/*
|
* Copyright (C) 2013 Davidlohr Bueso <davidlohr.bueso@hp.com>
|
*
|
* Based on the shift-and-subtract algorithm for computing integer
|
* square root from Guy L. Steele.
|
*/
|
|
#include <linux/kernel.h>
|
#include <linux/export.h>
|
#include <linux/bitops.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 b, m, y = 0;
|
|
if (x <= 1)
|
return x;
|
|
m = 1UL << (__fls(x) & ~1UL);
|
while (m != 0) {
|
b = y + m;
|
y >>= 1;
|
|
if (x >= b) {
|
x -= b;
|
y += m;
|
}
|
m >>= 2;
|
}
|
|
return y;
|
}
|
EXPORT_SYMBOL(int_sqrt);
|
