335 lines
8.7 KiB
C
335 lines
8.7 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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#if defined(HAVE_MACOSX_IPC)
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#include <libkern/OSAtomic.h>
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void android_atomic_write(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 (OSAtomicCompareAndSwap32Barrier(oldValue, value, (int32_t*)addr) == 0);
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}
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int32_t android_atomic_inc(volatile int32_t* addr) {
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return OSAtomicIncrement32Barrier((int32_t*)addr)-1;
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}
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int32_t android_atomic_dec(volatile int32_t* addr) {
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return OSAtomicDecrement32Barrier((int32_t*)addr)+1;
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}
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int32_t android_atomic_add(int32_t value, volatile int32_t* addr) {
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return OSAtomicAdd32Barrier(value, (int32_t*)addr)-value;
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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 (OSAtomicCompareAndSwap32Barrier(oldValue, oldValue&value, (int32_t*)addr) == 0);
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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 (OSAtomicCompareAndSwap32Barrier(oldValue, oldValue|value, (int32_t*)addr) == 0);
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return oldValue;
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}
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int32_t android_atomic_swap(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_cmpxchg(oldValue, value, addr));
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return oldValue;
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}
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int android_atomic_cmpxchg(int32_t oldvalue, int32_t newvalue, volatile int32_t* addr) {
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return OSAtomicCompareAndSwap32Barrier(oldvalue, newvalue, (int32_t*)addr) == 0;
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}
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#if defined(__ppc__) \
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|| defined(__PPC__) \
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|| defined(__powerpc__) \
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|| defined(__powerpc) \
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|| defined(__POWERPC__) \
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|| defined(_M_PPC) \
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|| defined(__PPC)
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#define NEED_QUASIATOMICS 1
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#else
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int android_quasiatomic_cmpxchg_64(int64_t oldvalue, int64_t newvalue,
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volatile int64_t* addr) {
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return OSAtomicCompareAndSwap64Barrier(oldvalue, newvalue,
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(int64_t*)addr) == 0;
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}
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int64_t android_quasiatomic_swap_64(int64_t value, volatile int64_t* addr) {
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int64_t oldValue;
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do {
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oldValue = *addr;
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} while (android_quasiatomic_cmpxchg_64(oldValue, value, addr));
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return oldValue;
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}
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int64_t android_quasiatomic_read_64(volatile int64_t* addr) {
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return OSAtomicAdd64Barrier(0, addr);
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}
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#endif
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/*****************************************************************************/
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#elif defined(__i386__) || defined(__x86_64__)
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void android_atomic_write(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_cmpxchg(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_cmpxchg(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_cmpxchg(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_cmpxchg(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_cmpxchg(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_cmpxchg(oldValue, oldValue|value, addr));
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return oldValue;
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}
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int32_t android_atomic_swap(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_cmpxchg(oldValue, value, addr));
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return oldValue;
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}
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int android_atomic_cmpxchg(int32_t oldvalue, int32_t newvalue, volatile int32_t* addr) {
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int xchg;
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asm volatile
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(
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" lock; cmpxchg %%ecx, (%%edx);"
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" setne %%al;"
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" andl $1, %%eax"
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: "=a" (xchg)
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: "a" (oldvalue), "c" (newvalue), "d" (addr)
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);
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return xchg;
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}
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#define NEED_QUASIATOMICS 1
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/*****************************************************************************/
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#elif __arm__
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// Most of the implementation is in atomic-android-arm.s.
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// on the device, we implement the 64-bit atomic operations through
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// mutex locking. normally, this is bad because we must initialize
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// a pthread_mutex_t before being able to use it, and this means
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// having to do an initialization check on each function call, and
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// that's where really ugly things begin...
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//
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// BUT, as a special twist, we take advantage of the fact that in our
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// pthread library, a mutex is simply a volatile word whose value is always
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// initialized to 0. In other words, simply declaring a static mutex
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// object initializes it !
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//
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// another twist is that we use a small array of mutexes to dispatch
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// the contention locks from different memory addresses
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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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int64_t android_quasiatomic_swap_64(int64_t value, volatile int64_t* addr) {
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int64_t oldValue;
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pthread_mutex_t* lock = SWAP_LOCK(addr);
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pthread_mutex_lock(lock);
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oldValue = *addr;
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*addr = value;
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pthread_mutex_unlock(lock);
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return oldValue;
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}
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int android_quasiatomic_cmpxchg_64(int64_t oldvalue, int64_t newvalue,
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volatile int64_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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int64_t android_quasiatomic_read_64(volatile int64_t* addr) {
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int64_t result;
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pthread_mutex_t* lock = SWAP_LOCK(addr);
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pthread_mutex_lock(lock);
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result = *addr;
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pthread_mutex_unlock(lock);
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return result;
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}
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#else
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#error "Unsupported atomic operations for this platform"
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#endif
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#if NEED_QUASIATOMICS
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/* Note that a spinlock is *not* a good idea in general
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* since they can introduce subtle issues. For example,
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* a real-time thread trying to acquire a spinlock already
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* acquired by another thread will never yeld, making the
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* CPU loop endlessly!
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*
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* However, this code is only used on the Linux simulator
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* so it's probably ok for us.
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*
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* The alternative is to use a pthread mutex, but
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* these must be initialized before being used, and
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* then you have the problem of lazily initializing
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* a mutex without any other synchronization primitive.
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*/
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/* global spinlock for all 64-bit quasiatomic operations */
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static int32_t quasiatomic_spinlock = 0;
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int android_quasiatomic_cmpxchg_64(int64_t oldvalue, int64_t newvalue,
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volatile int64_t* addr) {
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int result;
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while (android_atomic_cmpxchg(0, 1, &quasiatomic_spinlock)) {
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#ifdef HAVE_WIN32_THREADS
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Sleep(0);
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#else
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sched_yield();
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#endif
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}
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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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android_atomic_swap(0, &quasiatomic_spinlock);
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return result;
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}
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int64_t android_quasiatomic_read_64(volatile int64_t* addr) {
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int64_t result;
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while (android_atomic_cmpxchg(0, 1, &quasiatomic_spinlock)) {
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#ifdef HAVE_WIN32_THREADS
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Sleep(0);
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#else
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sched_yield();
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#endif
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}
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result = *addr;
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android_atomic_swap(0, &quasiatomic_spinlock);
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return result;
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}
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int64_t android_quasiatomic_swap_64(int64_t value, volatile int64_t* addr) {
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int64_t result;
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while (android_atomic_cmpxchg(0, 1, &quasiatomic_spinlock)) {
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#ifdef HAVE_WIN32_THREADS
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Sleep(0);
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#else
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sched_yield();
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#endif
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}
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result = *addr;
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*addr = value;
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android_atomic_swap(0, &quasiatomic_spinlock);
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return result;
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}
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#endif
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