michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef SkAtomics_win_DEFINED
michael@0: #define SkAtomics_win_DEFINED
michael@0: 
michael@0: /** Windows Interlocked atomics. */
michael@0: 
michael@0: #include <intrin.h>
michael@0: #include <stdint.h>
michael@0: 
michael@0: //MSDN says in order to declare an interlocked function for use as an
michael@0: //intrinsic, include intrin.h and put the function in a #pragma intrinsic
michael@0: //directive.
michael@0: //The pragma appears to be unnecessary, but doesn't hurt.
michael@0: #pragma intrinsic(_InterlockedIncrement, _InterlockedExchangeAdd, _InterlockedDecrement)
michael@0: #pragma intrinsic(_InterlockedCompareExchange)
michael@0: 
michael@0: static inline int32_t sk_atomic_inc(int32_t* addr) {
michael@0:     // InterlockedIncrement returns the new value, we want to return the old.
michael@0:     return _InterlockedIncrement(reinterpret_cast<long*>(addr)) - 1;
michael@0: }
michael@0: 
michael@0: static inline int32_t sk_atomic_add(int32_t* addr, int32_t inc) {
michael@0:     return _InterlockedExchangeAdd(reinterpret_cast<long*>(addr), static_cast<long>(inc));
michael@0: }
michael@0: 
michael@0: static inline int32_t sk_atomic_dec(int32_t* addr) {
michael@0:     // InterlockedDecrement returns the new value, we want to return the old.
michael@0:     return _InterlockedDecrement(reinterpret_cast<long*>(addr)) + 1;
michael@0: }
michael@0: 
michael@0: static inline void sk_membar_acquire__after_atomic_dec() { }
michael@0: 
michael@0: static inline int32_t sk_atomic_conditional_inc(int32_t* addr) {
michael@0:     long value = *addr;
michael@0:     while (true) {
michael@0:         if (value == 0) {
michael@0:             return 0;
michael@0:         }
michael@0: 
michael@0:         long before = _InterlockedCompareExchange(reinterpret_cast<long*>(addr), value + 1, value);
michael@0: 
michael@0:         if (before == value) {
michael@0:             return value;
michael@0:         } else {
michael@0:             value = before;
michael@0:         }
michael@0:     }
michael@0: }
michael@0: 
michael@0: static inline bool sk_atomic_cas(int32_t* addr, int32_t before, int32_t after) {
michael@0:     return _InterlockedCompareExchange(reinterpret_cast<long*>(addr), after, before) == before;
michael@0: }
michael@0: 
michael@0: static inline void sk_membar_acquire__after_atomic_conditional_inc() { }
michael@0: 
michael@0: #endif