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42 lines
988 B
42 lines
988 B
2 years ago
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#pragma once
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#ifdef __cpp_lib_bit_cast
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#include <bit>
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namespace drake {
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namespace internal {
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using std::bit_cast;
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} // namespace internal
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} // namespace drake
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#else // __cpp_lib_bit_cast
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#include <cstring>
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#include <type_traits>
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namespace drake {
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namespace internal {
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/* Implements C++20 https://en.cppreference.com/w/cpp/numeric/bit_cast (but
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without the overload resolution guards, which are not necessary in our case.)
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(Once all of Drake's supported platforms offer std::bit_cast, we can remove
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this function in lieu of the std one.) */
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template <class To, class From>
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To bit_cast(const From& from) noexcept {
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static_assert(std::is_trivially_constructible_v<To>);
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To result;
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static_assert(sizeof(To) == sizeof(From));
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static_assert(std::is_trivially_copyable_v<To>);
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static_assert(std::is_trivially_copyable_v<From>);
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std::memcpy(&result, &from, sizeof(result));
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return result;
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}
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} // namespace internal
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} // namespace drake
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#endif // __cpp_lib_bit_cast
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