libcruft-util/maths.ipp

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/*
* This file is part of libgim.
*
* libgim is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* libgim is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2014 Danny Robson <danny@nerdcruft.net>
*/
#ifndef __UTIL_MATHS_IPP
#define __UTIL_MATHS_IPP
#else
#error "Include only once"
#endif
#include <type_traits>
//-----------------------------------------------------------------------------
template <typename T, typename U>
typename std::common_type<T,U>::type
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align (T value, U size) {
static_assert (std::is_integral<T>::value, "align requires integral types");
static_assert (std::is_integral<U>::value, "align requires integral types");
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return divup (value, size) * size;
}
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//-----------------------------------------------------------------------------
template <typename T>
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constexpr T
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pow (T x, unsigned y)
{
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return y == 0 ? 1 : x * pow (x, y - 1);
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}
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///----------------------------------------------------------------------------
/// Return a unit type with a sign that matches the provided value
///
/// This really needs to be inline for performance as it's used in a few inner
/// loops where the possibility of a function call is a deal breaker.
constexpr int
sign (int v)
{
return __builtin_signbitl (v) ? -1 : 1;
}
constexpr float
sign (float v)
{
return __builtin_signbitf (v) ? -1.f : 1.f;
}
constexpr double
sign (double v)
{
return __builtin_signbit (v) ? -1. : 1.f;
}
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//-----------------------------------------------------------------------------
template <>
struct constants<float>
{
static constexpr float PI = PI_f;
static constexpr float E = E_f;
};
template <>
struct constants<double>
{
static constexpr double PI = PI_d;
static constexpr double E = E_d;
};