base/atomicops_internals_x86_macosx.h

// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file is an internal atomic implementation, use base/atomicops.h instead.

#ifndef BASE_ATOMICOPS_INTERNALS_X86_MACOSX_H_
#define BASE_ATOMICOPS_INTERNALS_X86_MACOSX_H_

#include <libkern/OSAtomic.h>

namespace base {
namespace subtle {

inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32 *ptr,
                                         Atomic32 old_value,
                                         Atomic32 new_value) {
  Atomic32 prev_value;
  do {
    if (OSAtomicCompareAndSwap32(old_value, new_value,
                                 const_cast<Atomic32*>(ptr))) {
      return old_value;
    }
    prev_value = *ptr;
  } while (prev_value == old_value);
  return prev_value;
}

inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32 *ptr,
                                         Atomic32 new_value) {
  Atomic32 old_value;
  do {
    old_value = *ptr;
  } while (!OSAtomicCompareAndSwap32(old_value, new_value,
                                     const_cast<Atomic32*>(ptr)));
  return old_value;
}

inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32 *ptr,
                                          Atomic32 increment) {
  return OSAtomicAdd32(increment, const_cast<Atomic32*>(ptr));
}

inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32 *ptr,
                                          Atomic32 increment) {
  return OSAtomicAdd32Barrier(increment, const_cast<Atomic32*>(ptr));
}

inline void MemoryBarrier() {
  OSMemoryBarrier();
}

inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32 *ptr,
                                       Atomic32 old_value,
                                       Atomic32 new_value) {
  Atomic32 prev_value;
  do {
    if (OSAtomicCompareAndSwap32Barrier(old_value, new_value,
                                        const_cast<Atomic32*>(ptr))) {
      return old_value;
    }
    prev_value = *ptr;
  } while (prev_value == old_value);
  return prev_value;
}

inline Atomic32 Release_CompareAndSwap(volatile Atomic32 *ptr,
                                       Atomic32 old_value,
                                       Atomic32 new_value) {
  return Acquire_CompareAndSwap(ptr, old_value, new_value);
}

inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
  *ptr = value;
}

inline void Acquire_Store(volatile Atomic32 *ptr, Atomic32 value) {
  *ptr = value;
  MemoryBarrier();
}

inline void Release_Store(volatile Atomic32 *ptr, Atomic32 value) {
  MemoryBarrier();
  *ptr = value;
}

inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
  return *ptr;
}

inline Atomic32 Acquire_Load(volatile const Atomic32 *ptr) {
  Atomic32 value = *ptr;
  MemoryBarrier();
  return value;
}

inline Atomic32 Release_Load(volatile const Atomic32 *ptr) {
  MemoryBarrier();
  return *ptr;
}

#ifdef __LP64__

// 64-bit implementation on 64-bit platform

inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64 *ptr,
                                         Atomic64 old_value,
                                         Atomic64 new_value) {
  Atomic64 prev_value;
  do {
    if (OSAtomicCompareAndSwap64(old_value, new_value,
                                 const_cast<Atomic64*>(ptr))) {
      return old_value;
    }
    prev_value = *ptr;
  } while (prev_value == old_value);
  return prev_value;
}

inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64 *ptr,
                                         Atomic64 new_value) {
  Atomic64 old_value;
  do {
    old_value = *ptr;
  } while (!OSAtomicCompareAndSwap64(old_value, new_value,
                                     const_cast<Atomic64*>(ptr)));
  return old_value;
}

inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64 *ptr,
                                          Atomic64 increment) {
  return OSAtomicAdd64(increment, const_cast<Atomic64*>(ptr));
}

inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64 *ptr,
                                        Atomic64 increment) {
  return OSAtomicAdd64Barrier(increment, const_cast<Atomic64*>(ptr));
}

inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64 *ptr,
                                       Atomic64 old_value,
                                       Atomic64 new_value) {
  Atomic64 prev_value;
  do {
    if (OSAtomicCompareAndSwap64Barrier(old_value, new_value,
                                        const_cast<Atomic64*>(ptr))) {
      return old_value;
    }
    prev_value = *ptr;
  } while (prev_value == old_value);
  return prev_value;
}

inline Atomic64 Release_CompareAndSwap(volatile Atomic64 *ptr,
                                       Atomic64 old_value,
                                       Atomic64 new_value) {
  // The lib kern interface does not distinguish between
  // Acquire and Release memory barriers; they are equivalent.
  return Acquire_CompareAndSwap(ptr, old_value, new_value);
}

inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
  *ptr = value;
}

inline void Acquire_Store(volatile Atomic64 *ptr, Atomic64 value) {
  *ptr = value;
  MemoryBarrier();
}

inline void Release_Store(volatile Atomic64 *ptr, Atomic64 value) {
  MemoryBarrier();
  *ptr = value;
}

inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
  return *ptr;
}

inline Atomic64 Acquire_Load(volatile const Atomic64 *ptr) {
  Atomic64 value = *ptr;
  MemoryBarrier();
  return value;
}

inline Atomic64 Release_Load(volatile const Atomic64 *ptr) {
  MemoryBarrier();
  return *ptr;
}

#endif  // defined(__LP64__)

// MacOS uses long for intptr_t, AtomicWord and Atomic32 are always different
// on the Mac, even when they are the same size.  We need to explicitly cast
// from AtomicWord to Atomic32/64 to implement the AtomicWord interface.
#ifdef __LP64__
#define AtomicWordCastType Atomic64
#else
#define AtomicWordCastType Atomic32
#endif

inline AtomicWord NoBarrier_CompareAndSwap(volatile AtomicWord* ptr,
                                           AtomicWord old_value,
                                           AtomicWord new_value) {
  return NoBarrier_CompareAndSwap(
      reinterpret_cast<volatile AtomicWordCastType*>(ptr),
      old_value, new_value);
}

inline AtomicWord NoBarrier_AtomicExchange(volatile AtomicWord* ptr,
                                           AtomicWord new_value) {
  return NoBarrier_AtomicExchange(
      reinterpret_cast<volatile AtomicWordCastType*>(ptr), new_value);
}

inline AtomicWord NoBarrier_AtomicIncrement(volatile AtomicWord* ptr,
                                            AtomicWord increment) {
  return NoBarrier_AtomicIncrement(
      reinterpret_cast<volatile AtomicWordCastType*>(ptr), increment);
}

inline AtomicWord Barrier_AtomicIncrement(volatile AtomicWord* ptr,
                                          AtomicWord increment) {
  return Barrier_AtomicIncrement(
      reinterpret_cast<volatile AtomicWordCastType*>(ptr), increment);
}

inline AtomicWord Acquire_CompareAndSwap(volatile AtomicWord* ptr,
                                         AtomicWord old_value,
                                         AtomicWord new_value) {
  return base::subtle::Acquire_CompareAndSwap(
      reinterpret_cast<volatile AtomicWordCastType*>(ptr),
      old_value, new_value);
}

inline AtomicWord Release_CompareAndSwap(volatile AtomicWord* ptr,
                                         AtomicWord old_value,
                                         AtomicWord new_value) {
  return base::subtle::Release_CompareAndSwap(
      reinterpret_cast<volatile AtomicWordCastType*>(ptr),
      old_value, new_value);
}

inline void NoBarrier_Store(volatile AtomicWord *ptr, AtomicWord value) {
  NoBarrier_Store(
      reinterpret_cast<volatile AtomicWordCastType*>(ptr), value);
}

inline void Acquire_Store(volatile AtomicWord* ptr, AtomicWord value) {
  return base::subtle::Acquire_Store(
      reinterpret_cast<volatile AtomicWordCastType*>(ptr), value);
}

inline void Release_Store(volatile AtomicWord* ptr, AtomicWord value) {
  return base::subtle::Release_Store(
      reinterpret_cast<volatile AtomicWordCastType*>(ptr), value);
}

inline AtomicWord NoBarrier_Load(volatile const AtomicWord *ptr) {
  return NoBarrier_Load(
      reinterpret_cast<volatile const AtomicWordCastType*>(ptr));
}

inline AtomicWord Acquire_Load(volatile const AtomicWord* ptr) {
  return base::subtle::Acquire_Load(
      reinterpret_cast<volatile const AtomicWordCastType*>(ptr));
}

inline AtomicWord Release_Load(volatile const AtomicWord* ptr) {
  return base::subtle::Release_Load(
      reinterpret_cast<volatile const AtomicWordCastType*>(ptr));
}

#undef AtomicWordCastType

}   // namespace base::subtle
}   // namespace base

#endif  // BASE_ATOMICOPS_INTERNALS_X86_MACOSX_H_