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

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2.5 KiB
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/*=============================================================================
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_LDEXP_HPP
#define SPROUT_MATH_LDEXP_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_ldexp(float x, int exp) {
return __builtin_ldexpf(x, exp);
}
inline SPROUT_CONSTEXPR double
builtin_ldexp(double x, int exp) {
return __builtin_ldexp(x, exp);
}
inline SPROUT_CONSTEXPR long double
builtin_ldexp(long double x, int exp) {
return __builtin_ldexpl(x, exp);
}
#endif
template<typename T>
inline SPROUT_CONSTEXPR T
ldexp_impl(T x, int exp) {
return x * sprout::detail::pow_n(T(2), exp);
}
} // namespace detail
//
// ldexp
//
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
ldexp(FloatType x, int exp) {
return
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
sprout::math::detail::builtin_ldexp(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::ldexp_impl(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
ldexp(IntType x, int exp) {
return sprout::math::ldexp(static_cast<double>(x), exp);
}
} // namespace math
using sprout::math::ldexp;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_LDEXP_HPP