Ichthyostega
22322dfec4
...no need to keep them in util.hpp, as they are used rather occasionally, while util.hpp is used pervasively.
119 lines
3 KiB
C++
119 lines
3 KiB
C++
/*
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UTIL-QUANT.hpp - helper functions to deal with division and quantisation
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Copyright (C) Lumiera.org
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2011, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef LIB_UTIL_QUANT_H
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#define LIB_UTIL_QUANT_H
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#include <cstdlib>
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namespace util {
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/** helper to treat int or long division uniformly */
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template<typename I>
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struct IDiv
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{
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I quot;
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I rem;
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IDiv (I num, I den)
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: quot(num/den)
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, rem(num - quot*den)
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{ }
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};
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template<>
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struct IDiv<int>
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: div_t
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{
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IDiv<int> (int num, int den)
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: div_t(div (num,den))
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{ }
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};
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template<>
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struct IDiv<long>
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: ldiv_t
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{
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IDiv<long> (long num, long den)
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: ldiv_t(ldiv (num,den))
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{ }
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};
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template<>
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struct IDiv<long long>
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: lldiv_t
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{
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IDiv<long long> (long long num, long long den)
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: lldiv_t(lldiv (num,den))
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{ }
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};
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/** floor function for integer arithmetics.
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* Unlike the built-in integer division, this function
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* always rounds towards the next \em smaller integer,
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* even for negative numbers.
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* @warning floor on doubles performs way better
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* @see UtilFloordiv_test
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*/
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template<typename I>
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inline I
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floordiv (I num, I den)
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{
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if (0 < (num^den))
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return num/den;
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else
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{ // truncate similar to floor()
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IDiv<I> res(num,den);
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return (res.rem)? res.quot-1 // negative results truncated towards next smaller int
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: res.quot; //..unless the division result not truncated at all
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}
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}
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/** scale wrapping operation.
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* Quantises the numerator value into the scale given by the denominator.
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* Unlike the built-in integer division, this function always rounds towards
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* the next \em smaller integer and also relates the remainder (=modulo) to
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* this next lower scale grid point.
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* @return quotient and remainder packed into a struct
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* @see UtilFloorwarp_test
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*/
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template<typename I>
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inline IDiv<I>
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floorwrap (I num, I den)
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{
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IDiv<I> res(num,den);
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if (0 > (num^den) && res.rem)
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{ // negative results
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// wrapped similar to floor()
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--res.quot;
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res.rem = den - (-res.rem);
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}
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return res;
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}
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} // namespace util
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#endif /*UTIL_QUANT_H*/
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