libcruft-util/maths.cpp

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/*
* This file is part of libgim.
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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.
*
* 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.
*
* 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 Danny Robson <danny@nerdcruft.net>
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*/
#include "maths.hpp"
#include "float.hpp"
#include <cmath>
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#include <type_traits>
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//-----------------------------------------------------------------------------
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template <typename T>
bool
is_pow2 (T value) {
typedef typename std::enable_if<std::is_integral<T>::value, bool>::type return_type;
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return (return_type)(value && !(value & (value - 1)));
}
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template bool is_pow2 (uint8_t);
template bool is_pow2 (uint16_t);
template bool is_pow2 (uint32_t);
template bool is_pow2 (uint64_t);
//-----------------------------------------------------------------------------
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template <typename T>
double
rootsquare (T a, T b)
{ return sqrt (pow2 (a) + pow2 (b)); }
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template double rootsquare (double, double);
template double rootsquare ( int, int);
//-----------------------------------------------------------------------------
template <typename T>
bool
is_integer (const T &value) {
T integer;
return exactly_equal (std::modf (value, &integer),
static_cast<T> (0.0));
}
template bool is_integer (const double&);
template bool is_integer (const float&);
//-----------------------------------------------------------------------------
template <>
unsigned
digits (const uint32_t &v) {
return (v >= 1000000000) ? 10 :
(v >= 100000000) ? 9 :
(v >= 10000000) ? 8 :
(v >= 1000000) ? 7 :
(v >= 100000) ? 6 :
(v >= 10000) ? 5 :
(v >= 1000) ? 4 :
(v >= 100) ? 3 :
(v >= 10) ? 2 :
1;
}
//-----------------------------------------------------------------------------
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template <>
bool
almost_equal (const float &a, const float &b)
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{ return ieee_single::almost_equal (a, b); }
template <>
bool
almost_equal (const double &a, const double &b)
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{ return ieee_double::almost_equal (a, b); }
//-----------------------------------------------------------------------------
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template <typename T>
typename std::enable_if<std::is_integral<T>::value, T>::type
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round_up (T value, T align) {
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CHECK_HARD (align > 1);
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return (value + align - 1) / align;
}
//-----------------------------------------------------------------------------
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template <typename T>
T
round_pow2 (T value) {
typedef typename std::enable_if<std::is_integral<T>::value, T>::type return_type;
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--value;
for (unsigned i = 1; i < sizeof (T) * 8; i <<= 1) {
value |= value >> i;
}
++value;
return (return_type)value;
}
template uint8_t round_pow2 (uint8_t);
template uint16_t round_pow2 (uint16_t);
template uint32_t round_pow2 (uint32_t);
template uint64_t round_pow2 (uint64_t);
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//-----------------------------------------------------------------------------
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template <typename T>
int
sign (T val) {
return val >= 0 ? 1 : -1;
}
template <>
int
sign (float val) {
return static_cast<int> (copysign (1.0f, val));
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}
template <>
int
sign (double val) {
return static_cast<int> (copysign (1.0, val));
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}
template int sign (int);