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/*
20 * This header file is used by default if we don't have optimized atomic
21 * routines for a given platform. See bionic_atomic_arm.h and
22 * bionic_atomic_x86.h for examples.
23 *
24 * Note that the GCC builtins include barriers that aren't present in
25 * the architecture-specific assembler versions.
26 */
27
28__ATOMIC_INLINE__ void __bionic_memory_barrier() {
29  __sync_synchronize();
30}
31
32__ATOMIC_INLINE__ int __bionic_cmpxchg(int32_t old_value, int32_t new_value, volatile int32_t* ptr) {
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  int32_t old_value;
39  do {
40    old_value = *ptr;
41  } while (__sync_val_compare_and_swap(ptr, old_value, new_value) != old_value);
42  return old_value;
43}
44
45__ATOMIC_INLINE__ int32_t __bionic_atomic_dec(volatile int32_t* ptr) {
46  /* We must return the old value. */
47  return __sync_fetch_and_add(ptr, -1);
48}
49
50#endif /* BIONIC_ATOMIC_GCC_BUILTIN_H */
51