1 | /* |
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2 | * libcaca ASCII-Art library |
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3 | * Copyright (c) 2002, 2003 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 GNU Lesser General Public |
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8 | * License as published by the Free Software Foundation; either |
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9 | * version 2 of the License, or (at your option) any later version. |
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10 | * |
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11 | * This library is distributed in the hope that it will be useful, |
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12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 | * Lesser General Public License for more details. |
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15 | * |
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16 | * You should have received a copy of the GNU Lesser General Public |
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17 | * License along with this library; if not, write to the Free Software |
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18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
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19 | * 02111-1307 USA |
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20 | */ |
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21 | |
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22 | /** \file math.c |
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23 | * \version \$Id: math.c 298 2003-12-31 14:21:08Z sam $ |
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24 | * \author Sam Hocevar <sam@zoy.org> |
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25 | * \brief Math |
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26 | * |
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27 | * This file contains simple mathematical routines. |
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28 | */ |
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29 | |
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30 | #include "config.h" |
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31 | |
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32 | #include <stdlib.h> |
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33 | |
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34 | #include "caca.h" |
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35 | #include "caca_internals.h" |
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36 | |
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37 | /** |
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38 | * \brief Generate a random integer within a range. |
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39 | * |
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40 | * \param min The lower bound of the integer range. |
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41 | * \param max The upper bound of the integer range. |
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42 | * \return A random integer comprised between \p min and \p max, inclusive. |
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43 | */ |
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44 | int caca_rand(int min, int max) |
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45 | { |
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46 | return min + (int)((1.0*(max-min+1)) * rand() / (RAND_MAX+1.0)); |
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47 | } |
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48 | |
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49 | /** |
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50 | * \brief Approximate a square root, using Newton's method to avoid |
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51 | * costly floating point calculations. |
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52 | * |
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53 | * \param a A positive integer. |
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54 | * \return The approximate square root of \p a. |
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55 | */ |
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56 | unsigned int caca_sqrt(unsigned int a) |
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57 | { |
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58 | if(a == 0) |
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59 | return 0; |
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60 | |
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61 | if(a < 1000000000) |
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62 | { |
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63 | unsigned int x = a < 10 ? 1 |
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64 | : a < 1000 ? 10 |
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65 | : a < 100000 ? 100 |
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66 | : a < 10000000 ? 1000 |
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67 | : 10000; |
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68 | |
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69 | /* Newton's method. Three iterations would be more than enough. */ |
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70 | x = (x * x + a) / x / 2; |
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71 | x = (x * x + a) / x / 2; |
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72 | x = (x * x + a) / x / 2; |
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73 | x = (x * x + a) / x / 2; |
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74 | |
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75 | return x; |
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76 | } |
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77 | |
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78 | return 2 * caca_sqrt(a / 4); |
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79 | } |
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80 | |
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