1 /* 2 Red Black Trees 3 (C) 1999 Andrea Arcangeli <andrea (at) suse.de> 4 (C) 2002 David Woodhouse <dwmw2 (at) infradead.org> 5 6 This program is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2 of the License, or 9 (at your option) any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program; if not, write to the Free Software 18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19 20 linux/lib/rbtree.c 21 */ 22 23 #include "../include/linux/rbtree.h" 24 #include "../include/linux/module.h" 25 26 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) 27 { 28 struct rb_node *right = node->rb_right; 29 struct rb_node *parent = rb_parent(node); 30 31 if ((node->rb_right = right->rb_left)) 32 rb_set_parent(right->rb_left, node); 33 right->rb_left = node; 34 35 rb_set_parent(right, parent); 36 37 if (parent) 38 { 39 if (node == parent->rb_left) 40 parent->rb_left = right; 41 else 42 parent->rb_right = right; 43 } 44 else 45 root->rb_node = right; 46 rb_set_parent(node, right); 47 } 48 49 static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) 50 { 51 struct rb_node *left = node->rb_left; 52 struct rb_node *parent = rb_parent(node); 53 54 if ((node->rb_left = left->rb_right)) 55 rb_set_parent(left->rb_right, node); 56 left->rb_right = node; 57 58 rb_set_parent(left, parent); 59 60 if (parent) 61 { 62 if (node == parent->rb_right) 63 parent->rb_right = left; 64 else 65 parent->rb_left = left; 66 } 67 else 68 root->rb_node = left; 69 rb_set_parent(node, left); 70 } 71 72 void rb_insert_color(struct rb_node *node, struct rb_root *root) 73 { 74 struct rb_node *parent, *gparent; 75 76 while ((parent = rb_parent(node)) && rb_is_red(parent)) 77 { 78 gparent = rb_parent(parent); 79 80 if (parent == gparent->rb_left) 81 { 82 { 83 register struct rb_node *uncle = gparent->rb_right; 84 if (uncle && rb_is_red(uncle)) 85 { 86 rb_set_black(uncle); 87 rb_set_black(parent); 88 rb_set_red(gparent); 89 node = gparent; 90 continue; 91 } 92 } 93 94 if (parent->rb_right == node) 95 { 96 register struct rb_node *tmp; 97 __rb_rotate_left(parent, root); 98 tmp = parent; 99 parent = node; 100 node = tmp; 101 } 102 103 rb_set_black(parent); 104 rb_set_red(gparent); 105 __rb_rotate_right(gparent, root); 106 } else { 107 { 108 register struct rb_node *uncle = gparent->rb_left; 109 if (uncle && rb_is_red(uncle)) 110 { 111 rb_set_black(uncle); 112 rb_set_black(parent); 113 rb_set_red(gparent); 114 node = gparent; 115 continue; 116 } 117 } 118 119 if (parent->rb_left == node) 120 { 121 register struct rb_node *tmp; 122 __rb_rotate_right(parent, root); 123 tmp = parent; 124 parent = node; 125 node = tmp; 126 } 127 128 rb_set_black(parent); 129 rb_set_red(gparent); 130 __rb_rotate_left(gparent, root); 131 } 132 } 133 134 rb_set_black(root->rb_node); 135 } 136 EXPORT_SYMBOL(rb_insert_color); 137 138 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, 139 struct rb_root *root) 140 { 141 struct rb_node *other; 142 143 while ((!node || rb_is_black(node)) && node != root->rb_node) 144 { 145 if (parent->rb_left == node) 146 { 147 other = parent->rb_right; 148 if (rb_is_red(other)) 149 { 150 rb_set_black(other); 151 rb_set_red(parent); 152 __rb_rotate_left(parent, root); 153 other = parent->rb_right; 154 } 155 if ((!other->rb_left || rb_is_black(other->rb_left)) && 156 (!other->rb_right || rb_is_black(other->rb_right))) 157 { 158 rb_set_red(other); 159 node = parent; 160 parent = rb_parent(node); 161 } 162 else 163 { 164 if (!other->rb_right || rb_is_black(other->rb_right)) 