63e88f80
 Hu Chunming
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// (C) Copyright Christopher Kormanyos 1999 - 2021.
// (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_FREXP_HPP
#define BOOST_MATH_CCMATH_FREXP_HPP
#include <cmath>
#include <limits>
#include <type_traits>
#include <boost/math/ccmath/isinf.hpp>
#include <boost/math/ccmath/isnan.hpp>
#include <boost/math/ccmath/isfinite.hpp>
namespace boost::math::ccmath {
namespace detail
{
template <typename Real>
inline constexpr Real frexp_zero_impl(Real arg, int* exp)
{
*exp = 0;
return arg;
}
template <typename Real>
inline constexpr Real frexp_impl(Real arg, int* exp)
{
const bool negative_arg = (arg < Real(0));
Real f = negative_arg ? -arg : arg;
int e2 = 0;
constexpr Real two_pow_32 = Real(4294967296);
while (f >= two_pow_32)
{
f = f / two_pow_32;
e2 += 32;
}
while(f >= Real(1))
{
f = f / Real(2);
++e2;
}
if(exp != nullptr)
{
*exp = e2;
}
return !negative_arg ? f : -f;
}
} // namespace detail
template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
inline constexpr Real frexp(Real arg, int* exp)
{
if(BOOST_MATH_IS_CONSTANT_EVALUATED(arg))
{
return arg == Real(0) ? detail::frexp_zero_impl(arg, exp) :
arg == Real(-0) ? detail::frexp_zero_impl(arg, exp) :
boost::math::ccmath::isinf(arg) ? detail::frexp_zero_impl(arg, exp) :
boost::math::ccmath::isnan(arg) ? detail::frexp_zero_impl(arg, exp) :
boost::math::ccmath::detail::frexp_impl(arg, exp);
}
else
{
using std::frexp;
return frexp(arg, exp);
}
}
template <typename Z, std::enable_if_t<std::is_integral_v<Z>, bool> = true>
inline constexpr double frexp(Z arg, int* exp)
{
return boost::math::ccmath::frexp(static_cast<double>(arg), exp);
}
inline constexpr float frexpf(float arg, int* exp)
{
return boost::math::ccmath::frexp(arg, exp);
}
#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
inline constexpr long double frexpl(long double arg, int* exp)
{
return boost::math::ccmath::frexp(arg, exp);
}
#endif
}
#endif // BOOST_MATH_CCMATH_FREXP_HPP
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