libcruft-util/maths.ipp
2015-11-13 17:25:21 +11:00

65 lines
1.6 KiB
C++

/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* 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>
constexpr T
util::pow (T x, unsigned y)
{
if (y == 0)
return T(1);
return x * util::pow (x, y - 1);
}
///////////////////////////////////////////////////////////////////////////////
/// Return a unit type with a sign that matches the provided value
///
/// We were using __builtin_signbit for the potential speedboost, but it causes
/// problems with constexpr under clang. If you need speed then you'll probably
/// have to handcode something.
constexpr int
sign (int v)
{
return std::signbit (v) ? -1 : 1;
}
//-----------------------------------------------------------------------------
constexpr float
sign (float v)
{
return std::signbit (v) ? -1.f : 1.f;
}
//-----------------------------------------------------------------------------
constexpr double
sign (double v)
{
return std::signbit (v) ? -1. : 1.f;
}