libavutil/buffer_internal.h

   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 <stdatomic.h>
  23 #include <stdint.h>
  24
  25 #include "buffer.h"
  26 #include "thread.h"
  27
  28 /**
  29  * The buffer was av_realloc()ed, so it is reallocatable.
  30  */
  31 #define BUFFER_FLAG_REALLOCATABLE (1 << 0)
  32 /**
  33  * The AVBuffer structure is part of a larger structure
  34  * and should not be freed.
  35  */
  36 #define BUFFER_FLAG_NO_FREE       (1 << 1)
  37
  38 struct AVBuffer {
  39     uint8_t *data; /**< data described by this buffer */
  40     size_t size; /**< size of data in bytes */
  41
  42     /**
  43      *  number of existing AVBufferRef instances referring to this buffer
  44      */
  45     atomic_uint refcount;
  46
  47     /**
  48      * a callback for freeing the data
  49      */
  50     void (*free)(void *opaque, uint8_t *data);
  51
  52     /**
  53      * an opaque pointer, to be used by the freeing callback
  54      */
  55     void *opaque;
  56
  57     /**
  58      * A combination of AV_BUFFER_FLAG_*
  59      */
  60     int flags;
  61
  62     /**
  63      * A combination of BUFFER_FLAG_*
  64      */
  65     int flags_internal;
  66 };
  67
  68 typedef struct BufferPoolEntry {
  69     uint8_t *data;
  70
  71     /*
  72      * Backups of the original opaque/free of the AVBuffer corresponding to
  73      * data. They will be used to free the buffer when the pool is freed.
  74      */
  75     void *opaque;
  76     void (*free)(void *opaque, uint8_t *data);
  77
  78     AVBufferPool *pool;
  79     struct BufferPoolEntry *next;
  80
  81     /*
  82      * An AVBuffer structure to (re)use as AVBuffer for subsequent uses
  83      * of this BufferPoolEntry.
  84      */
  85     AVBuffer buffer;
  86 } BufferPoolEntry;
  87
  88 struct AVBufferPool {
  89     AVMutex mutex;
  90     BufferPoolEntry *pool;
  91
  92     /*
  93      * This is used to track when the pool is to be freed.
  94      * The pointer to the pool itself held by the caller is considered to
  95      * be one reference. Each buffer requested by the caller increases refcount
  96      * by one, returning the buffer to the pool decreases it by one.
  97      * refcount reaches zero when the buffer has been uninited AND all the
  98      * buffers have been released, then it's safe to free the pool and all
  99      * the buffers in it.
 100      */
 101     atomic_uint refcount;
 102
 103     size_t size;
 104     void *opaque;
 105     AVBufferRef* (*alloc)(size_t size);
 106     AVBufferRef* (*alloc2)(void *opaque, size_t size);
 107     void         (*pool_free)(void *opaque);
 108 };
 109
 110 #endif /* AVUTIL_BUFFER_INTERNAL_H */