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