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
