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buffer_internal.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 
19 #ifndef AVUTIL_BUFFER_INTERNAL_H
20 #define AVUTIL_BUFFER_INTERNAL_H
21 
22 #include <stdint.h>
23 
24 #include "buffer.h"
25 
26 /**
27  * The buffer is always treated as read-only.
28  */
29 #define BUFFER_FLAG_READONLY (1 << 0)
30 /**
31  * The buffer was av_realloc()ed, so it is reallocatable.
32  */
33 #define BUFFER_FLAG_REALLOCATABLE (1 << 1)
34 
35 struct AVBuffer {
36  uint8_t *data; /**< data described by this buffer */
37  int size; /**< size of data in bytes */
38 
39  /**
40  * number of existing AVBufferRef instances referring to this buffer
41  */
42  volatile int refcount;
43 
44  /**
45  * a callback for freeing the data
46  */
47  void (*free)(void *opaque, uint8_t *data);
48 
49  /**
50  * an opaque pointer, to be used by the freeing callback
51  */
52  void *opaque;
53 
54  /**
55  * A combination of BUFFER_FLAG_*
56  */
57  int flags;
58 };
59 
60 typedef struct BufferPoolEntry {
62 
63  /*
64  * Backups of the original opaque/free of the AVBuffer corresponding to
65  * data. They will be used to free the buffer when the pool is freed.
66  */
67  void *opaque;
68  void (*free)(void *opaque, uint8_t *data);
69 
71  struct BufferPoolEntry * volatile next;
73 
74 struct AVBufferPool {
75  BufferPoolEntry * volatile pool;
76 
77  /*
78  * This is used to track when the pool is to be freed.
79  * The pointer to the pool itself held by the caller is considered to
80  * be one reference. Each buffer requested by the caller increases refcount
81  * by one, returning the buffer to the pool decreases it by one.
82  * refcount reaches zero when the buffer has been uninited AND all the
83  * buffers have been released, then it's safe to free the pool and all
84  * the buffers in it.
85  */
86  volatile int refcount;
87 
88  volatile int nb_allocated;
89 
90  int size;
91  AVBufferRef* (*alloc)(int size);
92 };
93 
94 #endif /* AVUTIL_BUFFER_INTERNAL_H */