palacios/src/palacios/vmm_rbtree.c

   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 <palacios/vmm_rbtree.h>
  24
  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     }
  57
  58     left->rb_right = node;
  59
  60     rb_set_parent(left, parent);
  61
  62     if (parent) {
  63         if (node == parent->rb_right) {
  64             parent->rb_right = left;
  65         } else {
  66             parent->rb_left = left;
  67         }
  68     } else {
  69         root->rb_node = left;
  70     }
  71
  72     rb_set_parent(node, left);
  73 }
  74
  75 void v3_rb_insert_color(struct rb_node *node, struct rb_root *root)
  76 {
  77     struct rb_node *parent, *gparent;
  78
  79     while ((parent = rb_parent(node)) && rb_is_red(parent))
  80         {
  81             gparent = rb_parent(parent);
  82
  83             if (parent == gparent->rb_left)
  84                 {
  85                     {
  86                         register struct rb_node *uncle = gparent->rb_right;
  87                         if (uncle && rb_is_red(uncle))
  88                             {
  89                                 rb_set_black(uncle);
  90                                 rb_set_black(parent);
  91                                 rb_set_red(gparent);
  92                                 node = gparent;
  93                                 continue;
  94                             }
  95                     }
  96
  97                     if (parent->rb_right == node)
  98                         {
  99                             register struct rb_node *tmp;
 100                             __rb_rotate_left(parent, root);
 101                             tmp = parent;
 102                             parent = node;
 103                             node = tmp;
 104                         }
 105
 106                     rb_set_black(parent);
 107                     rb_set_red(gparent);
 108                     __rb_rotate_right(gparent, root);
 109                 } else {
 110                 {
 111                     register struct rb_node *uncle = gparent->rb_left;
 112                     if (uncle && rb_is_red(uncle))
 113                         {
 114                             rb_set_black(uncle);
 115                             rb_set_black(parent);
 116                             rb_set_red(gparent);
 117                             node = gparent;
 118                             continue;
 119                         }
 120                 }
 121
 122                 if (parent->rb_left == node)
 123                     {
 124                         register struct rb_node *tmp;
 125                         __rb_rotate_right(parent, root);
 126                         tmp = parent;
 127                         parent = node;
 128                         node = tmp;
 129                     }
 130
 131                 rb_set_black(parent);
 132                 rb_set_red(gparent);
 133                 __rb_rotate_left(gparent, root);
 134             }
 135         }
 136
 137     rb_set_black(root->rb_node);
 138 }
 139
 140
 141 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
 142                              struct rb_root *root)
 143 {
 144     struct rb_node *other;
 145
 146     while ((!node || rb_is_black(node)) && node != root->rb_node)
 147         {
 148             if (parent->rb_left == node)
 149                 {
 150                     other = parent->rb_right;
 151                     if (rb_is_red(other))
 152                         {
 153                             rb_set_black(other);
 154                             rb_set_red(parent);
 155                             __rb_rotate_left(parent, root);
 156                             other = parent->rb_right;
 157                         }
 158                     if ((!other->rb_left || rb_is_black(other->rb_left)) &&
 159                         (!other->rb_right || rb_is_black(other->rb_right)))
 160                         {
 161                             rb_set_red(other);
 162                             node = parent;
 163                             parent = rb_parent(node);
 164                         }
 165                     else
 166                         {
 167                             if (!other->rb_right || rb_is_black(other->rb_right))
 168                                 {
 169                                     struct rb_node *o_left;
 170                                     if ((o_left = other->rb_left))
 171                                         rb_set_black(o_left);
 172                                     rb_set_red(other);
 173                                     __rb_rotate_right(other, root);
 174                                     other = parent->rb_right;
 175                                 }
 176                             rb_set_color(other, rb_color(parent));
 177                             rb_set_black(parent);
 178                             if (other->rb_right)
 179                                 rb_set_black(other->rb_right);
 180                             __rb_rotate_left(parent, root);
 181                             node = root->rb_node;
 182                             break;
 183                         }
 184                 }
 185             else
 186                 {
 187                     other = parent->rb_left;
 188                     if (rb_is_red(other))
 189                         {
 190                             rb_set_black(other);
 191                             rb_set_red(parent);
 192                             __rb_rotate_right(parent, root);
 193                             other = parent->rb_left;
 194                         }
 195                     if ((!other->rb_left || rb_is_black(other->rb_left)) &&
 196                         (!other->rb_right || rb_is_black(other->rb_right)))
 197                         {
 198                             rb_set_red(other);
 199                             node = parent;
 200                             parent = rb_parent(node);
 201                         }
 202                     else
 203                         {
 204                             if (!other->rb_left || rb_is_black(other->rb_left))
