sqrt.cpp

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/*
 * Copyright (C) 2015 Niek Linnenbank
 *
 * This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "math.h"
 
u32 sqrt(u32 number)
{
    u32 op  = number;
    u32 res = 0;
    u32 one = 1uL << 30; // The second-to-top bit is set: use 1u << 14 for uint16_t type; use 1uL<<30 for u32 type
 
    if (number == 0)
        return 0;
 
    // "one" starts at the highest power of four <= than the argument.
    while (one > op)
    {
        one >>= 2;
    }
 
    while (one != 0)
    {
        if (op >= res + one)
        {
            op = op - (res + one);
            res = res +  2 * one;
        }
        res >>= 1;
        one >>= 2;
    }
    return res;
}