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