1 /*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 #ifndef BIONIC_ATOMIC_GCC_BUILTIN_H
17 #define BIONIC_ATOMIC_GCC_BUILTIN_H
18
19 /* This header file is used by default if we don't have optimized atomic
20 * routines for a given platform. See bionic_atomic_arm.h and
21 * bionic_atomic_x86.h for examples.
22 */
23
24 __ATOMIC_INLINE__ void
__bionic_memory_barrier(void)25 __bionic_memory_barrier(void)
26 {
27 __sync_synchronize();
28 }
29
30 __ATOMIC_INLINE__ int
__bionic_cmpxchg(int32_t old_value,int32_t new_value,volatile int32_t * ptr)31 __bionic_cmpxchg(int32_t old_value, int32_t new_value, volatile int32_t* ptr)
32 {
33 /* We must return 0 on success */
34 return __sync_val_compare_and_swap(ptr, old_value, new_value) != old_value;
35 }
36
37 __ATOMIC_INLINE__ int32_t
__bionic_swap(int32_t new_value,volatile int32_t * ptr)38 __bionic_swap(int32_t new_value, volatile int32_t* ptr)
39 {
40 int32_t old_value;
41 do {
42 old_value = *ptr;
43 } while (__sync_val_compare_and_swap(ptr, old_value, new_value) != old_value);
44 return old_value;
45 }
46
47 __ATOMIC_INLINE__ int32_t
__bionic_atomic_inc(volatile int32_t * ptr)48 __bionic_atomic_inc(volatile int32_t* ptr)
49 {
50 /* We must return the old value */
51 return __sync_fetch_and_add(ptr, 1);
52 }
53
54 __ATOMIC_INLINE__ int32_t
__bionic_atomic_dec(volatile int32_t * ptr)55 __bionic_atomic_dec(volatile int32_t* ptr)
56 {
57 /* We must return the old value */
58 return __sync_fetch_and_add(ptr, -1);
59 }
60
61 #endif /* BIONIC_ATOMIC_GCC_BUILTIN_H */
62