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1 /* $Id$ */ |
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2 |
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3 /** @file direction_func.h Different functions related to conversions between directions. */ |
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4 |
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5 #ifndef DIRECTION_FUNC_H |
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6 #define DIRECTION_FUNC_H |
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7 |
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8 #include "direction_type.h" |
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9 |
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10 /** |
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11 * Return the reverse of a direction |
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12 * |
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13 * @param d The direction to get the reverse from |
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14 * @return The reverse Direction |
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15 */ |
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16 static inline Direction ReverseDir(Direction d) |
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17 { |
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18 return (Direction)(4 ^ d); |
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19 } |
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20 |
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21 |
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22 /** |
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23 * Calculate the difference between to directions |
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24 * |
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25 * @param d0 The first direction as the base |
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26 * @param d1 The second direction as the offset from the base |
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27 * @return The difference how the second directions drifts of the first one. |
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28 */ |
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29 static inline DirDiff DirDifference(Direction d0, Direction d1) |
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30 { |
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31 return (DirDiff)((d0 + 8 - d1) % 8); |
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32 } |
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33 |
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34 /** |
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35 * Applies two differences together |
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36 * |
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37 * This function adds two differences together and return the resulting |
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38 * difference. So adding two DIRDIFF_REVERSE together results in the |
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39 * DIRDIFF_SAME difference. |
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40 * |
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41 * @param d The first difference |
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42 * @param delta The second difference to add on |
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43 * @return The resulting difference |
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44 */ |
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45 static inline DirDiff ChangeDirDiff(DirDiff d, DirDiff delta) |
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46 { |
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47 return (DirDiff)((d + delta) % 8); |
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48 } |
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49 |
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50 /** |
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51 * Change a direction by a given difference |
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52 * |
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53 * This functions returns a new direction of the given direction |
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54 * which is rotated by the given difference. |
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55 * |
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56 * @param d The direction to get a new direction from |
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57 * @param delta The offset/drift applied to the direction |
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58 * @return The new direction |
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59 */ |
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60 static inline Direction ChangeDir(Direction d, DirDiff delta) |
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61 { |
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62 return (Direction)((d + delta) % 8); |
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63 } |
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64 |
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65 |
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66 /** |
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67 * Returns the reverse direction of the given DiagDirection |
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68 * |
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69 * @param d The DiagDirection to get the reverse from |
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70 * @return The reverse direction |
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71 */ |
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72 static inline DiagDirection ReverseDiagDir(DiagDirection d) |
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73 { |
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74 return (DiagDirection)(2 ^ d); |
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75 } |
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76 |
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77 |
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78 /** |
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79 * Applies a difference on a DiagDirection |
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80 * |
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81 * This function applies a difference on a DiagDirection and returns |
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82 * the new DiagDirection. |
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83 * |
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84 * @param d The DiagDirection |
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85 * @param delta The difference to applie on |
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86 * @return The new direction which was calculated |
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87 */ |
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88 static inline DiagDirection ChangeDiagDir(DiagDirection d, DiagDirDiff delta) |
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89 { |
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90 return (DiagDirection)((d + delta) % 4); |
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91 } |
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92 |
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93 /** |
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94 * Convert a Direction to a DiagDirection. |
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95 * |
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96 * This function can be used to convert the 8-way Direction to |
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97 * the 4-way DiagDirection. If the direction cannot be mapped its |
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98 * "rounded clockwise". So DIR_N becomes DIAGDIR_NE. |
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99 * |
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100 * @param dir The direction to convert |
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101 * @return The resulting DiagDirection, maybe "rounded clockwise". |
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102 */ |
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103 static inline DiagDirection DirToDiagDir(Direction dir) |
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104 { |
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105 return (DiagDirection)(dir >> 1); |
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106 } |
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107 |
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108 /** |
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109 * Convert a DiagDirection to a Direction. |
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110 * |
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111 * This function can be used to convert the 4-way DiagDirection |
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112 * to the 8-way Direction. As 4-way are less than 8-way not all |
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113 * possible directions can be calculated. |
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114 * |
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115 * @param dir The direction to convert |
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116 * @return The resulting Direction |
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117 */ |
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118 static inline Direction DiagDirToDir(DiagDirection dir) |
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119 { |
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120 return (Direction)(dir * 2 + 1); |
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121 } |
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122 |
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123 |
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124 /** |
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125 * Select the other axis as provided. |
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126 * |
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127 * This is basically the not-operator for the axis. |
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128 * |
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129 * @param a The given axis |
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130 * @return The other axis |
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131 */ |
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132 static inline Axis OtherAxis(Axis a) |
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133 { |
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134 return (Axis)(a ^ 1); |
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135 } |
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136 |
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137 |
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138 /** |
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139 * Convert a DiagDirection to the axis. |
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140 * |
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141 * This function returns the axis which belongs to the given |
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142 * DiagDirection. The axis X belongs to the DiagDirection |
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143 * north-east and south-west. |
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144 * |
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145 * @param d The DiagDirection |
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146 * @return The axis which belongs to the direction |
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147 */ |
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148 static inline Axis DiagDirToAxis(DiagDirection d) |
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149 { |
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150 return (Axis)(d & 1); |
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151 } |
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152 |
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153 |
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154 /** |
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155 * Converts an Axis to a DiagDirection |
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156 * |
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157 * This function returns the DiagDirection which |
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158 * belongs to the axis. As 2 directions are mapped to an axis |
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159 * this function returns the one which points to south, |
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160 * either south-west (on X axis) or south-east (on Y axis) |
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161 * |
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162 * @param a The axis |
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163 * @return The direction pointed to south |
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164 */ |
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165 static inline DiagDirection AxisToDiagDir(Axis a) |
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166 { |
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167 return (DiagDirection)(2 - a); |
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168 } |
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169 |
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170 /** |
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171 * Convert an axis and a flag for north/south into a DiagDirection |
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172 * @param xy axis to convert |
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173 * @param ns north -> 0, south -> 1 |
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174 * @return the desired DiagDirection |
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175 */ |
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176 static inline DiagDirection XYNSToDiagDir(Axis xy, uint ns) |
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177 { |
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178 return (DiagDirection)(xy * 3 ^ ns * 2); |
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179 } |
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180 |
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181 /** |
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182 * Checks if an interger value is a valid DiagDirection |
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183 * |
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184 * @param d The value to check |
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185 * @return True if the value belongs to a DiagDirection, else false |
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186 */ |
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187 static inline bool IsValidDiagDirection(DiagDirection d) |
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188 { |
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189 return d < DIAGDIR_END; |
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190 } |
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191 |
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192 /** |
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193 * Checks if an integer value is a valid Direction |
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194 * |
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195 * @param d The value to check |
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196 * @return True if the value belongs to a Direction, else false |
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197 */ |
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198 static inline bool IsValidDirection(Direction d) |
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199 { |
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200 return d < DIR_END; |
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201 } |
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202 |
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203 /** |
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204 * Checks if an integer value is a valid Axis |
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205 * |
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206 * @param d The value to check |
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207 * @return True if the value belongs to an Axis, else false |
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208 */ |
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209 static inline bool IsValidAxis(Axis d) |
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210 { |
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211 return d < AXIS_END; |
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212 } |
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213 |
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214 #endif /* DIRECTION_H */ |