Sprout/sprout/math/fdim.hpp
2015-01-10 19:13:57 +09:00

76 lines
2.6 KiB
C++

/*=============================================================================
Copyright (c) 2011-2015 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef SPROUT_MATH_FDIM_HPP
#define SPROUT_MATH_FDIM_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/limits.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/isnan.hpp>
#include <sprout/type_traits/float_promote.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
inline SPROUT_CONSTEXPR float
builtin_fdim(float x, float y) {
return __builtin_fdimf(x, y);
}
inline SPROUT_CONSTEXPR double
builtin_fdim(double x, double y) {
return __builtin_fdim(x, y);
}
inline SPROUT_CONSTEXPR long double
builtin_fdim(long double x, long double y) {
return __builtin_fdiml(x, y);
}
#endif
} // namespace detail
//
// fdim
//
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
fdim(FloatType x, FloatType y) {
return sprout::math::isnan(y) ? y
: sprout::math::isnan(x) ? x
: x == sprout::numeric_limits<FloatType>::infinity() ? sprout::numeric_limits<FloatType>::infinity()
: x == -sprout::numeric_limits<FloatType>::infinity() ? FloatType(0)
: y == sprout::numeric_limits<FloatType>::infinity() ? FloatType(0)
: y == -sprout::numeric_limits<FloatType>::infinity() ? sprout::numeric_limits<FloatType>::infinity()
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
: sprout::math::detail::builtin_fdim(x, y)
#else
: x > y ? x - y : FloatType(0)
#endif
;
}
template<
typename ArithmeticType1,
typename ArithmeticType2,
typename sprout::enabler_if<
std::is_arithmetic<ArithmeticType1>::value && std::is_arithmetic<ArithmeticType2>::value
>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type
fdim(ArithmeticType1 x, ArithmeticType2 y) {
typedef typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type type;
return sprout::math::fdim(static_cast<type>(x), static_cast<type>(y));
}
} // namespace math
using sprout::math::fdim;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_FDIM_HPP