michael@0: /*
michael@0:  * Copyright (C) 2007 The Android Open Source Project
michael@0:  *
michael@0:  * Licensed under the Apache License, Version 2.0 (the "License");
michael@0:  * you may not use this file except in compliance with the License.
michael@0:  * You may obtain a copy of the License at
michael@0:  *
michael@0:  *      http://www.apache.org/licenses/LICENSE-2.0
michael@0:  *
michael@0:  * Unless required by applicable law or agreed to in writing, software
michael@0:  * distributed under the License is distributed on an "AS IS" BASIS,
michael@0:  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
michael@0:  * See the License for the specific language governing permissions and
michael@0:  * limitations under the License.
michael@0:  */
michael@0: 
michael@0: #ifndef ANDROID_CUTILS_ATOMIC_H
michael@0: #define ANDROID_CUTILS_ATOMIC_H
michael@0: 
michael@0: #include <stdint.h>
michael@0: #include <sys/types.h>
michael@0: 
michael@0: #ifdef __cplusplus
michael@0: extern "C" {
michael@0: #endif
michael@0: 
michael@0: /*
michael@0:  * NOTE: memory shared between threads is synchronized by all atomic operations
michael@0:  * below, this means that no explicit memory barrier is required: all reads or 
michael@0:  * writes issued before android_atomic_* operations are guaranteed to complete
michael@0:  * before the atomic operation takes place.
michael@0:  */
michael@0: 
michael@0: void android_atomic_write(int32_t value, volatile int32_t* addr);
michael@0: 
michael@0: /*
michael@0:  * all these atomic operations return the previous value
michael@0:  */
michael@0: 
michael@0: 
michael@0: int32_t android_atomic_inc(volatile int32_t* addr);
michael@0: int32_t android_atomic_dec(volatile int32_t* addr);
michael@0: 
michael@0: int32_t android_atomic_add(int32_t value, volatile int32_t* addr);
michael@0: int32_t android_atomic_and(int32_t value, volatile int32_t* addr);
michael@0: int32_t android_atomic_or(int32_t value, volatile int32_t* addr);
michael@0: 
michael@0: int32_t android_atomic_swap(int32_t value, volatile int32_t* addr);
michael@0: 
michael@0: /*
michael@0:  * NOTE: Two "quasiatomic" operations on the exact same memory address
michael@0:  * are guaranteed to operate atomically with respect to each other,
michael@0:  * but no guarantees are made about quasiatomic operations mixed with
michael@0:  * non-quasiatomic operations on the same address, nor about
michael@0:  * quasiatomic operations that are performed on partially-overlapping
michael@0:  * memory.
michael@0:  */
michael@0: 
michael@0: int64_t android_quasiatomic_swap_64(int64_t value, volatile int64_t* addr);
michael@0: int64_t android_quasiatomic_read_64(volatile int64_t* addr);
michael@0:     
michael@0: /*
michael@0:  * cmpxchg return a non zero value if the exchange was NOT performed,
michael@0:  * in other words if oldvalue != *addr
michael@0:  */
michael@0: 
michael@0: int android_atomic_cmpxchg(int32_t oldvalue, int32_t newvalue,
michael@0:         volatile int32_t* addr);
michael@0: 
michael@0: int android_quasiatomic_cmpxchg_64(int64_t oldvalue, int64_t newvalue,
michael@0:         volatile int64_t* addr);
michael@0: 
michael@0: 
michael@0:     
michael@0: #ifdef __cplusplus
michael@0: } // extern "C"
michael@0: #endif
michael@0: 
michael@0: #endif // ANDROID_CUTILS_ATOMIC_H