initial commit, 4.5 stable

thirdparty/embree/common/sys/atomic.h

@@ -0,0 +1,59 @@
+// Copyright 2009-2021 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include <atomic>
+#include "intrinsics.h"
+
+namespace embree
+{
+/* compiler memory barriers */
+#if defined(__INTEL_COMPILER)
+//#define __memory_barrier() __memory_barrier()
+#elif defined(__GNUC__) || defined(__clang__)
+#  define __memory_barrier() asm volatile("" ::: "memory")
+#elif  defined(_MSC_VER)
+#  define __memory_barrier() _ReadWriteBarrier()
+#endif
+
+  template <typename T>
+    struct atomic : public std::atomic<T>
+  {
+    atomic () {}
+      
+    atomic (const T& a)
+      : std::atomic<T>(a) {}
+
+    atomic (const atomic<T>& a) {
+      this->store(a.load());
+    }
+
+    atomic& operator=(const atomic<T>& other) {
+      this->store(other.load());
+      return *this;
+    }
+  };
+
+  template<typename T>
+    __forceinline void _atomic_min(std::atomic<T>& aref, const T& bref)
+  {
+    const T b = bref.load();
+    while (true) {
+      T a = aref.load();
+      if (a <= b) break;
+      if (aref.compare_exchange_strong(a,b)) break;
+    }
+  }
+
+  template<typename T>
+    __forceinline void _atomic_max(std::atomic<T>& aref, const T& bref)
+  {
+    const T b = bref.load();
+    while (true) {
+      T a = aref.load();
+      if (a >= b) break;
+      if (aref.compare_exchange_strong(a,b)) break;
+    }
+  }
+}