| // Copyright 2016 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BASE_BIT_CAST_H_ |
| #define BASE_BIT_CAST_H_ |
| |
| #include "base/compiler_specific.h" |
| |
| #if !HAS_BUILTIN(__builtin_bit_cast) |
| #include <string.h> |
| #include "base/template_util.h" |
| #endif |
| |
| // This is C++20's std::bit_cast<>(). |
| // It morally does what `*reinterpret_cast<Dest*>(&source)` does, but the cast/deref pair |
| // is undefined behavior, while bit_cast<>() isn't. |
| template <class Dest, class Source> |
| #if HAS_BUILTIN(__builtin_bit_cast) |
| constexpr |
| #else |
| inline |
| #endif |
| Dest |
| bit_cast(const Source& source) { |
| #if HAS_BUILTIN(__builtin_bit_cast) |
| // TODO(thakis): Keep only this codepath once nacl is gone or updated. |
| return __builtin_bit_cast(Dest, source); |
| #else |
| static_assert(sizeof(Dest) == sizeof(Source), |
| "bit_cast requires source and destination to be the same size"); |
| static_assert(base::is_trivially_copyable<Dest>::value, |
| "bit_cast requires the destination type to be copyable"); |
| static_assert(base::is_trivially_copyable<Source>::value, |
| "bit_cast requires the source type to be copyable"); |
| |
| Dest dest; |
| memcpy(&dest, &source, sizeof(dest)); |
| return dest; |
| #endif |
| } |
| |
| #endif // BASE_BIT_CAST_H_ |