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5056 | serge | 1 | /* |
2 | Interval Trees |
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3 | (C) 2012 Michel Lespinasse |
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4 | |||
5 | This program is free software; you can redistribute it and/or modify |
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6 | it under the terms of the GNU General Public License as published by |
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7 | the Free Software Foundation; either version 2 of the License, or |
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8 | (at your option) any later version. |
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9 | |||
10 | This program is distributed in the hope that it will be useful, |
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11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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13 | GNU General Public License for more details. |
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14 | |||
15 | You should have received a copy of the GNU General Public License |
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16 | along with this program; if not, write to the Free Software |
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17 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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18 | |||
19 | include/linux/interval_tree_generic.h |
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20 | */ |
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21 | |||
22 | #include |
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23 | |||
24 | /* |
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25 | * Template for implementing interval trees |
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26 | * |
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27 | * ITSTRUCT: struct type of the interval tree nodes |
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28 | * ITRB: name of struct rb_node field within ITSTRUCT |
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29 | * ITTYPE: type of the interval endpoints |
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30 | * ITSUBTREE: name of ITTYPE field within ITSTRUCT holding last-in-subtree |
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31 | * ITSTART(n): start endpoint of ITSTRUCT node n |
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32 | * ITLAST(n): last endpoint of ITSTRUCT node n |
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33 | * ITSTATIC: 'static' or empty |
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34 | * ITPREFIX: prefix to use for the inline tree definitions |
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35 | * |
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36 | * Note - before using this, please consider if non-generic version |
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37 | * (interval_tree.h) would work for you... |
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38 | */ |
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39 | |||
40 | #define INTERVAL_TREE_DEFINE(ITSTRUCT, ITRB, ITTYPE, ITSUBTREE, \ |
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41 | ITSTART, ITLAST, ITSTATIC, ITPREFIX) \ |
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42 | \ |
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43 | /* Callbacks for augmented rbtree insert and remove */ \ |
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44 | \ |
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45 | static inline ITTYPE ITPREFIX ## _compute_subtree_last(ITSTRUCT *node) \ |
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46 | { \ |
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47 | ITTYPE max = ITLAST(node), subtree_last; \ |
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48 | if (node->ITRB.rb_left) { \ |
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49 | subtree_last = rb_entry(node->ITRB.rb_left, \ |
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50 | ITSTRUCT, ITRB)->ITSUBTREE; \ |
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51 | if (max < subtree_last) \ |
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52 | max = subtree_last; \ |
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53 | } \ |
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54 | if (node->ITRB.rb_right) { \ |
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55 | subtree_last = rb_entry(node->ITRB.rb_right, \ |
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56 | ITSTRUCT, ITRB)->ITSUBTREE; \ |
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57 | if (max < subtree_last) \ |
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58 | max = subtree_last; \ |
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59 | } \ |
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60 | return max; \ |
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61 | } \ |
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62 | \ |
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63 | RB_DECLARE_CALLBACKS(static, ITPREFIX ## _augment, ITSTRUCT, ITRB, \ |
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64 | ITTYPE, ITSUBTREE, ITPREFIX ## _compute_subtree_last) \ |
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65 | \ |
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66 | /* Insert / remove interval nodes from the tree */ \ |
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67 | \ |
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68 | ITSTATIC void ITPREFIX ## _insert(ITSTRUCT *node, struct rb_root *root) \ |
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69 | { \ |
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70 | struct rb_node **link = &root->rb_node, *rb_parent = NULL; \ |
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71 | ITTYPE start = ITSTART(node), last = ITLAST(node); \ |
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72 | ITSTRUCT *parent; \ |
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73 | \ |
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74 | while (*link) { \ |
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75 | rb_parent = *link; \ |
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76 | parent = rb_entry(rb_parent, ITSTRUCT, ITRB); \ |
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77 | if (parent->ITSUBTREE < last) \ |
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78 | parent->ITSUBTREE = last; \ |
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79 | if (start < ITSTART(parent)) \ |
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80 | link = &parent->ITRB.rb_left; \ |
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81 | else \ |
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82 | link = &parent->ITRB.rb_right; \ |
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83 | } \ |
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84 | \ |
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85 | node->ITSUBTREE = last; \ |
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86 | rb_link_node(&node->ITRB, rb_parent, link); \ |
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87 | rb_insert_augmented(&node->ITRB, root, &ITPREFIX ## _augment); \ |
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88 | } \ |
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89 | \ |
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90 | ITSTATIC void ITPREFIX ## _remove(ITSTRUCT *node, struct rb_root *root) \ |
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91 | { \ |
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92 | rb_erase_augmented(&node->ITRB, root, &ITPREFIX ## _augment); \ |
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93 | } \ |
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94 | \ |
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95 | /* \ |
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96 | * Iterate over intervals intersecting [start;last] \ |
