source: libcaca/trunk/cucul/math.c @ 769

Last change on this file since 769 was 769, checked in by Sam Hocevar, 14 years ago
  • Removed \file directives from all files except caca.h and cucul.h, to remove redundencies in the Doxygen documentation.
  • Property svn:keywords set to Id
File size: 1.7 KB
RevLine 
[89]1/*
[672]2 *  libcucul      Canvas for ultrafast compositing of Unicode letters
[527]3 *  Copyright (c) 2002-2006 Sam Hocevar <sam@zoy.org>
[268]4 *                All Rights Reserved
[89]5 *
[769]6 *  $Id: math.c 769 2006-04-14 07:30:53Z sam $
7 *
[268]8 *  This library is free software; you can redistribute it and/or
[522]9 *  modify it under the terms of the Do What The Fuck You Want To
10 *  Public License, Version 2, as published by Sam Hocevar. See
11 *  http://sam.zoy.org/wtfpl/COPYING for more details.
[89]12 */
13
[769]14/*
[268]15 *  This file contains simple mathematical routines.
[205]16 */
17
[89]18#include "config.h"
19
[568]20#if !defined(__KERNEL__)
21#   include <stdlib.h>
22#endif
[89]23
[524]24#include "cucul.h"
25#include "cucul_internals.h"
[89]26
[257]27/**
28 * \brief Generate a random integer within a range.
29 *
30 * \param min The lower bound of the integer range.
31 * \param max The upper bound of the integer range.
32 * \return A random integer comprised between \p min and \p max, inclusive.
33 */
[524]34int cucul_rand(int min, int max)
[89]35{
[91]36    return min + (int)((1.0*(max-min+1)) * rand() / (RAND_MAX+1.0));
[89]37}
38
[257]39/**
40 * \brief Approximate a square root, using Newton's method to avoid
41 *        costly floating point calculations.
42 *
43 * \param a A positive integer.
44 * \return The approximate square root of \p a.
45 */
[524]46unsigned int cucul_sqrt(unsigned int a)
[89]47{
[171]48    if(a == 0)
49        return 0;
[89]50
[171]51    if(a < 1000000000)
[89]52    {
[171]53        unsigned int x = a < 10 ? 1
54                       : a < 1000 ? 10
55                       : a < 100000 ? 100
56                       : a < 10000000 ? 1000
57                       : 10000;
[89]58
[171]59        /* Newton's method. Three iterations would be more than enough. */
60        x = (x * x + a) / x / 2;
61        x = (x * x + a) / x / 2;
62        x = (x * x + a) / x / 2;
63        x = (x * x + a) / x / 2;
[89]64
[171]65        return x;
66    }
[89]67
[524]68    return 2 * cucul_sqrt(a / 4);
[89]69}
70
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