47 lines
1.0 KiB
C
47 lines
1.0 KiB
C
|
/*
|
||
|
* See file CREDITS for list of people who contributed to this
|
||
|
* project.
|
||
|
*
|
||
|
* This program is free software; you can redistribute it and/or
|
||
|
* modify it under the terms of the GNU General Public License as
|
||
|
* published by the Free Software Foundation; either version 2 of
|
||
|
* the License, or (at your option) any later version.
|
||
|
*
|
||
|
* This program is distributed in the hope that it will be useful,
|
||
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
* GNU General Public License for more details.
|
||
|
*
|
||
|
*/
|
||
|
|
||
|
#include <common.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 << (BITS_PER_LONG - 2);
|
||
|
while (m != 0) {
|
||
|
b = y + m;
|
||
|
y >>= 1;
|
||
|
|
||
|
if (x >= b) {
|
||
|
x -= b;
|
||
|
y += m;
|
||
|
}
|
||
|
m >>= 2;
|
||
|
}
|
||
|
|
||
|
return y;
|
||
|
}
|
||
|
EXPORT_SYMBOL(int_sqrt);
|