1 | // |
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2 | // Lol Engine |
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3 | // |
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4 | // Copyright: (c) 2010-2013 Sam Hocevar <sam@hocevar.net> |
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5 | // This program is free software; you can redistribute it and/or |
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6 | // modify it under the terms of the Do What The Fuck You Want To |
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7 | // Public License, Version 2, as published by Sam Hocevar. See |
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8 | // http://www.wtfpl.net/ for more details. |
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9 | // |
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10 | |
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11 | // |
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12 | // The Random number generators |
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13 | // ---------------------------- |
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14 | // |
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15 | |
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16 | #if !defined __LOL_MATH_RAND_H__ |
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17 | #define __LOL_MATH_RAND_H__ |
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18 | |
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19 | #include <cstdlib> |
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20 | #include <stdint.h> |
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21 | |
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22 | namespace lol |
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23 | { |
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24 | |
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25 | /* Random number generators */ |
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26 | template<typename T> static inline T rand(); |
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27 | template<typename T> static inline T rand(T a); |
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28 | template<typename T> static inline T rand(T a, T b); |
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29 | |
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30 | /* One-value random number generators */ |
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31 | template<typename T> static inline T rand(T a) |
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32 | { |
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33 | return rand<T>() % a; |
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34 | } |
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35 | |
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36 | template<> inline half rand<half>(half a) |
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37 | { |
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38 | float f = (float)std::rand() / (float)RAND_MAX; |
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39 | return (half)(a * f); |
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40 | } |
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41 | |
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42 | template<> inline float rand<float>(float a) |
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43 | { |
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44 | float f = (float)std::rand() / (float)RAND_MAX; |
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45 | return a * f; |
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46 | } |
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47 | |
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48 | template<> inline double rand<double>(double a) |
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49 | { |
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50 | double f = (double)std::rand() / (double)RAND_MAX; |
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51 | return a * f; |
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52 | } |
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53 | |
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54 | template<> inline ldouble rand<ldouble>(ldouble a) |
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55 | { |
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56 | ldouble f = (ldouble)std::rand() / (ldouble)RAND_MAX; |
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57 | return a * f; |
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58 | } |
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59 | |
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60 | /* Two-value random number generator -- no need for specialisation */ |
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61 | template<typename T> static inline T rand(T a, T b) |
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62 | { |
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63 | return a + rand<T>(b - a); |
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64 | } |
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65 | |
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66 | /* Default random number generator */ |
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67 | template<typename T> static inline T rand() |
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68 | { |
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69 | switch (sizeof(T)) |
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70 | { |
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71 | case 1: |
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72 | return static_cast<T>(std::rand() & 0x7f); |
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73 | case 2: |
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74 | { |
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75 | uint16_t ret = std::rand(); |
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76 | if (RAND_MAX < 0x7fff) |
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77 | ret = (ret << 7) ^ std::rand(); |
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78 | return static_cast<T>(ret & 0x7fffu); |
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79 | } |
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80 | case 4: |
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81 | { |
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82 | uint32_t ret = std::rand(); |
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83 | if (RAND_MAX >= 0xffff) |
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84 | ret = (ret << 16) ^ std::rand(); |
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85 | else |
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86 | { |
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87 | ret = (ret << 8) ^ std::rand(); |
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88 | ret = (ret << 8) ^ std::rand(); |
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89 | ret = (ret << 8) ^ std::rand(); |
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90 | } |
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91 | return static_cast<T>(ret & 0x7fffffffu); |
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92 | } |
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93 | case 8: |
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94 | { |
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95 | uint64_t ret = std::rand(); |
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96 | if (RAND_MAX >= 0xffff) |
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97 | { |
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98 | ret = (ret << 16) ^ std::rand(); |
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99 | ret = (ret << 16) ^ std::rand(); |
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100 | ret = (ret << 16) ^ std::rand(); |
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101 | } |
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102 | else |
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103 | { |
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104 | ret = (ret << 8) ^ std::rand(); |
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105 | ret = (ret << 8) ^ std::rand(); |
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106 | ret = (ret << 8) ^ std::rand(); |
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107 | ret = (ret << 8) ^ std::rand(); |
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108 | ret = (ret << 8) ^ std::rand(); |
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109 | ret = (ret << 8) ^ std::rand(); |
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110 | ret = (ret << 8) ^ std::rand(); |
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111 | } |
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112 | return static_cast<T>(ret & (~(uint64_t)0 >> 1)); |
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113 | } |
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114 | default: |
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115 | ASSERT(false, "rand() doesn’t support types of size %d\n", |
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116 | (int)sizeof(T)); |
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117 | return 0; |
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118 | } |
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119 | } |
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120 | |
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121 | template<> inline half rand<half>() { return rand<half>(1.f); } |
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122 | template<> inline float rand<float>() { return rand<float>(1.f); } |
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123 | template<> inline double rand<double>() { return rand<double>(1.0); } |
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124 | template<> inline ldouble rand<ldouble>() { return rand<ldouble>(1.0); } |
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125 | |
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126 | } /* namespace lol */ |
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127 | |
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128 | #endif // __LOL_MATH_RAND_H__ |
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129 | |
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