[process] Include process name in debug messages
[ipxe.git] / src / core / isqrt.c
1 /*
2 * Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 * 02110-1301, USA.
18 *
19 * You can also choose to distribute this program under the terms of
20 * the Unmodified Binary Distribution Licence (as given in the file
21 * COPYING.UBDL), provided that you have satisfied its requirements.
22 */
23
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25
26 /** @file
27 *
28 * Integer square root
29 *
30 */
31
32 #include <ipxe/isqrt.h>
33
34 /**
35 * Find integer square root
36 *
37 * @v value Value
38 * @v isqrt Integer square root of value
39 */
40 unsigned long isqrt ( unsigned long value ) {
41 unsigned long result = 0;
42 unsigned long bit = ( 1UL << ( ( 8 * sizeof ( bit ) ) - 2 ) );
43
44 while ( bit > value )
45 bit >>= 2;
46 while ( bit ) {
47 if ( value >= ( result + bit ) ) {
48 value -= ( result + bit );
49 result = ( ( result >> 1 ) + bit );
50 } else {
51 result >>= 1;
52 }
53 bit >>= 2;
54 }
55 return result;
56 }