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+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+/* Copyright (c) 2006, Google Inc.
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// Implementation of atomic operations for Mac OS X.  This file should not
+// be included directly.  Clients should instead include
+// "base/atomicops.h".
+
+#ifndef BASE_ATOMICOPS_INTERNALS_MACOSX_H_
+#define BASE_ATOMICOPS_INTERNALS_MACOSX_H_
+
+typedef int32_t Atomic32;
+
+// MacOS uses long for intptr_t, AtomicWord and Atomic32 are always different
+// on the Mac, even when they are the same size.  Similarly, on __ppc64__,
+// AtomicWord and Atomic64 are always different.  Thus, we need explicit
+// casting.
+#ifdef __LP64__
+#define AtomicWordCastType base::subtle::Atomic64
+#else
+#define AtomicWordCastType Atomic32
+#endif
+
+#if defined(__LP64__) || defined(__i386__)
+#define BASE_HAS_ATOMIC64 1  // Use only in tests and base/atomic*
+#endif
+
+#include <libkern/OSAtomic.h>
+
+namespace base {
+namespace subtle {
+
+#if !defined(__LP64__) && defined(__ppc__)
+
+// The Mac 64-bit OSAtomic implementations are not available for 32-bit PowerPC,
+// while the underlying assembly instructions are available only some
+// implementations of PowerPC.
+
+// The following inline functions will fail with the error message at compile
+// time ONLY IF they are called.  So it is safe to use this header if user
+// code only calls AtomicWord and Atomic32 operations.
+//
+// NOTE(vchen): Implementation notes to implement the atomic ops below may
+// be found in "PowerPC Virtual Environment Architecture, Book II,
+// Version 2.02", January 28, 2005, Appendix B, page 46.  Unfortunately,
+// extra care must be taken to ensure data are properly 8-byte aligned, and
+// that data are returned correctly according to Mac OS X ABI specs.
+
+inline int64_t OSAtomicCompareAndSwap64(
+    int64_t oldValue, int64_t newValue, int64_t *theValue) {
+  __asm__ __volatile__(
+      "_OSAtomicCompareAndSwap64_not_supported_for_32_bit_ppc\n\t");
+  return 0;
+}
+
+inline int64_t OSAtomicAdd64(int64_t theAmount, int64_t *theValue) {
+  __asm__ __volatile__(
+      "_OSAtomicAdd64_not_supported_for_32_bit_ppc\n\t");
+  return 0;
+}
+
+inline int64_t OSAtomicCompareAndSwap64Barrier(
+    int64_t oldValue, int64_t newValue, int64_t *theValue) {
+  int64_t prev = OSAtomicCompareAndSwap64(oldValue, newValue, theValue);
+  OSMemoryBarrier();
+  return prev;
+}
+
+inline int64_t OSAtomicAdd64Barrier(
+    int64_t theAmount, int64_t *theValue) {
+  int64_t new_val = OSAtomicAdd64(theAmount, theValue);
+  OSMemoryBarrier();
+  return new_val;
+}
+#endif
+
+typedef int64_t Atomic64;
+
+inline void MemoryBarrier() {
+  OSMemoryBarrier();
+}
+
+// 32-bit Versions.
+
+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 Acquire_AtomicExchange(volatile Atomic32 *ptr,
+                                       Atomic32 new_value) {
+  Atomic32 old_value;
+  do {
+    old_value = *ptr;
+  } while (!OSAtomicCompareAndSwap32Barrier(old_value, new_value,
+                                            const_cast<Atomic32*>(ptr)));
+  return old_value;
+}
+
+inline Atomic32 Release_AtomicExchange(volatile Atomic32 *ptr,
+                                       Atomic32 new_value) {
+  return Acquire_AtomicExchange(ptr, new_value);
+}
+
+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;
+}
+
+// 64-bit version
+
+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 Acquire_AtomicExchange(volatile Atomic64 *ptr,
+                                       Atomic64 new_value) {
+  Atomic64 old_value;
+  do {
+    old_value = *ptr;
+  } while (!OSAtomicCompareAndSwap64Barrier(old_value, new_value,
+                                            const_cast<Atomic64*>(ptr)));
+  return old_value;
+}
+
+inline Atomic64 Release_AtomicExchange(volatile Atomic64 *ptr,
+                                       Atomic64 new_value) {
+  return Acquire_AtomicExchange(ptr, new_value);
+}
+
+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);
+}
+
+#ifdef __LP64__
+
+// 64-bit implementation on 64-bit platform
+
+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;
+}
+
+#else
+
+// 64-bit implementation on 32-bit platform
+
+#if defined(__ppc__)
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+   __asm__ __volatile__(
+       "_NoBarrier_Store_not_supported_for_32_bit_ppc\n\t");
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+   __asm__ __volatile__(
+       "_NoBarrier_Load_not_supported_for_32_bit_ppc\n\t");
+   return 0;
+}
+
+#elif defined(__i386__)
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+  __asm__ __volatile__("movq %1, %%mm0\n\t"    // Use mmx reg for 64-bit atomic
+                       "movq %%mm0, %0\n\t"  // moves (ptr could be read-only)
+                       "emms\n\t"              // Reset FP registers
+                       : "=m" (*ptr)
+                       : "m" (value)
+                       : // mark the FP stack and mmx registers as clobbered
+                         "st", "st(1)", "st(2)", "st(3)", "st(4)",
+                         "st(5)", "st(6)", "st(7)", "mm0", "mm1",
+                         "mm2", "mm3", "mm4", "mm5", "mm6", "mm7");
+
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+  Atomic64 value;
+  __asm__ __volatile__("movq %1, %%mm0\n\t"  // Use mmx reg for 64-bit atomic
+                       "movq %%mm0, %0\n\t"  // moves (ptr could be read-only)
+                       "emms\n\t"            // Reset FP registers
+                       : "=m" (value)
+                       : "m" (*ptr)
+                       : // mark the FP stack and mmx registers as clobbered
+                         "st", "st(1)", "st(2)", "st(3)", "st(4)",
+                         "st(5)", "st(6)", "st(7)", "mm0", "mm1",
+                         "mm2", "mm3", "mm4", "mm5", "mm6", "mm7");
+
+  return value;
+}
+#endif
+
+
+inline void Acquire_Store(volatile Atomic64 *ptr, Atomic64 value) {
+  NoBarrier_Store(ptr, value);
+  MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic64 *ptr, Atomic64 value) {
+  MemoryBarrier();
+  NoBarrier_Store(ptr, value);
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64 *ptr) {
+  Atomic64 value = NoBarrier_Load(ptr);
+  MemoryBarrier();
+  return value;
+}
+
+inline Atomic64 Release_Load(volatile const Atomic64 *ptr) {
+  MemoryBarrier();
+  return NoBarrier_Load(ptr);
+}
+#endif  // __LP64__
+
+}   // namespace base::subtle
+}   // namespace base
+
+#endif  // BASE_ATOMICOPS_INTERNALS_MACOSX_H_