mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
synced 2024-11-14 10:39:05 +00:00
79 lines
2.5 KiB
C++
79 lines
2.5 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_LOG2_HPP
|
|
#define SPROUT_MATH_LOG2_HPP
|
|
|
|
#include <type_traits>
|
|
#include <sprout/config.hpp>
|
|
#include <sprout/limits.hpp>
|
|
#include <sprout/math/detail/config.hpp>
|
|
#include <sprout/math/detail/float_compute.hpp>
|
|
#include <sprout/math/constants.hpp>
|
|
#include <sprout/math/isnan.hpp>
|
|
#include <sprout/math/log.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_log2(float x) {
|
|
return __builtin_log2f(x);
|
|
}
|
|
inline SPROUT_CONSTEXPR double
|
|
builtin_log2(double x) {
|
|
return __builtin_log2(x);
|
|
}
|
|
inline SPROUT_CONSTEXPR long double
|
|
builtin_log2(long double x) {
|
|
return __builtin_log2l(x);
|
|
}
|
|
#endif
|
|
|
|
template<typename T>
|
|
inline SPROUT_CONSTEXPR T
|
|
log2_impl(T x) {
|
|
return sprout::math::log(x) / sprout::math::ln_two<T>();
|
|
}
|
|
} // namespace detail
|
|
//
|
|
// log2
|
|
//
|
|
template<
|
|
typename FloatType,
|
|
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
|
|
>
|
|
inline SPROUT_CONSTEXPR FloatType
|
|
log2(FloatType x) {
|
|
return sprout::math::isnan(x) ? x
|
|
: x == 0 ? -sprout::numeric_limits<FloatType>::infinity()
|
|
: x == sprout::numeric_limits<FloatType>::infinity() ? sprout::numeric_limits<FloatType>::infinity()
|
|
: x < 0 ? sprout::numeric_limits<FloatType>::quiet_NaN()
|
|
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
|
|
: sprout::math::detail::builtin_log2(x)
|
|
#else
|
|
: x == 1 ? FloatType(0)
|
|
: static_cast<FloatType>(sprout::math::detail::log2_impl(static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(x)))
|
|
#endif
|
|
;
|
|
}
|
|
template<
|
|
typename IntType,
|
|
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
|
|
>
|
|
inline SPROUT_CONSTEXPR double
|
|
log2(IntType x) {
|
|
return sprout::math::log2(static_cast<double>(x));
|
|
}
|
|
} // namespace math
|
|
|
|
using sprout::math::log2;
|
|
} // namespace sprout
|
|
|
|
#endif // #ifndef SPROUT_MATH_LOG2_HPP
|