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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.
*/
#include <cutils/atomic.h>
#ifdef HAVE_WIN32_THREADS
#include <windows.h>
#else
#include <sched.h>
#endif
/*
* Note :
*
* (1) SuperH does not have CMPXCHG. It has only TAS for atomic
* operations. It does not seem a good idea to implement CMPXCHG,
* with TAS. So, we choose to implemnt these operations with
* posix mutexes. Please be sure that this might cause performance
* problem for Android-SH. Using LL/SC instructions supported in SH-X3,
* best performnace would be realized.
*
* (2) Mutex initialization problem happens, which is commented for
* ARM implementation, in this file above.
* We follow the fact that the initializer for mutex is a simple zero
* value.
*
* (3) These operations are NOT safe for SMP, as there is no currently
* no definition for a memory barrier operation.
*/
#include <pthread.h>
#define SWAP_LOCK_COUNT 32U
static pthread_mutex_t _swap_locks[SWAP_LOCK_COUNT];
#define SWAP_LOCK(addr) \
&_swap_locks[((unsigned)(void*)(addr) >> 3U) % SWAP_LOCK_COUNT]
int32_t android_atomic_acquire_load(volatile const int32_t* addr)
{
return *addr;
}
int32_t android_atomic_release_load(volatile const int32_t* addr)
{
return *addr;
}
void android_atomic_acquire_store(int32_t value, volatile int32_t* addr) {
int32_t oldValue;
do {
oldValue = *addr;
} while (android_atomic_release_cas(oldValue, value, addr));
}
void android_atomic_release_store(int32_t value, volatile int32_t* addr) {
int32_t oldValue;
do {
oldValue = *addr;
} while (android_atomic_release_cas(oldValue, value, addr));
}
int32_t android_atomic_inc(volatile int32_t* addr) {
int32_t oldValue;
do {
oldValue = *addr;
} while (android_atomic_release_cas(oldValue, oldValue+1, addr));
return oldValue;
}
int32_t android_atomic_dec(volatile int32_t* addr) {
int32_t oldValue;
do {
oldValue = *addr;
} while (android_atomic_release_cas(oldValue, oldValue-1, addr));
return oldValue;
}
int32_t android_atomic_add(int32_t value, volatile int32_t* addr) {
int32_t oldValue;
do {
oldValue = *addr;
} while (android_atomic_release_cas(oldValue, oldValue+value, addr));
return oldValue;
}
int32_t android_atomic_and(int32_t value, volatile int32_t* addr) {
int32_t oldValue;
do {
oldValue = *addr;
} while (android_atomic_release_cas(oldValue, oldValue&value, addr));
return oldValue;
}
int32_t android_atomic_or(int32_t value, volatile int32_t* addr) {
int32_t oldValue;
do {
oldValue = *addr;
} while (android_atomic_release_cas(oldValue, oldValue|value, addr));
return oldValue;
}
int android_atomic_acquire_cmpxchg(int32_t oldvalue, int32_t newvalue,
volatile int32_t* addr) {
return android_atomic_release_cmpxchg(oldValue, newValue, addr);
}
int android_atomic_release_cmpxchg(int32_t oldvalue, int32_t newvalue,
volatile int32_t* addr) {
int result;
pthread_mutex_t* lock = SWAP_LOCK(addr);
pthread_mutex_lock(lock);
if (*addr == oldvalue) {
*addr = newvalue;
result = 0;
} else {
result = 1;
}
pthread_mutex_unlock(lock);
return result;
}
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