Sprout/sprout/math/floor.hpp
2013-08-07 00:15:09 +09:00

68 lines
2.2 KiB
C++

#ifndef SPROUT_MATH_FLOOR_HPP
#define SPROUT_MATH_FLOOR_HPP
#include <cstdint>
#include <type_traits>
#include <stdexcept>
#include <sprout/config.hpp>
#include <sprout/limits.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/detail/float_compute.hpp>
#include <sprout/math/isnan.hpp>
#include <sprout/math/equal_to.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
floor_impl_1(T x, T x0) {
return sprout::math::equal_to(x, x0) ? x0
: x0 - T(1)
;
}
template<typename T>
inline SPROUT_CONSTEXPR T
floor_impl(T x) {
return x < 0 ? sprout::math::detail::floor_impl_1(x, -static_cast<T>(static_cast<std::uintmax_t>(-x)))
: static_cast<T>(static_cast<std::uintmax_t>(x))
;
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
floor(FloatType x) {
return 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()
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
: std::floor(x)
#else
: x == 0 ? x
: sprout::numeric_limits<std::uintmax_t>::max() < x || sprout::numeric_limits<std::uintmax_t>::max() < -x
? SPROUT_MATH_THROW_LARGE_FLOAT_ROUNDING(std::runtime_error("floor: large float rounding."), x)
: static_cast<FloatType>(sprout::math::detail::floor_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
floor(IntType x) {
return sprout::math::detail::floor(static_cast<double>(x));
}
} // namespace detail
using sprout::math::detail::floor;
} // namespace math
using sprout::math::floor;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_FLOOR_HPP