Geografic-Information-System/lib/gmath/max_pow2.c

#include <grass/gis.h>
#include <grass/gmath.h>


/*!
 * \fn long G_math_max_pow2 (const long n)
 *
 * \brief Finds least power of 2 >= <b>n</b>
 *
 * Finds least power of 2 >= <b>n</b>.
 *
 * \param[in] n
 * \return long
 */

long G_math_max_pow2 (const long n)
{
        long p2, n1;

        n1 = n >> 1;
        p2 = 1;
        while (n1 > 0)
        {
                n1 >>= 1;
                p2 <<= 1;
        }
        if (p2 < n) p2 <<=1;

        return(p2);
}


/*!
 * \fn long G_math_min_pow2 (const long n)
 *
 * \brief Finds largest power of 2 <= <b>n</b>
 *
 * Finds largest power of 2 <= <b>n</b>.
 *
 * \param[in] n
 * \return long
 */

long G_math_min_pow2 (const long n)
{
        long p2, n1;

        n1 = n >> 1;
        p2 = 1;
        while (n1 > 0)
        {
                n1 >>= 1;
                p2 <<= 1;
        }

        return(p2);
}