acrn-kernel/lib/int_sqrt.c

33 lines
514 B
C

#include <linux/kernel.h>
#include <linux/module.h>
/**
* int_sqrt - rough approximation to sqrt
* @x: integer of which to calculate the sqrt
*
* A very rough approximation to the sqrt() function.
*/
unsigned long int_sqrt(unsigned long x)
{
unsigned long op, res, one;
op = x;
res = 0;
one = 1 << 30;
while (one > op)
one >>= 2;
while (one != 0) {
if (op >= res + one) {
op = op - (res + one);
res = res + 2 * one;
}
res /= 2;
one /= 4;
}
return res;
}
EXPORT_SYMBOL(int_sqrt);