libcruft-util/maths.hpp

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/*
* This file is part of libgim.
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*
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* libgim is free software: you can redistribute it and/or modify it under the
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* 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.
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*
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* libgim is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
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*
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* You should have received a copy of the GNU General Public License
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
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*
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* Copyright 2010-2014 Danny Robson <danny@nerdcruft.net>
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*/
#ifndef __MATHS_HPP
#define __MATHS_HPP
#include <type_traits>
#include <utility>
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template <typename T>
T
abs (T value)
{ return value > 0 ? value : -value; }
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//-----------------------------------------------------------------------------
// Exponentials
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template <typename T>
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constexpr T
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pow2 [[gnu::pure]] (T value)
{ return value * value; }
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template <typename T>
bool
is_pow2 [[gnu::pure]] (T value);
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//-----------------------------------------------------------------------------
// Logarithms
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template <typename T>
T
log2 [[gnu::pure]] (T val);
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template <typename T>
T
log2up [[gnu::pure]] (T val);
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//-----------------------------------------------------------------------------
// Roots
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template <typename T>
double
rootsquare [[gnu::pure]] (T a, T b);
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//-----------------------------------------------------------------------------
// Rounding
template <typename T, typename U>
typename std::common_type<T, U>::type
align [[gnu::pure]] (T value, U size);
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template <typename T>
T
round_pow2 [[gnu::pure]] (T value);
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template <typename T, typename U>
T
divup (const T a, const U b)
{ return (a + b - 1) / b; }
//-----------------------------------------------------------------------------
// Classification
template <typename T>
bool
is_integer [[gnu::pure]] (const T& value);
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//-----------------------------------------------------------------------------
// Properties
template <typename T>
unsigned
digits [[gnu::pure]] (const T& value);
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//-----------------------------------------------------------------------------
template <typename T>
int sign (T val);
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//-----------------------------------------------------------------------------
// Comparisons
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template <typename T>
bool
almost_equal (const T &a, const T &b)
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{ return a == b; }
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template <>
bool
almost_equal (const float &a, const float &b);
template <>
bool
almost_equal (const double &a, const double &b);
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template <typename Ta, typename Tb>
typename std::enable_if<
std::is_arithmetic<Ta>::value && std::is_arithmetic<Tb>::value,
bool
>::type
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almost_equal (Ta a, Tb b) {
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return almost_equal <decltype(a + b)> (static_cast<decltype(a + b)>(a),
static_cast<decltype(a + b)>(b));
}
template <typename Ta, typename Tb>
typename std::enable_if<
!std::is_arithmetic<Ta>::value || !std::is_arithmetic<Tb>::value,
bool
>::type
almost_equal (const Ta &a, const Tb &b)
{ return a == b; }
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// Useful for explictly ignore equality warnings
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wfloat-equal"
template <typename T, typename U>
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bool
exactly_equal (const T &a, const U &b)
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{ return a == b; }
#pragma GCC diagnostic pop
template <typename T>
bool
almost_zero (T a)
{ return almost_equal (a, 0); }
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template <typename T>
bool
exactly_zero (T a)
{ return exactly_equal (a, static_cast<T> (0)); }
//-----------------------------------------------------------------------------
constexpr double PI = 3.141592653589793238462643;
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//-----------------------------------------------------------------------------
constexpr double
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to_degrees (double radians) {
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return radians * 180 / PI;
}
//-----------------------------------------------------------------------------
constexpr float
to_radians (float degrees) {
return degrees / 180 * static_cast<float> (PI);
}
constexpr double
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to_radians (double degrees) {
return degrees / 180 * PI;
}
//-----------------------------------------------------------------------------
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/// Variadic minimum
template <typename T>
constexpr T
min (const T a)
{ return a; }
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template <typename T, typename U, typename ...Args>
constexpr typename std::enable_if<
std::is_unsigned<typename std::decay<T>::type>::value == std::is_unsigned<typename std::decay<U>::type>::value &&
std::is_integral<typename std::decay<T>::type>::value == std::is_integral<typename std::decay<U>::type>::value,
typename std::common_type<T,U>::type
>::type
min (const T a, const U b, Args ...args)
{
return min (a < b ? a : b, std::forward<Args> (args)...);
}
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//-----------------------------------------------------------------------------
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/// Variadic maximum
template <typename T>
constexpr T
max (const T a)
{ return a; }
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template <typename T, typename U, typename ...Args>
constexpr typename std::enable_if<
std::is_unsigned<typename std::decay<T>::type>::value == std::is_unsigned<typename std::decay<U>::type>::value &&
std::is_integral<typename std::decay<T>::type>::value == std::is_integral<typename std::decay<U>::type>::value,
typename std::common_type<T,U>::type
>::type
max (const T a, const U b, Args ...args)
{
return max (a > b ? a : b, std::forward<Args> (args)...);
}
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//-----------------------------------------------------------------------------
template <typename T, typename U, typename V>
T
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limit (const T &&val, const U &&hi, const V &&lo)
{
return val > hi ? hi:
val < lo ? lo:
std::move (val);
}
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#include "maths.ipp"
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#endif // __MATHS_HPP