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/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ANDROID_CUTILS_ATOMIC_H
#define ANDROID_CUTILS_ATOMIC_H
#include <stdint.h>
#include <sys/types.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
* Unless otherwise noted, the operations below perform a full fence before
* the atomic operation on SMP systems ("release" semantics).
*/
void android_atomic_write(int32_t value, volatile int32_t* addr);
/*
* all these atomic operations return the previous value
*/
int32_t android_atomic_inc(volatile int32_t* addr);
int32_t android_atomic_dec(volatile int32_t* addr);
int32_t android_atomic_add(int32_t value, volatile int32_t* addr);
int32_t android_atomic_and(int32_t value, volatile int32_t* addr);
int32_t android_atomic_or(int32_t value, volatile int32_t* addr);
int32_t android_atomic_swap(int32_t value, volatile int32_t* addr);
/*
* cmpxchg returns zero if the new value was successfully written. This
* will only happen when *addr == oldvalue.
*
* (The return value is inverted from implementations on other platforms, but
* matches the ARM ldrex/strex sematics. Note also this is a compare-and-set
* operation, not a compare-and-exchange operation, since we don't return
* the original value.)
*/
int android_atomic_cmpxchg(int32_t oldvalue, int32_t newvalue,
volatile int32_t* addr);
/*
* Same basic operation as android_atomic_cmpxchg, but with "acquire"
* semantics. The memory barrier, if required, is performed after the
* new value is stored. Useful for acquiring a spin lock.
*/
int android_atomic_acquire_cmpxchg(int32_t oldvalue, int32_t newvalue,
volatile int32_t* addr);
/*
* Perform an atomic store with "release" semantics. The memory barrier,
* if required, is performed before the store instruction. Useful for
* releasing a spin lock.
*/
#define android_atomic_release_store android_atomic_write
#ifdef __cplusplus
} // extern "C"
#endif
#endif // ANDROID_CUTILS_ATOMIC_H
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