ia64/linux-2.6.18-xen.hg

view lib/int_sqrt.c @ 912:dd42cdb0ab89

[IA64] Build blktap2 driver by default in x86 builds.

add CONFIG_XEN_BLKDEV_TAP2=y to buildconfigs/linux-defconfig_xen_ia64.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
author Isaku Yamahata <yamahata@valinux.co.jp>
date Mon Jun 29 12:09:16 2009 +0900 (2009-06-29)
parents 831230e53067
children
line source
2 #include <linux/kernel.h>
3 #include <linux/module.h>
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 */
11 unsigned long int_sqrt(unsigned long x)
12 {
13 unsigned long op, res, one;
15 op = x;
16 res = 0;
18 one = 1UL << (BITS_PER_LONG - 2);
19 while (one > op)
20 one >>= 2;
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 }
32 EXPORT_SYMBOL(int_sqrt);