const.h

/*  This file is part of the Vc library. {{{
Copyright © 2013-2015 Matthias Kretz <kretz@kde.org>
 
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      derived from this software without specific prior written permission.
 
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}}}*/
 
#ifndef VC_COMMON_CONST_H_
#define VC_COMMON_CONST_H_
 
#include <type_traits>
#include "../global.h"
 
namespace Vc_VERSIONED_NAMESPACE
{
namespace Detail
{
 
template <int exponent> constexpr double exponentToFloat(std::integral_constant<bool, true>);
template <int exponent> constexpr double exponentToFloat(std::integral_constant<bool, false>);
template <> constexpr double exponentToFloat<0>(std::integral_constant<bool, true>)
{
    return 1.;
}
template <> constexpr double exponentToFloat<0>(std::integral_constant<bool, false>)
{
    return 1.;
}
template <> constexpr double exponentToFloat<-32>(std::integral_constant<bool, true>)
{
    return 1. / (65536. * 65536.);
}
template <> constexpr double exponentToFloat<32>(std::integral_constant<bool, false>)
{
    return 65536. * 65536.;
}
template <> constexpr double exponentToFloat<-64>(std::integral_constant<bool, true>)
{
    return 1. / (65536. * 65536. * 65536. * 65536.);
}
template <> constexpr double exponentToFloat<64>(std::integral_constant<bool, false>)
{
    return 65536. * 65536. * 65536. * 65536.;
}
template <int exponent>
constexpr double exponentToFloat(std::integral_constant<bool, false> negative)
{
    return exponentToFloat<exponent - 1>(negative) * 2.0;
}
template <int exponent>
constexpr double exponentToFloat(std::integral_constant<bool, true> negative)
{
    return exponentToFloat<exponent + 1>(negative) * 0.5;
}
template <int sign, unsigned long long mantissa, int exponent> constexpr double doubleConstant()
{
    return (static_cast<double>((mantissa & 0x000fffffffffffffull) | 0x0010000000000000ull) /
            0x0010000000000000ull) *
           exponentToFloat<exponent>(std::integral_constant<bool, (exponent < 0)>()) * sign;
}
template <int sign, unsigned int mantissa, int exponent> constexpr float floatConstant()
{
    return (static_cast<float>((mantissa & 0x007fffffu) | 0x00800000u) / 0x00800000u) *
           static_cast<float>(
               exponentToFloat<exponent>(std::integral_constant<bool, (exponent < 0)>())) *
           sign;
}
 
}  // namespace Detail
}  // namespace Vc
 
#endif // VC_COMMON_CONST_H_