from a user-supplied callback to an AVFifoBuffer.
82 * @param f AVFifoBuffer to write to
83 * @param src data source; non-const since it may be used as a
84 * modifiable context by the function defined in func
85 * @param size number of bytes to write
86 * @param func generic write function; the first parameter is src,
87 * the second is dest_buf, the third is dest_buf_size.
88 * func must return the number of bytes written to dest_buf, or <= 0 to
89 * indicate no more data available to write.
90 * If func is NULL, src is interpreted as a simple byte array for source data.
91 * @return the number of bytes written to the FIFO
92 */
93 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
94
95 /**
96 * Resize an AVFifoBuffer.
97 * @param f AVFifoBuffer to resize
98 * @param size new AVFifoBuffer size in bytes
99 * @return <0 for failure, >=0 otherwise
100 */
101 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
102
103 /**
104 * Read and discard the specified amount of data from an AVFifoBuffer.
105 * @param f AVFifoBuffer to read from
106 * @param size amount of data to read in bytes
107 */
108 void av_fifo_drain(AVFifoBuffer *f, int size);
109
110 /**
111 * Return a pointer to the data stored in a FIFO buffer at a certain offset.
112 * The FIFO buffer is not modified.
113 *
114 * @param f AVFifoBuffer to peek at, f must be non-NULL
115 * @param offs an offset in bytes, its absolute value must be less
116 * than the used buffer size or the returned pointer will
117 * point outside to the buffer data.
118 * The used buffer size can be checked with av_fifo_size().
119 */
120 static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
121 {
122 uint8_t *ptr = f->rptr + offs;
123 if (ptr >= f->end)
124 ptr = f->buffer + (ptr - f->end);
125 else if (ptr < f->buffer)
126 ptr = f->end - (f->buffer - ptr);
127 return ptr;
128 }
129
130 #if FF_API_AV_FIFO_PEEK
131 /**
132 * @deprecated Use av_fifo_peek2() instead.
133 */
134 attribute_deprecated
135 static inline uint8_t av_fifo_peek(AVFifoBuffer *f, int offs)
136 {
137 return *av_fifo_peek2(f, offs);
138 }
139 #endif
140
141 #endif /* AVUTIL_FIFO_H */