Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 1 | /* |
| 2 | Red Black Trees |
| 3 | (C) 1999 Andrea Arcangeli <andrea@suse.de> |
| 4 | (C) 2002 David Woodhouse <dwmw2@infradead.org> |
Harald Welte | e08da97 | 2017-11-13 01:00:26 +0900 | [diff] [blame] | 5 | |
| 6 | SPDX-License-Identifier: GPL-2.0+ |
| 7 | |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 8 | This program is free software; you can redistribute it and/or modify |
| 9 | it under the terms of the GNU General Public License as published by |
| 10 | the Free Software Foundation; either version 2 of the License, or |
| 11 | (at your option) any later version. |
| 12 | |
| 13 | This program is distributed in the hope that it will be useful, |
| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | GNU General Public License for more details. |
| 17 | |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 18 | linux/lib/rbtree.c |
| 19 | */ |
| 20 | |
| 21 | #include <osmocom/core/linuxrbtree.h> |
| 22 | |
| 23 | static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) |
| 24 | { |
| 25 | struct rb_node *right = node->rb_right; |
| 26 | struct rb_node *parent = rb_parent(node); |
| 27 | |
| 28 | if ((node->rb_right = right->rb_left)) |
| 29 | rb_set_parent(right->rb_left, node); |
| 30 | right->rb_left = node; |
| 31 | |
| 32 | rb_set_parent(right, parent); |
| 33 | |
| 34 | if (parent) |
| 35 | { |
| 36 | if (node == parent->rb_left) |
| 37 | parent->rb_left = right; |
| 38 | else |
| 39 | parent->rb_right = right; |
| 40 | } |
| 41 | else |
| 42 | root->rb_node = right; |
| 43 | rb_set_parent(node, right); |
| 44 | } |
| 45 | |
| 46 | static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) |
| 47 | { |
| 48 | struct rb_node *left = node->rb_left; |
| 49 | struct rb_node *parent = rb_parent(node); |
| 50 | |
| 51 | if ((node->rb_left = left->rb_right)) |
| 52 | rb_set_parent(left->rb_right, node); |
| 53 | left->rb_right = node; |
| 54 | |
| 55 | rb_set_parent(left, parent); |
| 56 | |
| 57 | if (parent) |
| 58 | { |
| 59 | if (node == parent->rb_right) |
| 60 | parent->rb_right = left; |
| 61 | else |
| 62 | parent->rb_left = left; |
| 63 | } |
| 64 | else |
| 65 | root->rb_node = left; |
| 66 | rb_set_parent(node, left); |
| 67 | } |
| 68 | |
| 69 | void rb_insert_color(struct rb_node *node, struct rb_root *root) |
| 70 | { |
| 71 | struct rb_node *parent, *gparent; |
| 72 | |
| 73 | while ((parent = rb_parent(node)) && rb_is_red(parent)) |
| 74 | { |
| 75 | gparent = rb_parent(parent); |
| 76 | |
| 77 | if (parent == gparent->rb_left) |
| 78 | { |
| 79 | { |
| 80 | register struct rb_node *uncle = gparent->rb_right; |
| 81 | if (uncle && rb_is_red(uncle)) |
| 82 | { |
| 83 | rb_set_black(uncle); |
| 84 | rb_set_black(parent); |
| 85 | rb_set_red(gparent); |
| 86 | node = gparent; |
| 87 | continue; |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | if (parent->rb_right == node) |
| 92 | { |
| 93 | register struct rb_node *tmp; |
| 94 | __rb_rotate_left(parent, root); |
| 95 | tmp = parent; |
| 96 | parent = node; |
| 97 | node = tmp; |
| 98 | } |
| 99 | |
| 100 | rb_set_black(parent); |
| 101 | rb_set_red(gparent); |
| 102 | __rb_rotate_right(gparent, root); |
| 103 | } else { |
| 104 | { |
| 105 | register struct rb_node *uncle = gparent->rb_left; |
| 106 | if (uncle && rb_is_red(uncle)) |
