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https://github.com/bolero-MURAKAMI/Sprout.git
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67 lines
2 KiB
C++
67 lines
2 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2015 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_MATH_SIGNBIT_HPP
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#define SPROUT_MATH_SIGNBIT_HPP
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/math/detail/config.hpp>
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#include <sprout/math/copysign.hpp>
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#include <sprout/type_traits/enabler_if.hpp>
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namespace sprout {
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namespace math {
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namespace detail {
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#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
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template<typename FloatType>
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inline SPROUT_CONSTEXPR bool
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builtin_signbit(FloatType x) {
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return __builtin_signbit(x);
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}
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#endif
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} // namespace detail
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//
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// signbit
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//
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// issue:
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// [ !(SPROUT_USE_BUILTIN_CMATH_FUNCTION || SPROUT_USE_BUILTIN_COPYSIGN_FUNCTION) ]
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// signbit(-0) returns false .
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// # returns true . ( same as signbit(+0) )
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// signbit(-NaN) returns false .
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// # returns true . ( same as signbit(+NaN) )
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//
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template<
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typename FloatType,
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typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
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>
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inline SPROUT_CONSTEXPR bool
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signbit(FloatType x) {
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return
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#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
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sprout::math::detail::builtin_signbit(x)
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#elif SPROUT_USE_BUILTIN_COPYSIGN_FUNCTION
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sprout::math::copysign(FloatType(1), x) < FloatType(0)
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#else
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sprout::math::detail::broken_signbit(x)
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#endif
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;
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}
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template<
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typename IntType,
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typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
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>
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inline SPROUT_CONSTEXPR bool
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signbit(IntType x) {
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return x < 0;
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}
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} // namespace math
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using sprout::math::signbit;
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} // namespace sprout
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#endif // #ifndef SPROUT_MATH_SIGNBIT_HPP
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