bungeman@google.com | d9947f6 | 2013-12-18 15:27:39 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2013 Google Inc. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license that can be |
| 5 | * found in the LICENSE file. |
| 6 | */ |
| 7 | |
| 8 | #ifndef SkAtomics_win_DEFINED |
| 9 | #define SkAtomics_win_DEFINED |
| 10 | |
| 11 | /** Windows Interlocked atomics. */ |
| 12 | |
| 13 | #include <intrin.h> |
| 14 | #include <stdint.h> |
| 15 | |
| 16 | //MSDN says in order to declare an interlocked function for use as an |
| 17 | //intrinsic, include intrin.h and put the function in a #pragma intrinsic |
| 18 | //directive. |
| 19 | //The pragma appears to be unnecessary, but doesn't hurt. |
| 20 | #pragma intrinsic(_InterlockedIncrement, _InterlockedExchangeAdd, _InterlockedDecrement) |
| 21 | #pragma intrinsic(_InterlockedCompareExchange) |
| 22 | |
| 23 | static inline int32_t sk_atomic_inc(int32_t* addr) { |
| 24 | // InterlockedIncrement returns the new value, we want to return the old. |
| 25 | return _InterlockedIncrement(reinterpret_cast<long*>(addr)) - 1; |
| 26 | } |
| 27 | |
| 28 | static inline int32_t sk_atomic_add(int32_t* addr, int32_t inc) { |
| 29 | return _InterlockedExchangeAdd(reinterpret_cast<long*>(addr), static_cast<long>(inc)); |
| 30 | } |
| 31 | |
| 32 | static inline int32_t sk_atomic_dec(int32_t* addr) { |
| 33 | // InterlockedDecrement returns the new value, we want to return the old. |
| 34 | return _InterlockedDecrement(reinterpret_cast<long*>(addr)) + 1; |
| 35 | } |
| 36 | |
| 37 | static inline void sk_membar_acquire__after_atomic_dec() { } |
| 38 | |
| 39 | static inline int32_t sk_atomic_conditional_inc(int32_t* addr) { |
| 40 | long value = *addr; |
| 41 | while (true) { |
| 42 | if (value == 0) { |
| 43 | return 0; |
| 44 | } |
| 45 | |
| 46 | long before = _InterlockedCompareExchange(reinterpret_cast<long*>(addr), value + 1, value); |
| 47 | |
| 48 | if (before == value) { |
| 49 | return value; |
| 50 | } else { |
| 51 | value = before; |
| 52 | } |
| 53 | } |
| 54 | } |
| 55 | |
| 56 | static inline void sk_membar_acquire__after_atomic_conditional_inc() { } |
| 57 | |
| 58 | #endif |