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   1 /*
   2   Red Black Trees
   3   (C) 1999  Andrea Arcangeli <andrea@suse.de>
   4   (C) 2002  David Woodhouse <dwmw2@infradead.org>
   5   (C) 2012  Michel Lespinasse <walken@google.com>
   6
   7   This program is free software; you can redistribute it and/or modify
   8   it under the terms of the GNU General Public License as published by
   9   the Free Software Foundation; either version 2 of the License, or
  10   (at your option) any later version.
  11
  12   This program is distributed in the hope that it will be useful,
  13   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15   GNU General Public License for more details.
  16
  17   You should have received a copy of the GNU General Public License
  18   along with this program; if not, write to the Free Software
  19   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20
  21   linux/include/linux/rbtree_augmented.h
  22 */
  23
  24 #ifndef _LINUX_RBTREE_AUGMENTED_H
  25 #define _LINUX_RBTREE_AUGMENTED_H
  26
  27 #include "rbtree.h"
  28 #include "util.h"
  29
  30 /*
  31  * Please note - only struct rb_augment_callbacks and the prototypes for
  32  * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
  33  * The rest are implementation details you are not expected to depend on.
  34  *
  35  * See Documentation/rbtree.txt for documentation and samples.
  36  */
  37
  38 struct rb_augment_callbacks {
  39         void (*propagate)(struct rb_node *node, struct rb_node *stop);
  40         void (*copy)(struct rb_node *old, struct rb_node *new);
  41         void (*rotate)(struct rb_node *old, struct rb_node *new);
  42 };
  43
  44 extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
  45         void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
  46 static inline void
  47 rb_insert_augmented(struct rb_node *node, struct rb_root *root,
  48                     const struct rb_augment_callbacks *augment)
  49 {
  50         __rb_insert_augmented(node, root, augment->rotate);
  51 }
  52
  53 #define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,       \
  54                              rbtype, rbaugmented, rbcompute)            \
  55 static inline void                                                      \
  56 rbname ## _propagate(struct rb_node *rb, struct rb_node *stop)          \
  57 {                                                                       \
  58         while (rb != stop) {                                            \
  59                 rbstruct *node = rb_entry(rb, rbstruct, rbfield);       \
  60                 rbtype augmented = rbcompute(node);                     \
  61                 if (node->rbaugmented == augmented)                     \
  62                         break;                                          \
  63                 node->rbaugmented = augmented;                          \
  64                 rb = rb_parent(&node->rbfield);                         \
  65         }                                                               \
  66 }                                                                       \
  67 static inline void                                                      \
  68 rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)         \
  69 {                                                                       \
  70         rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
  71         rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
  72         new->rbaugmented = old->rbaugmented;                            \
  73 }                                                                       \
  74 static void                                                             \
  75 rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)       \
  76 {                                                                       \
  77         rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
  78         rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
  79         new->rbaugmented = old->rbaugmented;                            \
  80         old->rbaugmented = rbcompute(old);                              \
  81 }                                                                       \
  82 rbstatic const struct rb_augment_callbacks rbname = {                   \
  83         rbname ## _propagate, rbname ## _copy, rbname ## _rotate        \
  84 };
  85
  86
  87 #define RB_RED          0
  88 #define RB_BLACK        1
  89
  90 #define __rb_parent(pc)    ((struct rb_node *)(pc & ~3))
  91
  92 #define __rb_color(pc)     ((pc) & 1)
  93 #define __rb_is_black(pc)  __rb_color(pc)
  94 #define __rb_is_red(pc)    (!__rb_color(pc))
  95 #define rb_color(rb)       __rb_color((rb)->__rb_parent_color)
  96 #define rb_is_red(rb)      __rb_is_red((rb)->__rb_parent_color)
  97 #define rb_is_black(rb)    __rb_is_black((rb)->__rb_parent_color)
  98
  99 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
 100 {
 101         rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
 102 }
 103
 104 static inline void rb_set_parent_color(struct rb_node *rb,
 105                                        struct rb_node *p, int color)
 106 {
 107         rb->__rb_parent_color = (unsigned long)p | color;
 108 }
 109
 110 static inline void
 111 __rb_change_child(struct rb_node *old, struct rb_node *new,
 112                   struct rb_node *parent, struct rb_root *root)
 113 {
 114         if (parent) {
 115                 if (parent->rb_left == old)
 116                         parent->rb_left = new;
 117                 else
 118                         parent->rb_right = new;
 119         } else
 120                 root->rb_node = new;
 121 }
 122
 123 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
 124         void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
 125
 126 static ALWAYS_INLINE void
 127 rb_erase_augmented(struct rb_node *node, struct rb_root *root,
 128                    const struct rb_augment_callbacks *augment)
 129 {
 130         struct rb_node *child = node->rb_right, *tmp = node->rb_left;
 131         struct rb_node *parent, *rebalance;
 132         unsigned long pc;
 133
 134         if (!tmp) {
 135                 /*
 136                  * Case 1: node to erase has no more than 1 child (easy!)
