47 lines
1.6 KiB
C++
47 lines
1.6 KiB
C++
// The MIT License (MIT)
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//
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// Copyright (c) 2018 Mateusz Pusz
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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#pragma once
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#include <cassert>
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#include <cstdint>
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namespace units::detail {
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template<std::intmax_t N, typename T>
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constexpr T pow_impl(const T& v) noexcept
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{
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if constexpr (N == 0) {
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return T(1);
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} else if constexpr (N == 1) {
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return v;
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} else if constexpr (N < 0) {
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return 1 / pow_impl<-N>(v);
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} else if constexpr (N % 2 == 0) { // even
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return pow_impl<N / 2>(v * v);
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} else { // odd
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return v * pow_impl<(N - 1) / 2>(v * v);
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}
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}
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} // namespace units::detail
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