atomics: cosmetics: Restructure ifdefs for greater clarity
[libav.git] / libavutil / atomic.h
1 /*
2 * Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
3 *
4 * This file is part of Libav.
5 *
6 * Libav 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 * Libav 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 Libav; 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_NATIVE
27
28 #if HAVE_ATOMICS_GCC
29 #include "atomic_gcc.h"
30 #elif HAVE_ATOMICS_WIN32
31 #include "atomic_win32.h"
32 #elif HAVE_ATOMICS_SUNCC
33 #include "atomic_suncc.h"
34 #endif
35
36 #else
37
38 /**
39 * Load the current value stored in an atomic integer.
40 *
41 * @param ptr atomic integer
42 * @return the current value of the atomic integer
43 * @note This acts as a memory barrier.
44 */
45 int avpriv_atomic_int_get(volatile int *ptr);
46
47 /**
48 * Store a new value in an atomic integer.
49 *
50 * @param ptr atomic integer
51 * @param val the value to store in the atomic integer
52 * @note This acts as a memory barrier.
53 */
54 void avpriv_atomic_int_set(volatile int *ptr, int val);
55
56 /**
57 * Add a value to an atomic integer.
58 *
59 * @param ptr atomic integer
60 * @param inc the value to add to the atomic integer (may be negative)
61 * @return the new value of the atomic integer.
62 * @note This does NOT act as a memory barrier. This is primarily
63 * intended for reference counting.
64 */
65 int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc);
66
67 /**
68 * Atomic pointer compare and swap.
69 *
70 * @param ptr pointer to the pointer to operate on
71 * @param oldval do the swap if the current value of *ptr equals to oldval
72 * @param newval value to replace *ptr with
73 * @return the value of *ptr before comparison
74 */
75 void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval);
76
77 #endif /* HAVE_ATOMICS_NATIVE */
78
79 #endif /* AVUTIL_ATOMIC_H */