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97 | * \ |
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98 | * Note that a node's interval intersects [start;last] iff: \ |
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99 | * Cond1: ITSTART(node) <= last \ |
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100 | * and \ |
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101 | * Cond2: start <= ITLAST(node) \ |
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102 | */ \ |
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103 | \ |
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104 | static ITSTRUCT * \ |
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105 | ITPREFIX ## _subtree_search(ITSTRUCT *node, ITTYPE start, ITTYPE last) \ |
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106 | { \ |
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107 | while (true) { \ |
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108 | /* \ |
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109 | * Loop invariant: start <= node->ITSUBTREE \ |
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110 | * (Cond2 is satisfied by one of the subtree nodes) \ |
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111 | */ \ |
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112 | if (node->ITRB.rb_left) { \ |
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113 | ITSTRUCT *left = rb_entry(node->ITRB.rb_left, \ |
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114 | ITSTRUCT, ITRB); \ |
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115 | if (start <= left->ITSUBTREE) { \ |
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116 | /* \ |
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117 | * Some nodes in left subtree satisfy Cond2. \ |
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118 | * Iterate to find the leftmost such node N. \ |
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119 | * If it also satisfies Cond1, that's the \ |
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120 | * match we are looking for. Otherwise, there \ |
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121 | * is no matching interval as nodes to the \ |
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122 | * right of N can't satisfy Cond1 either. \ |
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123 | */ \ |
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124 | node = left; \ |
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125 | continue; \ |
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126 | } \ |
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127 | } \ |
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128 | if (ITSTART(node) <= last) { /* Cond1 */ \ |
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129 | if (start <= ITLAST(node)) /* Cond2 */ \ |
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130 | return node; /* node is leftmost match */ \ |
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131 | if (node->ITRB.rb_right) { \ |
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132 | node = rb_entry(node->ITRB.rb_right, \ |
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133 | ITSTRUCT, ITRB); \ |
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134 | if (start <= node->ITSUBTREE) \ |
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135 | continue; \ |
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136 | } \ |
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137 | } \ |
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138 | return NULL; /* No match */ \ |
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139 | } \ |
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140 | } \ |
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141 | \ |
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142 | ITSTATIC ITSTRUCT * \ |
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143 | ITPREFIX ## _iter_first(struct rb_root *root, ITTYPE start, ITTYPE last) \ |
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144 | { \ |
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145 | ITSTRUCT *node; \ |
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146 | \ |
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147 | if (!root->rb_node) \ |
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148 | return NULL; \ |
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149 | node = rb_entry(root->rb_node, ITSTRUCT, ITRB); \ |
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150 | if (node->ITSUBTREE < start) \ |
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151 | return NULL; \ |
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152 | return ITPREFIX ## _subtree_search(node, start, last); \ |
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153 | } \ |
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154 | \ |
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155 | ITSTATIC ITSTRUCT * \ |
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156 | ITPREFIX ## _iter_next(ITSTRUCT *node, ITTYPE start, ITTYPE last) \ |
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157 | { \ |
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158 | struct rb_node *rb = node->ITRB.rb_right, *prev; \ |
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159 | \ |
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160 | while (true) { \ |
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161 | /* \ |
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162 | * Loop invariants: \ |
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163 | * Cond1: ITSTART(node) <= last \ |
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164 | * rb == node->ITRB.rb_right \ |
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165 | * \ |
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166 | * First, search right subtree if suitable \ |
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167 | */ \ |
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168 | if (rb) { \ |
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169 | ITSTRUCT *right = rb_entry(rb, ITSTRUCT, ITRB); \ |
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170 | if (start <= right->ITSUBTREE) \ |
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171 | return ITPREFIX ## _subtree_search(right, \ |
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172 | start, last); \ |
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173 | } \ |
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174 | \ |
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175 | /* Move up the tree until we come from a node's left child */ \ |
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176 | do { \ |
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177 | rb = rb_parent(&node->ITRB); \ |
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178 | if (!rb) \ |
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179 | return NULL; \ |
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180 | prev = &node->ITRB; \ |
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181 | node = rb_entry(rb, ITSTRUCT, ITRB); \ |
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182 | rb = node->ITRB.rb_right; \ |
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183 | } while (prev == rb); \ |
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184 | \ |
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185 | /* Check if the node intersects [start;last] */ \ |
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186 | if (last < ITSTART(node)) /* !Cond1 */ \ |
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187 | return NULL; \ |
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188 | else if (start <= ITLAST(node)) /* Cond2 */ \ |
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189 | return node; \ |
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190 | } \ |
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191 | }=>>=>=>>=>=>=>=>=>=>=>>>>> |