Split atomic and mutex implementations and make inlinable.

src/ports/SkAtomics_win.h

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