| 107 | { |
| 108 | rb_set_black(uncle); |
| 109 | rb_set_black(parent); |
| 110 | rb_set_red(gparent); |
| 111 | node = gparent; |
| 112 | continue; |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | if (parent->rb_left == node) |
| 117 | { |
| 118 | register struct rb_node *tmp; |
| 119 | __rb_rotate_right(parent, root); |
| 120 | tmp = parent; |
| 121 | parent = node; |
| 122 | node = tmp; |
| 123 | } |
| 124 | |
| 125 | rb_set_black(parent); |
| 126 | rb_set_red(gparent); |
| 127 | __rb_rotate_left(gparent, root); |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | rb_set_black(root->rb_node); |
| 132 | } |
| 133 | |
| 134 | static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, |
| 135 | struct rb_root *root) |
| 136 | { |
| 137 | struct rb_node *other; |
| 138 | |
| 139 | while ((!node || rb_is_black(node)) && node != root->rb_node) |
| 140 | { |
| 141 | if (parent->rb_left == node) |
| 142 | { |
| 143 | other = parent->rb_right; |
| 144 | if (rb_is_red(other)) |
| 145 | { |
| 146 | rb_set_black(other); |
| 147 | rb_set_red(parent); |
| 148 | __rb_rotate_left(parent, root); |
| 149 | other = parent->rb_right; |
| 150 | } |
| 151 | if ((!other->rb_left || rb_is_black(other->rb_left)) && |
| 152 | (!other->rb_right || rb_is_black(other->rb_right))) |
| 153 | { |
| 154 | rb_set_red(other); |
| 155 | node = parent; |
| 156 | parent = rb_parent(node); |
| 157 | } |
| 158 | else |
| 159 | { |
| 160 | if (!other->rb_right || rb_is_black(other->rb_right)) |
| 161 | { |
Sylvain Munaut | 0395c6e | 2011-11-11 15:25:25 +0100 | [diff] [blame] | 162 | rb_set_black(other->rb_left); |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 163 | rb_set_red(other); |
| 164 | __rb_rotate_right(other, root); |
| 165 | other = parent->rb_right; |
| 166 | } |
| 167 | rb_set_color(other, rb_color(parent)); |
| 168 | rb_set_black(parent); |
Sylvain Munaut | 0395c6e | 2011-11-11 15:25:25 +0100 | [diff] [blame] | 169 | rb_set_black(other->rb_right); |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 170 | __rb_rotate_left(parent, root); |
| 171 | node = root->rb_node; |
| 172 | break; |
| 173 | } |
| 174 | } |
| 175 | else |
| 176 | { |
| 177 | other = parent->rb_left; |
| 178 | if (rb_is_red(other)) |
| 179 | { |
| 180 | rb_set_black(other); |
| 181 | rb_set_red(parent); |
| 182 | __rb_rotate_right(parent, root); |
| 183 | other = parent->rb_left; |
| 184 | } |
| 185 | if ((!other->rb_left || rb_is_black(other->rb_left)) && |
| 186 | (!other->rb_right || rb_is_black(other->rb_right))) |
| 187 | { |
| 188 | rb_set_red(other); |
| 189 | node = parent; |
| 190 | parent = rb_parent(node); |
| 191 | } |
| 192 | else |
| 193 | { |
| 194 | if (!other->rb_left || rb_is_black(other->rb_left)) |
| 195 | { |
Sylvain Munaut | 0395c6e | 2011-11-11 15:25:25 +0100 | [diff] [blame] | 196 | rb_set_black(other->rb_right); |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 197 | rb_set_red(other); |
| 198 | __rb_rotate_left(other, root); |
| 199 | other = parent->rb_left; |
| 200 | } |
| 201 | rb_set_color(other, rb_color(parent)); |
| 202 | rb_set_black(parent); |
Sylvain Munaut | 0395c6e | 2011-11-11 15:25:25 +0100 | [diff] [blame] | 203 | rb_set_black(other->rb_left); |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 204 | __rb_rotate_right(parent, root); |
