From da330c5975b9f565d059ef8084dfdacc20f34246 Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Wed, 26 Oct 2011 22:49:11 -0700 Subject: altos: Bring up basic TeleTerra v0.2 UI Lots of fun stuff here -- multiple panes of information. Signed-off-by: Keith Packard --- src/core/ao_sqrt.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 src/core/ao_sqrt.c (limited to 'src/core/ao_sqrt.c') diff --git a/src/core/ao_sqrt.c b/src/core/ao_sqrt.c new file mode 100644 index 00000000..09c2e319 --- /dev/null +++ b/src/core/ao_sqrt.c @@ -0,0 +1,46 @@ +/* + * Copyright © 2011 Keith Packard + * + * 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; version 2 of the License. + * + * 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., + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. + */ + +#include "ao.h" + +/* Adapted from int_sqrt.c in the linux kernel, which is licensed GPLv2 */ +/** + * int_sqrt - rough approximation to sqrt + * @x: integer of which to calculate the sqrt + * + * A very rough approximation to the sqrt() function. + */ + +uint32_t +ao_sqrt(uint32_t op) +{ + uint32_t res = 0; + uint32_t one = 1UL << (sizeof (one) * 8 - 2); + + while (one > op) + one >>= 2; + + while (one != 0) { + if (op >= res + one) { + op = op - (res + one); + res = res + 2 * one; + } + res /= 2; + one /= 4; + } + return res; +} -- cgit v1.2.3