 205                                 {
 206                                     register struct rb_node *o_right;
 207                                     if ((o_right = other->rb_right))
 208                                         rb_set_black(o_right);
 209                                     rb_set_red(other);
 210                                     __rb_rotate_left(other, root);
 211                                     other = parent->rb_left;
 212                                 }
 213                             rb_set_color(other, rb_color(parent));
 214                             rb_set_black(parent);
 215                             if (other->rb_left)
 216                                 rb_set_black(other->rb_left);
 217                             __rb_rotate_right(parent, root);
 218                             node = root->rb_node;
 219                             break;
 220                         }
 221                 }
 222         }
 223     if (node)
 224         rb_set_black(node);
 225 }
 226
 227 void v3_rb_erase(struct rb_node *node, struct rb_root *root)
 228 {
 229     struct rb_node *child, *parent;
 230     int color;
 231
 232     if (!node->rb_left)
 233         child = node->rb_right;
 234     else if (!node->rb_right)
 235         child = node->rb_left;
 236     else
 237         {
 238             struct rb_node *old = node, *left;
 239
 240             node = node->rb_right;
 241             while ((left = node->rb_left) != NULL)
 242                 node = left;
 243             child = node->rb_right;
 244             parent = rb_parent(node);
 245             color = rb_color(node);
 246
 247             if (child)
 248                 rb_set_parent(child, parent);
 249             if (parent == old) {
 250                 parent->rb_right = child;
 251                 parent = node;
 252             } else
 253                 parent->rb_left = child;
 254
 255             node->rb_parent_color = old->rb_parent_color;
 256             node->rb_right = old->rb_right;
 257             node->rb_left = old->rb_left;
 258
 259             if (rb_parent(old))
 260                 {
 261                     if (rb_parent(old)->rb_left == old)
 262                         rb_parent(old)->rb_left = node;
 263                     else
 264                         rb_parent(old)->rb_right = node;
 265                 } else
 266                 root->rb_node = node;
 267
 268             rb_set_parent(old->rb_left, node);
 269             if (old->rb_right)
 270                 rb_set_parent(old->rb_right, node);
 271             goto color;
 272         }
 273
 274     parent = rb_parent(node);
 275     color = rb_color(node);
 276
 277     if (child)
 278         rb_set_parent(child, parent);
 279     if (parent)
 280         {
 281             if (parent->rb_left == node)
 282                 parent->rb_left = child;
 283             else
 284                 parent->rb_right = child;
 285         }
 286     else
 287         root->rb_node = child;
 288
 289  color:
 290     // parent check here is because a possible
 291     // codepath here has parent=null, which would
 292     // be a disaster in kernel
 293     if (color == RB_BLACK && parent)
 294         __rb_erase_color(child, parent, root);
 295 }
 296
 297
 298 /*
 299  * This function returns the first node (in sort order) of the tree.
 300  */
 301 struct rb_node *v3_rb_first(struct rb_root *root)
 302 {
 303     struct rb_node      *n;
 304
 305     n = root->rb_node;
 306     if (!n)
 307         return NULL;
 308     while (n->rb_left)
 309         n = n->rb_left;
 310     return n;
 311 }
 312
 313
 314 struct rb_node *v3_rb_last(struct rb_root *root)
 315 {
 316     struct rb_node      *n;
 317
 318     n = root->rb_node;
 319     if (!n)
 320         return NULL;
 321     while (n->rb_right)
 322         n = n->rb_right;
 323     return n;
 324 }
 325
 326
 327 struct rb_node *v3_rb_next(struct rb_node *node)
 328 {
 329     struct rb_node *parent;
 330
 331     /* If we have a right-hand child, go down and then left as far
 332        as we can. */
 333     if (node->rb_right) {
 334         node = node->rb_right;
 335         while (node->rb_left)
 336             node=node->rb_left;
 337         return node;
 338     }
 339
 340     /* No right-hand children.  Everything down and left is
 341        smaller than us, so any 'next' node must be in the general
 342        direction of our parent. Go up the tree; any time the
 343        ancestor is a right-hand child of its parent, keep going
 344        up. First time it's a left-hand child of its parent, said
 345        parent is our 'next' node. */
 346     while ((parent = rb_parent(node)) && node == parent->rb_right)
 347         node = parent;
 348
 349     return parent;
 350 }
 351
 352
 353 struct rb_node *v3_rb_prev(struct rb_node *node)
 354 {
 355     struct rb_node *parent;
 356
 357     /* If we have a left-hand child, go down and then right as far
 358        as we can. */
 359     if (node->rb_left) {
 360         node = node->rb_left;
 361         while (node->rb_right)
 362             node=node->rb_right;
 363         return node;
 364     }
 365
 366     /* No left-hand children. Go up till we find an ancestor which
 367        is a right-hand child of its parent */
 368     while ((parent = rb_parent(node)) && node == parent->rb_left)
 369         node = parent;
 370
 371     return parent;
 372 }
 373
 374
 375 void v3_rb_replace_node(struct rb_node *victim, struct rb_node *new,
 376                         struct rb_root *root)
 377 {
 378     struct rb_node *parent = rb_parent(victim);
 379
 380     /* Set the surrounding nodes to point to the replacement */
 381     if (parent) {
 382         if (victim == parent->rb_left)
 383             parent->rb_left = new;
 384         else
 385             parent->rb_right = new;
 386     } else {
 387         root->rb_node = new;
 388     }
 389     if (victim->rb_left)
 390         rb_set_parent(victim->rb_left, new);
 391     if (victim->rb_right)
 392         rb_set_parent(victim->rb_right, new);
 393
 394     /* Copy the pointers/colour from the victim to the replacement */
 395     *new = *victim;
 396 }
 397