/*
* Copyright (C) 2014 Michael Brown .
*
* 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 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/** @file
*
* Integer square root
*
*/
#include
/**
* Find integer square root
*
* @v value Value
* @v isqrt Integer square root of value
*/
unsigned long isqrt ( unsigned long value ) {
unsigned long result = 0;
unsigned long bit = ( 1UL << ( ( 8 * sizeof ( bit ) ) - 2 ) );
while ( bit > value )
bit >>= 2;
while ( bit ) {
if ( value >= ( result + bit ) ) {
value -= ( result + bit );
result = ( ( result >> 1 ) + bit );
} else {
result >>= 1;
}
bit >>= 2;
}
return result;
}