source: libcaca/trunk/libee/math.c @ 171

Last change on this file since 171 was 171, checked in by Sam Hocevar, 19 years ago
  • libee/math.c: + ee_sqrt() now uses unsigned ints. + Avoid overflows in ee_sqrt().
  • Property svn:keywords set to Id
File size: 1.6 KB
Line 
1/*
2 *   libee         ASCII-Art library
3 *   Copyright (c) 2002, 2003 Sam Hocevar <sam@zoy.org>
4 *                 All Rights Reserved
5 *
6 *   $Id: math.c 171 2003-11-14 16:55:58Z sam $
7 *
8 *   This program is free software; you can redistribute it and/or modify
9 *   it under the terms of the GNU General Public License as published by
10 *   the Free Software Foundation; either version 2 of the License, or
11 *   (at your option) any later version.
12 *
13 *   This program is distributed in the hope that it will be useful,
14 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
15 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 *   GNU General Public License for more details.
17 *
18 *   You should have received a copy of the GNU General Public License
19 *   along with this program; if not, write to the Free Software
20 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23#include "config.h"
24
25#include <stdlib.h>
26
27#include "ee.h"
28#include "ee_internals.h"
29
30int ee_rand(int min, int max)
31{
32    return min + (int)((1.0*(max-min+1)) * rand() / (RAND_MAX+1.0));
33}
34
35unsigned int ee_sqrt(unsigned int a)
36{
37    if(a == 0)
38        return 0;
39
40    if(a < 1000000000)
41    {
42        unsigned int x = a < 10 ? 1
43                       : a < 1000 ? 10
44                       : a < 100000 ? 100
45                       : a < 10000000 ? 1000
46                       : 10000;
47
48        /* Newton's method. Three iterations would be more than enough. */
49        x = (x * x + a) / x / 2;
50        x = (x * x + a) / x / 2;
51        x = (x * x + a) / x / 2;
52        x = (x * x + a) / x / 2;
53
54        return x;
55    }
56
57    return 2 * ee_sqrt(a / 4);
58}
59
Note: See TracBrowser for help on using the repository browser.