michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * vim: sw=2 ts=8 et :
michael@0:  */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: // This file is an internal atomic implementation, use
michael@0: // base/atomicops.h instead.
michael@0: //
michael@0: // This is a very slow fallback implementation of atomic operations
michael@0: // that uses a mutex instead of atomic instructions.
michael@0: //
michael@0: // (NB: a small "optimization" here would be using a spinlock instead
michael@0: // of a blocking mutex, but it's probably not worth the time.)
michael@0: 
michael@0: #ifndef base_atomicops_internals_mutex_h
michael@0: #define base_atomicops_internals_mutex_h
michael@0: 
michael@0: #include "base/lock.h"
michael@0: 
michael@0: namespace base {
michael@0: namespace subtle {
michael@0: 
michael@0: extern Lock gAtomicsMutex;
michael@0: 
michael@0: template<typename T>
michael@0: T Locked_CAS(volatile T* ptr, T old_value, T new_value) {
michael@0:   AutoLock _(gAtomicsMutex);
michael@0: 
michael@0:   T current_value = *ptr;
michael@0:   if (current_value == old_value)
michael@0:     *ptr = new_value;
michael@0:   
michael@0:   return current_value;
michael@0: }
michael@0: 
michael@0: template<typename T>
michael@0: T Locked_AtomicExchange(volatile T* ptr, T new_value) {
michael@0:   AutoLock _(gAtomicsMutex);
michael@0: 
michael@0:   T current_value = *ptr;
michael@0:   *ptr = new_value;
michael@0:   return current_value;
michael@0: }
michael@0: 
michael@0: template<typename T>
michael@0: T Locked_AtomicIncrement(volatile T* ptr, T increment) {
michael@0:   AutoLock _(gAtomicsMutex);
michael@0:   return *ptr += increment;
michael@0: }
michael@0: 
michael@0: template<typename T>
michael@0: void Locked_Store(volatile T* ptr, T value) {
michael@0:   AutoLock _(gAtomicsMutex);
michael@0:   *ptr = value;
michael@0: }
michael@0: 
michael@0: template<typename T>
michael@0: T Locked_Load(volatile const T* ptr) {
michael@0:   AutoLock _(gAtomicsMutex);
michael@0:   return *ptr;
michael@0: }
michael@0: 
michael@0: inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
michael@0:                                          Atomic32 old_value,
michael@0:                                          Atomic32 new_value) {
michael@0:   return Locked_CAS(ptr, old_value, new_value);
michael@0: }
michael@0: 
michael@0: inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
michael@0:                                          Atomic32 new_value) {
michael@0:   return Locked_AtomicExchange(ptr, new_value);
michael@0: }
michael@0: 
michael@0: inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
michael@0:                                           Atomic32 increment) {
michael@0:   return Locked_AtomicIncrement(ptr, increment);
michael@0: }
michael@0: 
michael@0: inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
michael@0:                                         Atomic32 increment) {
michael@0:   return Locked_AtomicIncrement(ptr, increment);
michael@0: }
michael@0: 
michael@0: inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
michael@0:                                        Atomic32 old_value,
michael@0:                                        Atomic32 new_value) {
michael@0:   return Locked_CAS(ptr, old_value, new_value);
michael@0: }
michael@0: 
michael@0: inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
michael@0:                                        Atomic32 old_value,
michael@0:                                        Atomic32 new_value) {
michael@0:   return Locked_CAS(ptr, old_value, new_value);
michael@0: }
michael@0: 
michael@0: inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
michael@0:   return Locked_Store(ptr, value);
michael@0: }
michael@0: 
michael@0: inline void MemoryBarrier() {
michael@0:   AutoLock _(gAtomicsMutex);
michael@0:   // lock/unlock work as a barrier here
michael@0: }
michael@0: 
michael@0: inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
michael@0:   return Locked_Store(ptr, value);
michael@0: }
michael@0: 
michael@0: inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
michael@0:   return Locked_Store(ptr, value);
michael@0: }
michael@0: 
michael@0: inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
michael@0:   return Locked_Load(ptr);
michael@0: }
michael@0: 
michael@0: inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
michael@0:   return NoBarrier_Load(ptr);
michael@0: }
michael@0: 
michael@0: inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
michael@0:   return Locked_Load(ptr);
michael@0: }
michael@0: 
michael@0: #ifdef ARCH_CPU_64_BITS
michael@0: 
michael@0: inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
michael@0:                                          Atomic64 old_value,
michael@0:                                          Atomic64 new_value) {
michael@0:   return Locked_CAS(ptr, old_value, new_value);
michael@0: }
michael@0: 
