137 lines
3.8 KiB
C
137 lines
3.8 KiB
C
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <cutils/atomic.h>
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#ifdef HAVE_WIN32_THREADS
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#include <windows.h>
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#else
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#include <sched.h>
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#endif
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/*
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* Note :
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*
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* (1) SuperH does not have CMPXCHG. It has only TAS for atomic
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* operations. It does not seem a good idea to implement CMPXCHG,
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* with TAS. So, we choose to implemnt these operations with
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* posix mutexes. Please be sure that this might cause performance
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* problem for Android-SH. Using LL/SC instructions supported in SH-X3,
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* best performnace would be realized.
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*
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* (2) Mutex initialization problem happens, which is commented for
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* ARM implementation, in this file above.
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* We follow the fact that the initializer for mutex is a simple zero
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* value.
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*
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* (3) These operations are NOT safe for SMP, as there is no currently
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* no definition for a memory barrier operation.
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*/
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#include <pthread.h>
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#define SWAP_LOCK_COUNT 32U
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static pthread_mutex_t _swap_locks[SWAP_LOCK_COUNT];
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#define SWAP_LOCK(addr) \
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&_swap_locks[((unsigned)(void*)(addr) >> 3U) % SWAP_LOCK_COUNT]
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int32_t android_atomic_acquire_load(volatile const int32_t* addr)
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{
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return *addr;
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}
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int32_t android_atomic_release_load(volatile const int32_t* addr)
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{
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return *addr;
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}
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void android_atomic_acquire_store(int32_t value, volatile int32_t* addr) {
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int32_t oldValue;
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do {
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oldValue = *addr;
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} while (android_atomic_release_cas(oldValue, value, addr));
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}
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void android_atomic_release_store(int32_t value, volatile int32_t* addr) {
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int32_t oldValue;
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do {
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oldValue = *addr;
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} while (android_atomic_release_cas(oldValue, value, addr));
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}
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int32_t android_atomic_inc(volatile int32_t* addr) {
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int32_t oldValue;
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do {
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oldValue = *addr;
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} while (android_atomic_release_cas(oldValue, oldValue+1, addr));
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return oldValue;
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}
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int32_t android_atomic_dec(volatile int32_t* addr) {
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int32_t oldValue;
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do {
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oldValue = *addr;
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} while (android_atomic_release_cas(oldValue, oldValue-1, addr));
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return oldValue;
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}
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int32_t android_atomic_add(int32_t value, volatile int32_t* addr) {
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int32_t oldValue;
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do {
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oldValue = *addr;
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} while (android_atomic_release_cas(oldValue, oldValue+value, addr));
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return oldValue;
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}
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int32_t android_atomic_and(int32_t value, volatile int32_t* addr) {
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int32_t oldValue;
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do {
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oldValue = *addr;
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} while (android_atomic_release_cas(oldValue, oldValue&value, addr));
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return oldValue;
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}
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int32_t android_atomic_or(int32_t value, volatile int32_t* addr) {
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int32_t oldValue;
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do {
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oldValue = *addr;
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} while (android_atomic_release_cas(oldValue, oldValue|value, addr));
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return oldValue;
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}
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int android_atomic_acquire_cmpxchg(int32_t oldvalue, int32_t newvalue,
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volatile int32_t* addr) {
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return android_atomic_release_cmpxchg(oldValue, newValue, addr);
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}
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int android_atomic_release_cmpxchg(int32_t oldvalue, int32_t newvalue,
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volatile int32_t* addr) {
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int result;
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pthread_mutex_t* lock = SWAP_LOCK(addr);
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pthread_mutex_lock(lock);
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if (*addr == oldvalue) {
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*addr = newvalue;
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result = 0;
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} else {
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result = 1;
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}
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pthread_mutex_unlock(lock);
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return result;
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}
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