| 205 | node = root->rb_node; |
| 206 | break; |
| 207 | } |
| 208 | } |
| 209 | } |
| 210 | if (node) |
| 211 | rb_set_black(node); |
| 212 | } |
| 213 | |
| 214 | void rb_erase(struct rb_node *node, struct rb_root *root) |
| 215 | { |
| 216 | struct rb_node *child, *parent; |
| 217 | int color; |
| 218 | |
| 219 | if (!node->rb_left) |
| 220 | child = node->rb_right; |
| 221 | else if (!node->rb_right) |
| 222 | child = node->rb_left; |
| 223 | else |
| 224 | { |
| 225 | struct rb_node *old = node, *left; |
| 226 | |
| 227 | node = node->rb_right; |
| 228 | while ((left = node->rb_left) != NULL) |
| 229 | node = left; |
Sylvain Munaut | b8c5bde | 2011-11-11 15:28:01 +0100 | [diff] [blame] | 230 | |
| 231 | if (rb_parent(old)) { |
| 232 | if (rb_parent(old)->rb_left == old) |
| 233 | rb_parent(old)->rb_left = node; |
| 234 | else |
| 235 | rb_parent(old)->rb_right = node; |
| 236 | } else |
| 237 | root->rb_node = node; |
| 238 | |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 239 | child = node->rb_right; |
| 240 | parent = rb_parent(node); |
| 241 | color = rb_color(node); |
| 242 | |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 243 | if (parent == old) { |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 244 | parent = node; |
Sylvain Munaut | a83cbe1 | 2011-11-11 15:29:59 +0100 | [diff] [blame] | 245 | } else { |
| 246 | if (child) |
| 247 | rb_set_parent(child, parent); |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 248 | parent->rb_left = child; |
Sylvain Munaut | 54187ba | 2011-11-11 15:31:01 +0100 | [diff] [blame] | 249 | |
| 250 | node->rb_right = old->rb_right; |
| 251 | rb_set_parent(old->rb_right, node); |
Sylvain Munaut | a83cbe1 | 2011-11-11 15:29:59 +0100 | [diff] [blame] | 252 | } |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 253 | |
| 254 | node->rb_parent_color = old->rb_parent_color; |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 255 | node->rb_left = old->rb_left; |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 256 | rb_set_parent(old->rb_left, node); |
Sylvain Munaut | 54187ba | 2011-11-11 15:31:01 +0100 | [diff] [blame] | 257 | |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 258 | goto color; |
| 259 | } |
| 260 | |
| 261 | parent = rb_parent(node); |
| 262 | color = rb_color(node); |
| 263 | |
| 264 | if (child) |
| 265 | rb_set_parent(child, parent); |
| 266 | if (parent) |
| 267 | { |
| 268 | if (parent->rb_left == node) |
| 269 | parent->rb_left = child; |
| 270 | else |
| 271 | parent->rb_right = child; |
| 272 | } |
| 273 | else |
| 274 | root->rb_node = child; |
| 275 | |
| 276 | color: |
| 277 | if (color == RB_BLACK) |
| 278 | __rb_erase_color(child, parent, root); |
| 279 | } |
| 280 | |
| 281 | /* |
| 282 | * This function returns the first node (in sort order) of the tree. |
| 283 | */ |
Sylvain Munaut | 2179f40 | 2011-11-11 15:32:57 +0100 | [diff] [blame] | 284 | struct rb_node *rb_first(const struct rb_root *root) |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 285 | { |
| 286 | struct rb_node *n; |
| 287 | |
| 288 | n = root->rb_node; |
| 289 | if (!n) |
| 290 | return NULL; |
| 291 | while (n->rb_left) |
| 292 | n = n->rb_left; |
| 293 | return n; |
| 294 | } |
| 295 | |
