Make av_get_random_seed() non-blocking
[libav.git] / libavutil / 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
1faf7dc8 19/**
ba87f080 20 * @file
89c9ff50 21 * a very simple circular buffer FIFO implementation
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22 */
23
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24#ifndef AVUTIL_FIFO_H
25#define AVUTIL_FIFO_H
f5a478f6 26
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27#include <stdint.h>
28
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29typedef struct AVFifoBuffer {
30 uint8_t *buffer;
31 uint8_t *rptr, *wptr, *end;
0a71e78c 32 uint32_t rndx, wndx;
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33} AVFifoBuffer;
34
1faf7dc8 35/**
82ffe191 36 * Initializes an AVFifoBuffer.
1faf7dc8 37 * @param size of FIFO
b9bd6589 38 * @return AVFifoBuffer or NULL in case of memory allocation failure
1faf7dc8 39 */
41dd680d 40AVFifoBuffer *av_fifo_alloc(unsigned int size);
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41
42/**
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43 * Frees an AVFifoBuffer.
44 * @param *f AVFifoBuffer to free
1faf7dc8 45 */
f5a478f6 46void av_fifo_free(AVFifoBuffer *f);
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47
48/**
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49 * Resets the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
50 * @param *f AVFifoBuffer to reset
51 */
52void av_fifo_reset(AVFifoBuffer *f);
53
54/**
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55 * Returns the amount of data in bytes in the AVFifoBuffer, that is the
56 * amount of data you can read from it.
57 * @param *f AVFifoBuffer to read from
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58 * @return size
59 */
f5a478f6 60int av_fifo_size(AVFifoBuffer *f);
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61
62/**
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63 * Returns the amount of space in bytes in the AVFifoBuffer, that is the
64 * amount of data you can write into it.
65 * @param *f AVFifoBuffer to write into
66 * @return size
67 */
68int av_fifo_space(AVFifoBuffer *f);
69
70/**
89c9ff50 71 * Feeds data from an AVFifoBuffer to a user-supplied callback.
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72 * @param *f AVFifoBuffer to read from
73 * @param buf_size number of bytes to read
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74 * @param *func generic read function
75 * @param *dest data destination
1faf7dc8 76 */
3898eed8 77int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
1faf7dc8 78
49cec199 79/**
89c9ff50 80 * Feeds data from a user-supplied callback to an AVFifoBuffer.
49cec199 81 * @param *f AVFifoBuffer to write to
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82 * @param *src data source; non-const since it may be used as a
83 * modifiable context by the function defined in func
49cec199 84 * @param size number of bytes to write
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85 * @param *func generic write function; the first parameter is src,
86 * the second is dest_buf, the third is dest_buf_size.
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87 * func must return the number of bytes written to dest_buf, or <= 0 to
88 * indicate no more data available to write.
95c76e11 89 * If func is NULL, src is interpreted as a simple byte array for source data.
89c9ff50 90 * @return the number of bytes written to the FIFO
49cec199 91 */
95c76e11 92int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
1faf7dc8 93
1faf7dc8 94/**
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95 * Resizes an AVFifoBuffer.
96 * @param *f AVFifoBuffer to resize
97 * @param size new AVFifoBuffer size in bytes
89c9ff50 98 * @return <0 for failure, >=0 otherwise
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99 */
100int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
101
102/**
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103 * Reads and discards the specified amount of data from an AVFifoBuffer.
104 * @param *f AVFifoBuffer to read from
105 * @param size amount of data to read in bytes
1faf7dc8 106 */
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107void av_fifo_drain(AVFifoBuffer *f, int size);
108
109static inline uint8_t av_fifo_peek(AVFifoBuffer *f, int offs)
110{
111 uint8_t *ptr = f->rptr + offs;
112 if (ptr >= f->end)
113 ptr -= f->end - f->buffer;
114 return *ptr;
115}
98790382 116#endif /* AVUTIL_FIFO_H */