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// 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_