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atomic.h
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1 /*
2  * Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVUTIL_ATOMIC_H
22 #define AVUTIL_ATOMIC_H
23 
24 #include "config.h"
25 
26 #if HAVE_ATOMICS_GCC
27 #include "atomic_gcc.h"
28 #elif HAVE_ATOMICS_WIN32
29 #include "atomic_win32.h"
30 #elif HAVE_ATOMICS_SUNCC
31 #include "atomic_suncc.h"
32 #else
33 
34 /**
35  * Load the current value stored in an atomic integer.
36  *
37  * @param ptr atomic integer
38  * @return the current value of the atomic integer
39  * @note This acts as a memory barrier.
40  */
41 int avpriv_atomic_int_get(volatile int *ptr);
42 
43 /**
44  * Store a new value in an atomic integer.
45  *
46  * @param ptr atomic integer
47  * @param val the value to store in the atomic integer
48  * @note This acts as a memory barrier.
49  */
50 void avpriv_atomic_int_set(volatile int *ptr, int val);
51 
52 /**
53  * Add a value to an atomic integer.
54  *
55  * @param ptr atomic integer
56  * @param inc the value to add to the atomic integer (may be negative)
57  * @return the new value of the atomic integer.
58  * @note This does NOT act as a memory barrier. This is primarily
59  * intended for reference counting.
60  */
61 int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc);
62 
63 /**
64  * Atomic pointer compare and swap.
65  *
66  * @param ptr pointer to the pointer to operate on
67  * @param oldval do the swap if the current value of *ptr equals to oldval
68  * @param newval value to replace *ptr with
69  * @return the value of *ptr before comparison
70  */
71 void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval);
72 
73 #endif /* HAVE_MEMORYBARRIER */
74 #endif /* AVUTIL_ATOMIC_H */