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// (C) Copyright Matt Borland 2021.
// Use, modification and distribution are subject to 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 BOOST_MATH_CCMATH_FLOOR_HPP
#define BOOST_MATH_CCMATH_FLOOR_HPP
#include <boost/math/ccmath/detail/config.hpp>
#ifdef BOOST_MATH_NO_CCMATH
#error "The header <boost/math/floor.hpp> can only be used in C++17 and later."
#endif
#include <boost/math/ccmath/abs.hpp>
#include <boost/math/ccmath/isinf.hpp>
#include <boost/math/ccmath/isnan.hpp>
#include <limits>
namespace boost::math::ccmath {
namespace detail {
template <typename T>
inline constexpr T floor_pos_impl(T arg) noexcept
{
constexpr auto max_comp_val = T(1) / std::numeric_limits<T>::epsilon();
if (arg >= max_comp_val)
{
return arg;
}
T result = 1;
if(result <= arg)
{
while(result < arg)
{
result *= 2;
}
while(result > arg)
{
--result;
}
return result;
}
else
{
return T(0);
}
}
template <typename T>
inline constexpr T floor_neg_impl(T arg) noexcept
{
T result = -1;
if(result > arg)
{
while(result > arg)
{
result *= 2;
}
while(result < arg)
{
++result;
}
if(result != arg)
{
--result;
}
}
return result;
}
template <typename T>
inline constexpr T floor_impl(T arg) noexcept
{
if(arg > 0)
{
return floor_pos_impl(arg);
}
else
{
return floor_neg_impl(arg);
}
}
} // Namespace detail
template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
inline constexpr Real floor(Real arg) noexcept
{
if(BOOST_MATH_IS_CONSTANT_EVALUATED(arg))
{
return boost::math::ccmath::abs(arg) == Real(0) ? arg :
boost::math::ccmath::isinf(arg) ? arg :
boost::math::ccmath::isnan(arg) ? arg :
boost::math::ccmath::detail::floor_impl(arg);
}
else
{
using std::floor;
return floor(arg);
}
}
template <typename Z, std::enable_if_t<std::is_integral_v<Z>, bool> = true>
inline constexpr double floor(Z arg) noexcept
{
return boost::math::ccmath::floor(static_cast<double>(arg));
}
inline constexpr float floorf(float arg) noexcept
{
return boost::math::ccmath::floor(arg);
}
#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
inline constexpr long double floorl(long double arg) noexcept
{
return boost::math::ccmath::floor(arg);
}
#endif
} // Namespaces
#endif // BOOST_MATH_CCMATH_FLOOR_HPP
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