1
2#include <linux/kernel.h>
3#include <linux/module.h>
4
5/**
6 * int_sqrt - rough approximation to sqrt
7 * @x: integer of which to calculate the sqrt
8 *
9 * A very rough approximation to the sqrt() function.
10 */
11unsigned long int_sqrt(unsigned long x)
12{
13	unsigned long op, res, one;
14
15	op = x;
16	res = 0;
17
18	one = 1UL << (BITS_PER_LONG - 2);
19	while (one > op)
20		one >>= 2;
21
22	while (one != 0) {
23		if (op >= res + one) {
24			op = op - (res + one);
25			res = res +  2 * one;
26		}
27		res /= 2;
28		one /= 4;
29	}
30	return res;
31}
32EXPORT_SYMBOL(int_sqrt);
33