1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28 #ifndef _SYS_ATOMICS_H
29 #define _SYS_ATOMICS_H
30
31 #include <sys/cdefs.h>
32 #include <sys/time.h>
33
34 __BEGIN_DECLS
35
36 /* Note: atomic operations that were exported by the C library didn't
37 * provide any memory barriers, which created potential issues on
38 * multi-core devices. We now define them as inlined calls to
39 * GCC sync builtins, which always provide a full barrier.
40 *
41 * NOTE: The C library still exports atomic functions by the same
42 * name to ensure ABI stability for existing NDK machine code.
43 *
44 * If you are an NDK developer, we encourage you to rebuild your
45 * unmodified sources against this header as soon as possible.
46 */
47 #define __ATOMIC_INLINE__ static __inline__ __attribute__((always_inline))
48
49 __ATOMIC_INLINE__ int
__atomic_cmpxchg(int old,int _new,volatile int * ptr)50 __atomic_cmpxchg(int old, int _new, volatile int *ptr)
51 {
52 /* We must return 0 on success */
53 return __sync_val_compare_and_swap(ptr, old, _new) != old;
54 }
55
56 __ATOMIC_INLINE__ int
__atomic_swap(int _new,volatile int * ptr)57 __atomic_swap(int _new, volatile int *ptr)
58 {
59 int prev;
60 do {
61 prev = *ptr;
62 } while (__sync_val_compare_and_swap(ptr, prev, _new) != prev);
63 return prev;
64 }
65
66 __ATOMIC_INLINE__ int
__atomic_dec(volatile int * ptr)67 __atomic_dec(volatile int *ptr)
68 {
69 return __sync_fetch_and_sub (ptr, 1);
70 }
71
72 __ATOMIC_INLINE__ int
__atomic_inc(volatile int * ptr)73 __atomic_inc(volatile int *ptr)
74 {
75 return __sync_fetch_and_add (ptr, 1);
76 }
77
78
79 int __futex_wait(volatile void *ftx, int val, const struct timespec *timeout);
80 int __futex_wake(volatile void *ftx, int count);
81
82 __END_DECLS
83
84 #endif /* _SYS_ATOMICS_H */
85