1/*
2 * Copyright (C) 2019 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef StdLibExtras_h
27#define StdLibExtras_h
28
29#include "BCompiler.h"
30#include <memory>
31#include <type_traits>
32
33namespace bmalloc {
34
35template<typename ToType, typename FromType>
36inline ToType bitwise_cast(FromType from)
37{
38 static_assert(sizeof(FromType) == sizeof(ToType), "bitwise_cast size of FromType and ToType must be equal!");
39#if BCOMPILER_HAS_CLANG_FEATURE(is_trivially_copyable)
40 // Not all recent STL implementations support the std::is_trivially_copyable type trait. Work around this by only checking on toolchains which have the equivalent compiler intrinsic.
41 static_assert(__is_trivially_copyable(ToType), "bitwise_cast of non-trivially-copyable type!");
42 static_assert(__is_trivially_copyable(FromType), "bitwise_cast of non-trivially-copyable type!");
43#endif
44 typename std::remove_const<ToType>::type to { };
45 memcpy(static_cast<void*>(&to), static_cast<void*>(&from), sizeof(to));
46 return to;
47}
48
49} // namespace bmalloc
50
51#endif // StdLibExtras_h
52