 137                  *
 138                  * Note that if there is one child it must be red due to 5)
 139                  * and node must be black due to 4). We adjust colors locally
 140                  * so as to bypass __rb_erase_color() later on.
 141                  */
 142                 pc = node->__rb_parent_color;
 143                 parent = __rb_parent(pc);
 144                 __rb_change_child(node, child, parent, root);
 145                 if (child) {
 146                         child->__rb_parent_color = pc;
 147                         rebalance = NULL;
 148                 } else
 149                         rebalance = __rb_is_black(pc) ? parent : NULL;
 150                 tmp = parent;
 151         } else if (!child) {
 152                 /* Still case 1, but this time the child is node->rb_left */
 153                 tmp->__rb_parent_color = pc = node->__rb_parent_color;
 154                 parent = __rb_parent(pc);
 155                 __rb_change_child(node, tmp, parent, root);
 156                 rebalance = NULL;
 157                 tmp = parent;
 158         } else {
 159                 struct rb_node *successor = child, *child2;
 160                 tmp = child->rb_left;
 161                 if (!tmp) {
 162                         /*
 163                          * Case 2: node's successor is its right child
 164                          *
 165                          *    (n)          (s)
 166                          *    / \          / \
 167                          *  (x) (s)  ->  (x) (c)
 168                          *        \
 169                          *        (c)
 170                          */
 171                         parent = successor;
 172                         child2 = successor->rb_right;
 173                         augment->copy(node, successor);
 174                 } else {
 175                         /*
 176                          * Case 3: node's successor is leftmost under
 177                          * node's right child subtree
 178                          *
 179                          *    (n)          (s)
 180                          *    / \          / \
 181                          *  (x) (y)  ->  (x) (y)
 182                          *      /            /
 183                          *    (p)          (p)
 184                          *    /            /
 185                          *  (s)          (c)
 186                          *    \
 187                          *    (c)
 188                          */
 189                         do {
 190                                 parent = successor;
 191                                 successor = tmp;
 192                                 tmp = tmp->rb_left;
 193                         } while (tmp);
 194                         parent->rb_left = child2 = successor->rb_right;
 195                         successor->rb_right = child;
 196                         rb_set_parent(child, successor);
 197                         augment->copy(node, successor);
 198                         augment->propagate(parent, successor);
 199                 }
 200
 201                 successor->rb_left = tmp = node->rb_left;
 202                 rb_set_parent(tmp, successor);
 203
 204                 pc = node->__rb_parent_color;
 205                 tmp = __rb_parent(pc);
 206                 __rb_change_child(node, successor, tmp, root);
 207                 if (child2) {
 208                         successor->__rb_parent_color = pc;
 209                         rb_set_parent_color(child2, parent, RB_BLACK);
 210                         rebalance = NULL;
 211                 } else {
 212                         unsigned long pc2 = successor->__rb_parent_color;
 213                         successor->__rb_parent_color = pc;
 214                         rebalance = __rb_is_black(pc2) ? parent : NULL;
 215                 }
 216                 tmp = successor;
 217         }
 218
 219         augment->propagate(tmp, NULL);
 220         if (rebalance)
 221                 __rb_erase_color(rebalance, root, augment->rotate);
 222 }
 223
 224 #endif  /* _LINUX_RBTREE_AUGMENTED_H */