threads: Check w32threads dependencies at the configure stage
[libav.git] / libavutil / atomic.c
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 "config.h"
22 #include "atomic.h"
23
24 #if !HAVE_ATOMICS_NATIVE
25
26 #if HAVE_PTHREADS
27
28 #include <pthread.h>
29
30 static pthread_mutex_t atomic_lock = PTHREAD_MUTEX_INITIALIZER;
31
32 int avpriv_atomic_int_get(volatile int *ptr)
33 {
34 int res;
35
36 pthread_mutex_lock(&atomic_lock);
37 res = *ptr;
38 pthread_mutex_unlock(&atomic_lock);
39
40 return res;
41 }
42
43 void avpriv_atomic_int_set(volatile int *ptr, int val)
44 {
45 pthread_mutex_lock(&atomic_lock);
46 *ptr = val;
47 pthread_mutex_unlock(&atomic_lock);
48 }
49
50 int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc)
51 {
52 int res;
53
54 pthread_mutex_lock(&atomic_lock);
55 *ptr += inc;
56 res = *ptr;
57 pthread_mutex_unlock(&atomic_lock);
58
59 return res;
60 }
61
62 void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
63 {
64 void *ret;
65 pthread_mutex_lock(&atomic_lock);
66 ret = *ptr;
67 if (*ptr == oldval)
68 *ptr = newval;
69 pthread_mutex_unlock(&atomic_lock);
70 return ret;
71 }
72
73 #elif !HAVE_THREADS
74
75 int avpriv_atomic_int_get(volatile int *ptr)
76 {
77 return *ptr;
78 }
79
80 void avpriv_atomic_int_set(volatile int *ptr, int val)
81 {
82 *ptr = val;
83 }
84
85 int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc)
86 {
87 *ptr += inc;
88 return *ptr;
89 }
90
91 void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
92 {
93 if (*ptr == oldval) {
94 *ptr = newval;
95 return oldval;
96 }
97 return *ptr;
98 }
99
100 #else /* HAVE_THREADS */
101
102 /* This should never trigger, unless a new threading implementation
103 * without correct atomics dependencies in configure or a corresponding
104 * atomics implementation is added. */
105 #error "Threading is enabled, but there is no implementation of atomic operations available"
106
107 #endif /* HAVE_PTHREADS */
108
109 #endif /* !HAVE_ATOMICS_NATIVE */
110
111 #ifdef TEST
112 #include <assert.h>
113
114 int main(void)
115 {
116 volatile int val = 1;
117 int res;
118
119 res = avpriv_atomic_int_add_and_fetch(&val, 1);
120 assert(res == 2);
121 avpriv_atomic_int_set(&val, 3);
122 res = avpriv_atomic_int_get(&val);
123 assert(res == 3);
124
125 return 0;
126 }
127 #endif