lavu: add support for atomic operations.
[libav.git] / libavutil / atomic.c
CommitLineData
65f1d45d
RB
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#include "atomic.h"
22
23#if !HAVE_MEMORYBARRIER && !HAVE_SYNC_SYNCHRONIZE && !HAVE_MACHINE_RW_BARRIER
24
25#if HAVE_PTHREADS
26
27#include <pthread.h>
28
29static pthread_mutex_t atomic_lock = PTHREAD_MUTEX_INITIALIZER;
30
31int avpriv_atomic_int_get(volatile int *ptr)
32{
33 int res;
34
35 pthread_mutex_lock(&atomic_lock);
36 res = *ptr;
37 pthread_mutex_unlock(&atomic_lock);
38
39 return res;
40}
41
42void avpriv_atomic_int_set(volatile int *ptr, int val)
43{
44 pthread_mutex_lock(&atomic_lock);
45 *ptr = val;
46 pthread_mutex_unlock(&atomic_lock);
47}
48
49int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc)
50{
51 int res;
52
53 pthread_mutex_lock(&atomic_lock);
54 *ptr += inc;
55 res = *ptr;
56 pthread_mutex_unlock(&atomic_lock);
57
58 return res;
59}
60
61void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
62{
63 void *ret;
64 pthread_mutex_lock(&atomic_lock);
65 ret = *ptr;
66 if (*ptr == oldval)
67 *ptr = newval;
68 pthread_mutex_unlock(&atomic_lock);
69 return ret;
70}
71
72#elif !HAVE_THREADS
73
74int avpriv_atomic_int_get(volatile int *ptr)
75{
76 return *ptr;
77}
78
79void avpriv_atomic_int_set(volatile int *ptr, int val)
80{
81 *ptr = val;
82}
83
84int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc)
85{
86 *ptr += inc;
87 return *ptr;
88}
89
90void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
91{
92 if (*ptr == oldval) {
93 *ptr = newval;
94 return oldval;
95 }
96 return *ptr;
97}
98
99#else
100
101#error "Threading is enabled, but there is no implementation of atomic operations available"
102
103#endif /* HAVE_PTHREADS */
104
105#endif /* !HAVE_MEMORYBARRIER && !HAVE_SYNC_SYNCHRONIZE && !HAVE_MACHINE_RW_BARRIER */
106
107#ifdef TEST
108#include <assert.h>
109
110int main(void)
111{
112 volatile int val = 1;
113 int res;
114
115 res = avpriv_atomic_int_add_and_fetch(&val, 1);
116 assert(res == 2);
117 avpriv_atomic_int_set(&val, 3);
118 res = avpriv_atomic_int_get(&val);
119 assert(res == 3);
120
121 return 0;
122}
123#endif