Sylvain Munaut | 2179f40 | 2011-11-11 15:32:57 +0100 | [diff] [blame] | 296 | struct rb_node *rb_last(const struct rb_root *root) |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 297 | { |
| 298 | struct rb_node *n; |
| 299 | |
| 300 | n = root->rb_node; |
| 301 | if (!n) |
| 302 | return NULL; |
| 303 | while (n->rb_right) |
| 304 | n = n->rb_right; |
| 305 | return n; |
| 306 | } |
| 307 | |
Sylvain Munaut | 2179f40 | 2011-11-11 15:32:57 +0100 | [diff] [blame] | 308 | struct rb_node *rb_next(const struct rb_node *node) |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 309 | { |
| 310 | struct rb_node *parent; |
| 311 | |
| 312 | if (rb_parent(node) == node) |
| 313 | return NULL; |
| 314 | |
| 315 | /* If we have a right-hand child, go down and then left as far |
| 316 | as we can. */ |
| 317 | if (node->rb_right) { |
| 318 | node = node->rb_right; |
| 319 | while (node->rb_left) |
| 320 | node=node->rb_left; |
Sylvain Munaut | 2179f40 | 2011-11-11 15:32:57 +0100 | [diff] [blame] | 321 | return (struct rb_node *)node; |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 322 | } |
| 323 | |
| 324 | /* No right-hand children. Everything down and left is |
| 325 | smaller than us, so any 'next' node must be in the general |
| 326 | direction of our parent. Go up the tree; any time the |
| 327 | ancestor is a right-hand child of its parent, keep going |
| 328 | up. First time it's a left-hand child of its parent, said |
| 329 | parent is our 'next' node. */ |
| 330 | while ((parent = rb_parent(node)) && node == parent->rb_right) |
| 331 | node = parent; |
| 332 | |
| 333 | return parent; |
| 334 | } |
| 335 | |
Sylvain Munaut | 2179f40 | 2011-11-11 15:32:57 +0100 | [diff] [blame] | 336 | struct rb_node *rb_prev(const struct rb_node *node) |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 337 | { |
| 338 | struct rb_node *parent; |
| 339 | |
| 340 | if (rb_parent(node) == node) |
| 341 | return NULL; |
| 342 | |
| 343 | /* If we have a left-hand child, go down and then right as far |
| 344 | as we can. */ |
| 345 | if (node->rb_left) { |
| 346 | node = node->rb_left; |
| 347 | while (node->rb_right) |
| 348 | node=node->rb_right; |
Sylvain Munaut | 2179f40 | 2011-11-11 15:32:57 +0100 | [diff] [blame] | 349 | return (struct rb_node *)node; |
Pablo Neira Ayuso | f74db0b | 2011-09-26 11:44:57 +0200 | [diff] [blame] | 350 | } |
| 351 | |
| 352 | /* No left-hand children. Go up till we find an ancestor which |
| 353 | is a right-hand child of its parent */ |
| 354 | while ((parent = rb_parent(node)) && node == parent->rb_left) |
| 355 | node = parent; |
| 356 | |
| 357 | return parent; |
| 358 | } |
| 359 | |
| 360 | void rb_replace_node(struct rb_node *victim, struct rb_node *new, |
| 361 | struct rb_root *root) |
| 362 | { |
| 363 | struct rb_node *parent = rb_parent(victim); |
| 364 | |
| 365 | /* Set the surrounding nodes to point to the replacement */ |
| 366 | if (parent) { |
| 367 | if (victim == parent->rb_left) |
| 368 | parent->rb_left = new; |
| 369 | else |
| 370 | parent->rb_right = new; |
| 371 | } else { |
| 372 | root->rb_node = new; |
| 373 | } |
| 374 | if (victim->rb_left) |
| 375 | rb_set_parent(victim->rb_left, new); |
| 376 | if (victim->rb_right) |
| 377 | rb_set_parent(victim->rb_right, new); |
| 378 | |
| 379 | /* Copy the pointers/colour from the victim to the replacement */ |
| 380 | *new = *victim; |
| 381 | } |