powersOfTwo.h

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/*
 *  Copyright (C) 2012 Josh Bialkowski (jbialk@mit.edu)
 *
 *  This file is part of mpblocks.
 *
 *  mpblocks 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.
 *
 *  mpblocks 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 mpblocks.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef MPBLOCKS_CUDA_POWERS_OF_TWO_H
#define MPBLOCKS_CUDA_POWERS_OF_TWO_H


#include <climits>


namespace mpblocks {
namespace     cuda {





template <typename T>
inline bool isPow2(T x)
{
    return ((x&(x-1))==0);
}





template <typename T>
inline T nextPow2( T x )
{
    if (x == 0)
        return 0;
    --x;
    for(unsigned int i=1; i <= sizeof(T)*CHAR_BIT; i++)
        x |= x >> i;
    return ++x;
}





template <typename T>
inline T prevPow2( T x )
{
    if(x == 0)
        return 0;

    unsigned int i=0;
    for(;x > 0; x >>= 1)
        i++;
    return 1 << (i-1);
}





template <typename T>
inline T intPow( T x, T p)
{
    if (p == 0) return 1;
    if (p == 1) return x;
    return x * intPow<T>(x, p-1);
}





template <typename T>
inline T twoPow( T x )
{
    return 0x01 << x;
}





template <typename T>
inline T log2( T x )
{
    if(!x)
    {
        return 0;
    }

    else
    {
        T log2x = 0;
        while(  (x & 1) == 0 )
        {
            x >>= 1;
            log2x++;
        }
        return log2x;
    }
}





template <typename T>
inline T times2( const T& x )
{
    return x << 1;
}





template <typename T>
inline T divideBy2( const T& x )
{
    return x >> 1;
}





template <typename T>
inline T intDivideRoundUp(T x, T y)
{
    return (x+y-1)/y;
}





template <typename T>
inline T isOdd(T x)
{
    return ((x & 0x01) == 0x01);
}




template <typename T>
inline T isEven(T x)
{
    return ((x & 0x01) == 0x00);
}





template <unsigned int I, typename T>
inline T getBit(T x)
{
    return x & (0x01 << I);
}




template <typename T>
inline T dividePow2(T x, T y)
{
    return twoPow(log2(x) - log2(y));
}


} // namespace cuda
} // namespace mpblocks


#endif //#ifndef POWERS_OF_TWO_H