1 | /* |
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2 | * libcucul Unicode canvas library |
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3 | * Copyright (c) 2002-2006 Sam Hocevar <sam@zoy.org> |
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4 | * All Rights Reserved |
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5 | * |
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6 | * This library is free software; you can redistribute it and/or |
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7 | * modify it under the terms of the Do What The Fuck You Want To |
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8 | * Public License, Version 2, as published by Sam Hocevar. See |
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9 | * http://sam.zoy.org/wtfpl/COPYING for more details. |
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10 | */ |
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11 | |
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12 | /** \file math.c |
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13 | * \version \$Id: math.c 540 2006-03-07 09:17:35Z sam $ |
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14 | * \author Sam Hocevar <sam@zoy.org> |
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15 | * \brief Math |
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16 | * |
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17 | * This file contains simple mathematical routines. |
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18 | */ |
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19 | |
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20 | #include "config.h" |
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21 | |
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22 | #include <stdlib.h> |
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23 | |
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24 | #include "cucul.h" |
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25 | #include "cucul_internals.h" |
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26 | |
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27 | /** |
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28 | * \brief Generate a random integer within a range. |
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29 | * |
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30 | * \param min The lower bound of the integer range. |
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31 | * \param max The upper bound of the integer range. |
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32 | * \return A random integer comprised between \p min and \p max, inclusive. |
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33 | */ |
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34 | int cucul_rand(int min, int max) |
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35 | { |
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36 | return min + (int)((1.0*(max-min+1)) * rand() / (RAND_MAX+1.0)); |
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37 | } |
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38 | |
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39 | /** |
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40 | * \brief Approximate a square root, using Newton's method to avoid |
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41 | * costly floating point calculations. |
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42 | * |
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43 | * \param a A positive integer. |
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44 | * \return The approximate square root of \p a. |
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45 | */ |
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46 | unsigned int cucul_sqrt(unsigned int a) |
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47 | { |
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48 | if(a == 0) |
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49 | return 0; |
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50 | |
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51 | if(a < 1000000000) |
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52 | { |
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53 | unsigned int x = a < 10 ? 1 |
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54 | : a < 1000 ? 10 |
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55 | : a < 100000 ? 100 |
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56 | : a < 10000000 ? 1000 |
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57 | : 10000; |
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58 | |
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59 | /* Newton's method. Three iterations would be more than enough. */ |
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60 | x = (x * x + a) / x / 2; |
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61 | x = (x * x + a) / x / 2; |
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62 | x = (x * x + a) / x / 2; |
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63 | x = (x * x + a) / x / 2; |
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64 | |
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65 | return x; |
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66 | } |
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67 | |
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68 | return 2 * cucul_sqrt(a / 4); |
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69 | } |
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70 | |
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71 | |
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72 | /** |
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73 | * \brief powf substitute (x^y) |
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74 | * \param x The value to be raised |
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75 | * \param y The power to raise x of. |
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76 | * \return \p x raised to the power of \p y |
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77 | */ |
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78 | |
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79 | float cucul_powf(float x, float y) |
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80 | { |
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81 | int i=((int)y); |
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82 | float r=x; |
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83 | |
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84 | if(((int)y)==1 || ((int)x)==1) |
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85 | return x; |
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86 | |
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87 | i--; |
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88 | while(i--) |
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89 | { |
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90 | r*=x; |
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91 | } |
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92 | return r; |
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93 | } |
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