michael@0: inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
michael@0:                                          Atomic64 new_value) {
michael@0:   return Locked_AtomicExchange(ptr, new_value);
michael@0: }
michael@0: 
michael@0: inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
michael@0:                                           Atomic64 increment) {
michael@0:   return Locked_AtomicIncrement(ptr, increment);
michael@0: }
michael@0: 
michael@0: inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
michael@0:                                         Atomic64 increment) {
michael@0:   return Locked_AtomicIncrement(ptr, increment);
michael@0: }
michael@0: 
michael@0: inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
michael@0:   return Locked_Store(ptr, value);
michael@0: }
michael@0: 
michael@0: inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
michael@0:                                        Atomic64 old_value,
michael@0:                                        Atomic64 new_value) {
michael@0:   return Locked_CAS(ptr, old_value, new_value);
michael@0: }
michael@0: 
michael@0: inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
michael@0:   return Locked_Store(ptr, value);
michael@0: }
michael@0: 
michael@0: inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
michael@0:   return Locked_Store(ptr, value);
michael@0: }
michael@0: 
michael@0: inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
michael@0:   return Locked_Load(ptr);
michael@0: }
michael@0: 
michael@0: inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
michael@0:   return Locked_Load(ptr);
michael@0: }
michael@0: 
michael@0: inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
michael@0:   return Locked_Load(ptr);
michael@0: }
michael@0: 
michael@0: #endif  // ARCH_CPU_64_BITS
michael@0: 
michael@0: #ifdef OS_MACOSX
michael@0: // From atomicops_internals_x86_macosx.h:
michael@0: //
michael@0: //   MacOS uses long for intptr_t, AtomicWord and Atomic32 are always
michael@0: //   different on the Mac, even when they are the same size.  We need
michael@0: //   to explicitly cast from AtomicWord to Atomic32/64 to implement
michael@0: //   the AtomicWord interface.
michael@0: 
michael@0: inline AtomicWord NoBarrier_CompareAndSwap(volatile AtomicWord* ptr,
michael@0:                                            AtomicWord old_value,
michael@0:                                            AtomicWord new_value) {
michael@0:   return Locked_CAS(ptr, old_value, new_value);
michael@0: }
michael@0: 
michael@0: inline AtomicWord NoBarrier_AtomicExchange(volatile AtomicWord* ptr,
michael@0:                                            AtomicWord new_value) {
michael@0:   return Locked_AtomicExchange(ptr, new_value);
michael@0: }
michael@0: 
michael@0: inline AtomicWord NoBarrier_AtomicIncrement(volatile AtomicWord* ptr,
michael@0:                                             AtomicWord increment) {
michael@0:   return Locked_AtomicIncrement(ptr, increment);
michael@0: }
michael@0: 
michael@0: inline AtomicWord Barrier_AtomicIncrement(volatile AtomicWord* ptr,
michael@0:                                           AtomicWord increment) {
michael@0:   return Locked_AtomicIncrement(ptr, increment);
michael@0: }
michael@0: 
michael@0: inline AtomicWord Acquire_CompareAndSwap(volatile AtomicWord* ptr,
michael@0:                                          AtomicWord old_value,
michael@0:                                          AtomicWord new_value) {
michael@0:   return Locked_CAS(ptr, old_value, new_value);
michael@0: }
michael@0: 
michael@0: inline AtomicWord Release_CompareAndSwap(volatile AtomicWord* ptr,
michael@0:                                          AtomicWord old_value,
michael@0:                                          AtomicWord new_value) {
michael@0:   return Locked_CAS(ptr, old_value, new_value);
michael@0: }
michael@0: 
michael@0: inline void NoBarrier_Store(volatile AtomicWord *ptr, AtomicWord value) {
michael@0:   return Locked_Store(ptr, value);
michael@0: }
michael@0: 
michael@0: inline void Acquire_Store(volatile AtomicWord* ptr, AtomicWord value) {
michael@0:   return Locked_Store(ptr, value);
michael@0: }
michael@0: 
michael@0: inline void Release_Store(volatile AtomicWord* ptr, AtomicWord value) {
michael@0:   return Locked_Store(ptr, value);
michael@0: }
michael@0: 
michael@0: inline AtomicWord NoBarrier_Load(volatile const AtomicWord *ptr) {
michael@0:   return Locked_Load(ptr);
michael@0: }
michael@0: 
michael@0: inline AtomicWord Acquire_Load(volatile const AtomicWord* ptr) {
michael@0:   return Locked_Load(ptr);
michael@0: }
michael@0: 
michael@0: inline AtomicWord Release_Load(volatile const AtomicWord* ptr) {
michael@0:   return Locked_Load(ptr);
michael@0: }
michael@0: 
michael@0: #endif  // OS_MACOSX
michael@0: 
michael@0: }  // namespace subtle
michael@0: }  // namespace base
michael@0: 
michael@0: #endif  // base_atomicops_internals_mutex_h