Factor out bit_cast.

1 files changed, 40 insertions, 0 deletions

diff --git a/src/support/utilities.h b/src/support/utilities.h
new file mode 100644
index 000000000..77263a78e
--- /dev/null
+++ b/src/support/utilities.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2016 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_support_utilities_h
+#define wasm_support_utilities_h
+
+#include <cstring>
+#include <type_traits>
+
+namespace wasm {
+
+// Type punning needs to be done through this function to avoid undefined
+// behavior: unions and reinterpret_cast aren't valid approaches.
+template <class Destination, class Source>
+inline Destination bit_cast(const Source& source) {
+  static_assert(sizeof(Destination) == sizeof(Source),
+                "bit_cast needs to be between types of the same size");
+  static_assert(std::is_pod<Destination>::value, "non-POD bit_cast undefined");
+  static_assert(std::is_pod<Source>::value, "non-POD bit_cast undefined");
+  Destination destination;
+  std::memcpy(&destination, &source, sizeof(destination));
+  return destination;
+}
+
+}  // namespace wasm
+
+#endif   // wasm_support_utilities_h