165 { 166 rb_set_black(other->rb_left); 167 rb_set_red(other); 168 __rb_rotate_right(other, root); 169 other = parent->rb_right; 170 } 171 rb_set_color(other, rb_color(parent)); 172 rb_set_black(parent); 173 rb_set_black(other->rb_right); 174 __rb_rotate_left(parent, root); 175 node = root->rb_node; 176 break; 177 } 178 } 179 else 180 { 181 other = parent->rb_left; 182 if (rb_is_red(other)) 183 { 184 rb_set_black(other); 185 rb_set_red(parent); 186 __rb_rotate_right(parent, root); 187 other = parent->rb_left; 188 } 189 if ((!other->rb_left || rb_is_black(other->rb_left)) && 190 (!other->rb_right || rb_is_black(other->rb_right))) 191 { 192 rb_set_red(other); 193 node = parent; 194 parent = rb_parent(node); 195 } 196 else 197 { 198 if (!other->rb_left || rb_is_black(other->rb_left)) 199 { 200 rb_set_black(other->rb_right); 201 rb_set_red(other); 202 __rb_rotate_left(other, root); 203 other = parent->rb_left; 204 } 205 rb_set_color(other, rb_color(parent)); 206 rb_set_black(parent); 207 rb_set_black(other->rb_left); 208 __rb_rotate_right(parent, root); 209 node = root->rb_node; 210 break; 211 } 212 } 213 } 214 if (node) 215 rb_set_black(node); 216 } 217 218 void rb_erase(struct rb_node *node, struct rb_root *root) 219 { 220 struct rb_node *child, *parent; 221 int color; 222 223 if (!node->rb_left) 224 child = node->rb_right; 225 else if (!node->rb_right) 226 child = node->rb_left; 227 else 228 { 229 struct rb_node *old = node, *left; 230 231 node = node->rb_right; 232 while ((left = node->rb_left) != NULL) 233 node = left; 234 235 if (rb_parent(old)) { 236 if (rb_parent(old)->rb_left == old) 237 rb_parent(old)->rb_left = node; 238 else 239 rb_parent(old)->rb_right = node; 240 } else 241 root->rb_node = node; 242 243 child = node->rb_right; 244 parent = rb_parent(node); 245 color = rb_color(node); 246 247 if (parent == old) { 248 parent = node; 249 } else { 250 if (child) 251 rb_set_parent(child, parent); 252 parent->rb_left = child; 253 254 node->rb_right = old->rb_right; 255 rb_set_parent(old->rb_right, node); 256 } 257 258 node->rb_parent_color = old->rb_parent_color; 259 node->rb_left = old->rb_left; 260 rb_set_parent(old->rb_left, node); 261 262 goto color; 263 } 264 265 parent = rb_parent(node); 266 color = rb_color(node); 267 268 if (child) 269 rb_set_parent(child, parent); 270 if (parent) 271 { 272 if (parent->rb_left == node) 273 parent->rb_left = child; 274 else 275 parent->rb_right = child; 276 } 277 else 278 root->rb_node = child; 279 280 color: 281 if (color == RB_BLACK) 282 __rb_erase_color(child, parent, root); 283 } 284 EXPORT_SYMBOL(rb_erase); 285 286 static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data) 287 { 288 struct rb_node *parent; 289 290 up: 291 func(node, data); 292 parent = rb_parent(node); 293 if (!parent) 294 return; 295 296 if (node == parent->rb_left && parent->rb_right) 297 func(parent->rb_right, data); 298 else if (parent->rb_left) 299 func(parent->rb_left, data); 300 301 node = parent; 302 goto up; 303 } 304 305 /* 306 * after inserting @node into the tree, update the tree to account for 307 * both the new entry and any damage done by rebalance 308 */ 309 void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data) 310 { 311 if (node->rb_left) 312 node = node->rb_left; 313 else if (node->rb_right) 314 node = node->rb_right; 315 316 rb_augment_path(node, func, data); 317 } 318 319 /* 320 * before removing the node, find the deepest node on the rebalance path 321 * that will still be there after @node gets removed 322 */ 323 struct rb_node *rb_augment_erase_begin(struct rb_node *node) 324 { 325 struct rb_node *deepest; 326 327 if (!node->rb_right && !node->rb_left) 328 deepest = rb_parent(node); 329 else if (!node->rb_right) 330 deepest = node->rb_left; 331 else if (!node->rb_left) 332 deepest = node->rb_right; 333 else { 334 deepest = rb_next(node); 335 if (deepest->rb_right) 336 deepest = deepest->rb_right; 337 else if (rb_parent(deepest) != node) 338 deepest = rb_parent(deepest); 339 } 340 341 return deepest; 342 } 343 344 /* 345 * after removal, update the tree to account for the removed entry 346 * and any rebalance damage. 347 */ 348 void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data) 349 { 350 if (node) 351 rb_augment_path(node, func, data); 352 } 353 354 /* 355 * This function returns the first node (in sort order) of the tree. 356 */ 357 struct rb_node *rb_first(const struct rb_root *root) 358 { 359 struct rb_node *n; 360 361 n = root->rb_node; 362 if (!n) 363 return NULL; 364 while (n->rb_left) 365 n = n->rb_left; 366 return n; 367 } 368 EXPORT_SYMBOL(rb_first); 369 370 struct rb_node *rb_last(const struct rb_root *root) 371 { 372 struct rb_node *n; 373 374 n = root->rb_node; 375 if (!n) 376 return NULL; 377 while (n->rb_right) 378 n = n->rb_right; 379 return n; 380 } 381 EXPORT_SYMBOL(rb_last); 382 383 struct rb_node *rb_next(const struct rb_node *node) 384 { 385 struct rb_node *parent; 386 387 if (rb_parent(node) == node) 388 return NULL; 389 390 /* If we have a right-hand child, go down and then left as far 391 as we can. */ 392 if (node->rb_right) { 393 node = node->rb_right; 394 while (node->rb_left) 395 node=node->rb_left; 396 return (struct rb_node *)node; 397 } 398 399 /* No right-hand children. Everything down and left is 400 smaller than us, so any 'next' node must be in the general 401 direction of our parent. Go up the tree; any time the 402 ancestor is a right-hand child of its parent, keep going 403 up. First time it's a left-hand child of its parent, said 404 parent is our 'next' node. */ 405 while ((parent = rb_parent(node)) && node == parent->rb_right) 406 node = parent; 407 408 return parent; 409 } 410 EXPORT_SYMBOL(rb_next); 411 412 struct rb_node *rb_prev(const struct rb_node *node) 413 { 414 struct rb_node *parent; 415 416 if (rb_parent(node) == node) 417 return NULL; 418 419 /* If we have a left-hand child, go down and then right as far 420 as we can. */ 421 if (node->rb_left) { 422 node = node->rb_left; 423 while (node->rb_right) 424 node=node->rb_right; 425 return (struct rb_node *)node; 426 } 427 428 /* No left-hand children. Go up till we find an ancestor which 429 is a right-hand child of its parent */ 430 while ((parent = rb_parent(node)) && node == parent->rb_left) 431 node = parent; 432 433 return parent; 434 } 435 EXPORT_SYMBOL(rb_prev); 436 437 void rb_replace_node(struct rb_node *victim, struct rb_node *new, 438 struct rb_root *root) 439 { 440 struct rb_node *parent = rb_parent(victim); 441 442 /* Set the surrounding nodes to point to the replacement */ 443 if (parent) { 444 if (victim == parent->rb_left) 445 parent->rb_left = new; 446 else 447 parent->rb_right = new; 448 } else { 449 root->rb_node = new; 450 } 451 if (victim->rb_left) 452 rb_set_parent(victim->rb_left, new); 453 if (victim->rb_right) 454 rb_set_parent(victim->rb_right, new); 455 456 /* Copy the pointers/colour from the victim to the replacement */ 457 *new = *victim; 458 } 459 EXPORT_SYMBOL(rb_replace_node); 460
