Root/lib/int_sqrt.c

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

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