Sprout/sprout/math/float_sig_exp.hpp
2019-01-07 17:47:17 +09:00

61 lines
2.2 KiB
C++

/*=============================================================================
Copyright (c) 2011-2019 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_FLOAT_SIG_EXP_HPP
#define SPROUT_MATH_FLOAT_SIG_EXP_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/isnan.hpp>
#include <sprout/math/ilogb.hpp>
#include <sprout/type_traits/enabler_if.hpp>
#include <sprout/utility/pair/pair.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR sprout::pair<T, int>
float_sig_exp_impl(T x, int exp) {
typedef sprout::pair<T, int> type;
return type(x / sprout::detail::pow_n(T(sprout::numeric_limits<T>::radix), exp), exp);
}
} // namespace detail
//
// float_sig_exp
//
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR sprout::pair<FloatType, int>
float_sig_exp(FloatType x) {
typedef sprout::pair<FloatType, int> type;
return sprout::math::isnan(x) ? type(x, 0)
: x == sprout::numeric_limits<FloatType>::infinity() ? type(sprout::numeric_limits<FloatType>::infinity(), 0)
: x == -sprout::numeric_limits<FloatType>::infinity() ? type(-sprout::numeric_limits<FloatType>::infinity(), 0)
: x == 0 ? type(x, 0)
: sprout::math::detail::float_sig_exp_impl(x, sprout::math::ilogb(x) + 1)
;
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR sprout::pair<double, int>
float_sig_exp(IntType x) {
return sprout::math::float_sig_exp(static_cast<double>(x));
}
} // namespace math
using sprout::math::float_sig_exp;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_FLOAT_SIG_EXP_HPP