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
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
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
67__atomic_dec(volatile int *ptr)
68{
69  return __sync_fetch_and_sub (ptr, 1);
70}
71
72__ATOMIC_INLINE__ int
73__atomic_inc(volatile int *ptr)
74{
75  return __sync_fetch_and_add (ptr, 1);
76}
77
78
79int __futex_wait(volatile void *ftx, int val, const struct timespec *timeout);
80int __futex_wake(volatile void *ftx, int count);
81
82__END_DECLS
83
84#endif /* _SYS_ATOMICS_H */
85