1 /* 2 Red Black Trees 3 (C) 1999 Andrea Arcangeli <andrea@suse.de> 4 (C) 2002 David Woodhouse <dwmw2@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 <ubi_uboot.h> 24 #include <linux/rbtree.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 } 136 137 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, 138 struct rb_root *root) 139 { 140 struct rb_node *other; 141 142 while ((!node || rb_is_black(node)) && node != root->rb_node) 143 { 144 if (parent->rb_left == node) 145 { 146 other = parent->rb_right; 147 if (rb_is_red(other)) 148 { 149 rb_set_black(other); 150 rb_set_red(parent); 151 __rb_rotate_left(parent, root); 152 other = parent->rb_right; 153 } 154 if ((!other->rb_left || rb_is_black(other->rb_left)) && 155 (!other->rb_right || rb_is_black(other->rb_right))) 156 { 157 rb_set_red(other); 158 node = parent; 159 parent = rb_parent(node); 160 } 161 else 162 { 163 if (!other->rb_right || rb_is_black(other->rb_right)) 164 { 165 struct rb_node *o_left; 166 if ((o_left = other->rb_left)) 167 rb_set_black(o_left); 168 rb_set_red(other); 169 __rb_rotate_right(other, root); 170 other = parent->rb_right; 171 } 172 rb_set_color(other, rb_color(parent)); 173 rb_set_black(parent); 174 if (other->rb_right) 175 rb_set_black(other->rb_right); 176 __rb_rotate_left(parent, root); 177 node = root->rb_node; 178 break; 179 } 180 } 181 else 182 { 183 other = parent->rb_left; 184 if (rb_is_red(other)) 185 { 186 rb_set_black(other); 187 rb_set_red(parent); 188 __rb_rotate_right(parent, root); 189 other = parent->rb_left; 190 } 191 if ((!other->rb_left || rb_is_black(other->rb_left)) && 192 (!other->rb_right || rb_is_black(other->rb_right))) 193 { 194 rb_set_red(other); 195 node = parent; 196 parent = rb_parent(node); 197 } 198 else 199 { 200 if (!other->rb_left || rb_is_black(other->rb_left)) 201 { 202 register struct rb_node *o_right; 203 if ((o_right = other->rb_right)) 204 rb_set_black(o_right); 205 rb_set_red(other); 206 __rb_rotate_left(other, root); 207 other = parent->rb_left; 208 } 209 rb_set_color(other, rb_color(parent)); 210 rb_set_black(parent); 211 if (other->rb_left) 212 rb_set_black(other->rb_left); 213 __rb_rotate_right(parent, root); 214 node = root->rb_node; 215 break; 216 } 217 } 218 } 219 if (node) 220 rb_set_black(node); 221 } 222 223 void rb_erase(struct rb_node *node, struct rb_root *root) 224 { 225 struct rb_node *child, *parent; 226 int color; 227 228 if (!node->rb_left) 229 child = node->rb_right; 230 else if (!node->rb_right) 231 child = node->rb_left; 232 else 233 { 234 struct rb_node *old = node, *left; 235 236 node = node->rb_right; 237 while ((left = node->rb_left) != NULL) 238 node = left; 239 child = node->rb_right; 240 parent = rb_parent(node); 241 color = rb_color(node); 242 243 if (child) 244 rb_set_parent(child, parent); 245 if (parent == old) { 246 parent->rb_right = child; 247 parent = node; 248 } else 249 parent->rb_left = child; 250 251 node->rb_parent_color = old->rb_parent_color; 252 node->rb_right = old->rb_right; 253 node->rb_left = old->rb_left; 254 255 if (rb_parent(old)) 256 { 257 if (rb_parent(old)->rb_left == old) 258 rb_parent(old)->rb_left = node; 259 else 260 rb_parent(old)->rb_right = node; 261 } else 262 root->rb_node = node; 263 264 rb_set_parent(old->rb_left, node); 265 if (old->rb_right) 266 rb_set_parent(old->rb_right, node); 267 goto color; 268 } 269 270 parent = rb_parent(node); 271 color = rb_color(node); 272 273 if (child) 274 rb_set_parent(child, parent); 275 if (parent) 276 { 277 if (parent->rb_left == node) 278 parent->rb_left = child; 279 else 280 parent->rb_right = child; 281 } 282 else 283 root->rb_node = child; 284 285 color: 286 if (color == RB_BLACK) 287 __rb_erase_color(child, parent, root); 288 } 289 290 /* 291 * This function returns the first node (in sort order) of the tree. 292 */ 293 struct rb_node *rb_first(struct rb_root *root) 294 { 295 struct rb_node *n; 296 297 n = root->rb_node; 298 if (!n) 299 return NULL; 300 while (n->rb_left) 301 n = n->rb_left; 302 return n; 303 } 304 305 struct rb_node *rb_last(struct rb_root *root) 306 { 307 struct rb_node *n; 308 309 n = root->rb_node; 310 if (!n) 311 return NULL; 312 while (n->rb_right) 313 n = n->rb_right; 314 return n; 315 } 316 317 struct rb_node *rb_next(struct rb_node *node) 318 { 319 struct rb_node *parent; 320 321 if (rb_parent(node) == node) 322 return NULL; 323 324 /* If we have a right-hand child, go down and then left as far 325 as we can. */ 326 if (node->rb_right) { 327 node = node->rb_right; 328 while (node->rb_left) 329 node=node->rb_left; 330 return node; 331 } 332 333 /* No right-hand children. Everything down and left is 334 smaller than us, so any 'next' node must be in the general 335 direction of our parent. Go up the tree; any time the 336 ancestor is a right-hand child of its parent, keep going 337 up. First time it's a left-hand child of its parent, said 338 parent is our 'next' node. */ 339 while ((parent = rb_parent(node)) && node == parent->rb_right) 340 node = parent; 341 342 return parent; 343 } 344 345 struct rb_node *rb_prev(struct rb_node *node) 346 { 347 struct rb_node *parent; 348 349 if (rb_parent(node) == node) 350 return NULL; 351 352 /* If we have a left-hand child, go down and then right as far 353 as we can. */ 354 if (node->rb_left) { 355 node = node->rb_left; 356 while (node->rb_right) 357 node=node->rb_right; 358 return node; 359 } 360 361 /* No left-hand children. Go up till we find an ancestor which 362 is a right-hand child of its parent */ 363 while ((parent = rb_parent(node)) && node == parent->rb_left) 364 node = parent; 365 366 return parent; 367 } 368 369 void rb_replace_node(struct rb_node *victim, struct rb_node *new, 370 struct rb_root *root) 371 { 372 struct rb_node *parent = rb_parent(victim); 373 374 /* Set the surrounding nodes to point to the replacement */ 375 if (parent) { 376 if (victim == parent->rb_left) 377 parent->rb_left = new; 378 else 379 parent->rb_right = new; 380 } else { 381 root->rb_node = new; 382 } 383 if (victim->rb_left) 384 rb_set_parent(victim->rb_left, new); 385 if (victim->rb_right) 386 rb_set_parent(victim->rb_right, new); 387 388 /* Copy the pointers/colour from the victim to the replacement */ 389 *new = *victim; 390 } 391