mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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105 lines
3 KiB
C++
105 lines
3 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2014 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef SPROUT_BIT_PARITY_HPP
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#define SPROUT_BIT_PARITY_HPP
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#include <cstddef>
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#include <climits>
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#include <type_traits>
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#include <sprout/config.hpp>
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//#include <sprout/bit/popcount.hpp>
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#include <sprout/bit/shlr.hpp>
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namespace sprout {
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namespace detail {
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# if SPROUT_USE_BUILTIN_BIT_OPERATION
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inline SPROUT_CONSTEXPR int
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parity(unsigned x) {
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return __builtin_parity(x);
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}
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inline SPROUT_CONSTEXPR int
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parity(unsigned long x) {
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return __builtin_parityl(x);
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}
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inline SPROUT_CONSTEXPR int
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parity(unsigned long long x) {
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return __builtin_parityll(x);
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}
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# endif
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// template<typename Integral>
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// inline SPROUT_CONSTEXPR int
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// parity(Integral x) {
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// return sprout::popcount(x) & 1;
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// }
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template<std::size_t N, typename Integral>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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(N == 1),
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Integral
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>::type
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parity_bytes(Integral x) SPROUT_NOEXCEPT {
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return x;
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}
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template<std::size_t N, typename Integral>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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(N > 1),
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Integral
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>::type
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parity_bytes(Integral x) SPROUT_NOEXCEPT {
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return sprout::detail::parity_bytes<N / 2>(
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x ^ sprout::shlr(x, N / 2 * CHAR_BIT)
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);
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}
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template<typename Integral>
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inline SPROUT_CONSTEXPR Integral
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parity_bytes(Integral x) SPROUT_NOEXCEPT {
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return sprout::detail::parity_bytes<sizeof(Integral)>(x);
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}
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template<typename Integral>
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inline SPROUT_CONSTEXPR Integral
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parity_bits4(Integral x) SPROUT_NOEXCEPT {
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return x ^ sprout::shlr(x, 4);
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}
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template<typename Integral>
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inline SPROUT_CONSTEXPR Integral
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parity_bits2(Integral x) SPROUT_NOEXCEPT {
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return sprout::detail::parity_bits4(
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x ^ sprout::shlr(x, 2)
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);
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}
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template<typename Integral>
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inline SPROUT_CONSTEXPR Integral
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parity_bits1(Integral x) SPROUT_NOEXCEPT {
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return sprout::detail::parity_bits2(
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x ^ sprout::shlr(x, 1)
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);
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}
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template<typename Integral>
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inline SPROUT_CONSTEXPR Integral
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parity_bits(Integral x) SPROUT_NOEXCEPT {
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return sprout::detail::parity_bits1(x);
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}
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template<typename Integral>
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inline SPROUT_CONSTEXPR int
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parity(Integral x) {
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return static_cast<int>(sprout::detail::parity_bytes(sprout::detail::parity_bits(x))) & 1;
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}
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} // namespace detail
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//
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// parity
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//
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template<typename Integral>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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std::is_integral<Integral>::value,
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int
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>::type
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parity(Integral x) {
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return sprout::detail::parity(x);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_BIT_PARITY_HPP
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