Sprout/sprout/math/scalbln.hpp
2016-02-25 18:48:28 +09:00

79 lines
2.6 KiB
C++

/*=============================================================================
Copyright (c) 2011-2016 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_SCALBLN_HPP
#define SPROUT_MATH_SCALBLN_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/limits.hpp>
#include <sprout/detail/pow.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/detail/float_compute.hpp>
#include <sprout/math/isnan.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_scalbln(float x, long exp) {
return __builtin_scalblnf(x, exp);
}
inline SPROUT_CONSTEXPR double
builtin_scalbln(double x, long exp) {
return __builtin_scalbln(x, exp);
}
inline SPROUT_CONSTEXPR long double
builtin_scalbln(long double x, long exp) {
return __builtin_scalblnl(x, exp);
}
#endif
template<typename FloatType, typename T>
inline SPROUT_CONSTEXPR T
scalbln_impl(T x, long exp) {
return x * sprout::detail::pow_n(T(sprout::numeric_limits<FloatType>::radix), exp);
}
} // namespace detail
//
// scalbln
//
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
scalbln(FloatType x, long exp) {
return
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
sprout::math::detail::builtin_scalbln(x, exp)
#else
sprout::math::isnan(x) ? x
: x == sprout::numeric_limits<FloatType>::infinity() ? sprout::numeric_limits<FloatType>::infinity()
: x == -sprout::numeric_limits<FloatType>::infinity() ? -sprout::numeric_limits<FloatType>::infinity()
: exp == 0 ? x
: x == 0 ? x
: static_cast<FloatType>(sprout::math::detail::scalbln_impl<FloatType>(static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(x), exp))
#endif
;
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
scalbln(IntType x, long exp) {
return sprout::math::scalbln(static_cast<double>(x), exp);
}
} // namespace math
using sprout::math::scalbln;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_SCALBLN_HPP