fifo.h 4.06 KB
Newer Older
1
/*
2
 * This file is part of Libav.
3
 *
4
 * Libav is free software; you can redistribute it and/or
5 6 7 8
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
9
 * Libav is distributed in the hope that it will be useful,
10 11 12 13 14
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * 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 17 18
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

19
/**
20
 * @file
21
 * a very simple circular buffer FIFO implementation
22 23
 */

24 25
#ifndef AVUTIL_FIFO_H
#define AVUTIL_FIFO_H
26

27
#include <stdint.h>
28
#include "avutil.h"
29
#include "attributes.h"
30

31 32 33
typedef struct AVFifoBuffer {
    uint8_t *buffer;
    uint8_t *rptr, *wptr, *end;
34
    uint32_t rndx, wndx;
35 36
} AVFifoBuffer;

37
/**
38
 * Initialize an AVFifoBuffer.
39
 * @param size of FIFO
40
 * @return AVFifoBuffer or NULL in case of memory allocation failure
41
 */
42
AVFifoBuffer *av_fifo_alloc(unsigned int size);
43 44

/**
45
 * Free an AVFifoBuffer.
46
 * @param f AVFifoBuffer to free
47
 */
48
void av_fifo_free(AVFifoBuffer *f);
49

50
/**
51
 * Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
52
 * @param f AVFifoBuffer to reset
53 54 55
 */
void av_fifo_reset(AVFifoBuffer *f);

56
/**
57
 * Return the amount of data in bytes in the AVFifoBuffer, that is the
58
 * amount of data you can read from it.
59
 * @param f AVFifoBuffer to read from
60 61
 * @return size
 */
62
int av_fifo_size(AVFifoBuffer *f);
63

64
/**
65
 * Return the amount of space in bytes in the AVFifoBuffer, that is the
66
 * amount of data you can write into it.
67
 * @param f AVFifoBuffer to write into
68 69 70 71
 * @return size
 */
int av_fifo_space(AVFifoBuffer *f);

72
/**
73
 * Feed data from an AVFifoBuffer to a user-supplied callback.
74
 * @param f AVFifoBuffer to read from
75
 * @param buf_size number of bytes to read
76 77
 * @param func generic read function
 * @param dest data destination
78
 */
79
int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
80

81
/**
82
 * Feed data from a user-supplied callback to an AVFifoBuffer.
83 84
 * @param f AVFifoBuffer to write to
 * @param src data source; non-const since it may be used as a
85
 * modifiable context by the function defined in func
86
 * @param size number of bytes to write
87
 * @param func generic write function; the first parameter is src,
88
 * the second is dest_buf, the third is dest_buf_size.
89 90
 * func must return the number of bytes written to dest_buf, or <= 0 to
 * indicate no more data available to write.
91
 * If func is NULL, src is interpreted as a simple byte array for source data.
92
 * @return the number of bytes written to the FIFO
93
 */
94
int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
95

96
/**
97
 * Resize an AVFifoBuffer.
98
 * @param f AVFifoBuffer to resize
99
 * @param size new AVFifoBuffer size in bytes
100
 * @return <0 for failure, >=0 otherwise
101 102 103
 */
int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);

104
/**
105
 * Read and discard the specified amount of data from an AVFifoBuffer.
106
 * @param f AVFifoBuffer to read from
107
 * @param size amount of data to read in bytes
108
 */
109 110
void av_fifo_drain(AVFifoBuffer *f, int size);

111 112 113 114
/**
 * Return a pointer to the data stored in a FIFO buffer at a certain offset.
 * The FIFO buffer is not modified.
 *
115
 * @param f    AVFifoBuffer to peek at, f must be non-NULL
116 117 118 119 120 121
 * @param offs an offset in bytes, its absolute value must be less
 *             than the used buffer size or the returned pointer will
 *             point outside to the buffer data.
 *             The used buffer size can be checked with av_fifo_size().
 */
static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
122 123 124
{
    uint8_t *ptr = f->rptr + offs;
    if (ptr >= f->end)
125 126 127 128
        ptr = f->buffer + (ptr - f->end);
    else if (ptr < f->buffer)
        ptr = f->end - (f->buffer - ptr);
    return ptr;
129
}
130

131
#endif /* AVUTIL_FIFO_H */