LXR uboot/include/linux/rbtree

   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 * SPDX-License-Identifier:     GPL-2.0+
   8
   9  linux/include/linux/rbtree_augmented.h
  10*/
  11
  12#ifndef _LINUX_RBTREE_AUGMENTED_H
  13#define _LINUX_RBTREE_AUGMENTED_H
  14
  15#include <linux/compiler.h>
  16#include <linux/rbtree.h>
  17
  18/*
  19 * Please note - only struct rb_augment_callbacks and the prototypes for
  20 * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
  21 * The rest are implementation details you are not expected to depend on.
  22 *
  23 * See Documentation/rbtree.txt for documentation and samples.
  24 */
  25
  26struct rb_augment_callbacks {
  27        void (*propagate)(struct rb_node *node, struct rb_node *stop);
  28        void (*copy)(struct rb_node *old, struct rb_node *new);
  29        void (*rotate)(struct rb_node *old, struct rb_node *new);
  30};
  31
  32extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
  33        void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
  34static inline void
  35rb_insert_augmented(struct rb_node *node, struct rb_root *root,
  36                    const struct rb_augment_callbacks *augment)
  37{
  38        __rb_insert_augmented(node, root, augment->rotate);
  39}
  40
  41#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,       \
  42                             rbtype, rbaugmented, rbcompute)            \
  43static inline void                                                      \
  44rbname ## _propagate(struct rb_node *rb, struct rb_node *stop)          \
  45{                                                                       \
  46        while (rb != stop) {                                            \
  47                rbstruct *node = rb_entry(rb, rbstruct, rbfield);       \
  48                rbtype augmented = rbcompute(node);                     \
  49                if (node->rbaugmented == augmented)                     \
  50                        break;                                          \
  51                node->rbaugmented = augmented;                          \
  52                rb = rb_parent(&node->rbfield);                         \
  53        }                                                               \
  54}                                                                       \
  55static inline void                                                      \
  56rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)         \
  57{                                                                       \
  58        rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
  59        rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
  60        new->rbaugmented = old->rbaugmented;                            \
  61}                                                                       \
  62static void                                                             \
  63rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)       \
  64{                                                                       \
  65        rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
  66        rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
  67        new->rbaugmented = old->rbaugmented;                            \
  68        old->rbaugmented = rbcompute(old);                              \
  69}                                                                       \
  70rbstatic const struct rb_augment_callbacks rbname = {                   \
  71        rbname ## _propagate, rbname ## _copy, rbname ## _rotate        \
  72};
  73
  74
  75#define RB_RED          0
  76#define RB_BLACK        1
  77
  78#define __rb_parent(pc)    ((struct rb_node *)(pc & ~3))
  79
  80#define __rb_color(pc)     ((pc) & 1)
  81#define __rb_is_black(pc)  __rb_color(pc)
  82#define __rb_is_red(pc)    (!__rb_color(pc))
  83#define rb_color(rb)       __rb_color((rb)->__rb_parent_color)
  84#define rb_is_red(rb)      __rb_is_red((rb)->__rb_parent_color)
  85#define rb_is_black(rb)    __rb_is_black((rb)->__rb_parent_color)
  86
  87static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
  88{
  89        rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
  90}
  91
  92static inline void rb_set_parent_color(struct rb_node *rb,
  93                                       struct rb_node *p, int color)
  94{
  95        rb->__rb_parent_color = (unsigned long)p | color;
  96}
  97
  98static inline void
  99__rb_change_child(struct rb_node *old, struct rb_node *new,
 100                  struct rb_node *parent, struct rb_root *root)
 101{
 102        if (parent) {
 103                if (parent->rb_left == old)
 104                        parent->rb_left = new;
 105                else
 106                        parent->rb_right = new;
 107        } else
 108                root->rb_node = new;
 109}
 110
 111extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
 112        void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
 113
 114static __always_inline struct rb_node *
 115__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
 116                     const struct rb_augment_callbacks *augment)
 117{
 118        struct rb_node *child = node->rb_right, *tmp = node->rb_left;
 119        struct rb_node *parent, *rebalance;
 120        unsigned long pc;
 121
 122        if (!tmp) {
 123                /*
 124                 * Case 1: node to erase has no more than 1 child (easy!)
 125                 *
 126                 * Note that if there is one child it must be red due to 5)
 127                 * and node must be black due to 4). We adjust colors locally
 128                 * so as to bypass __rb_erase_color() later on.
 129                 */
 130                pc = node->__rb_parent_color;
 131                parent = __rb_parent(pc);
 132                __rb_change_child(node, child, parent, root);
 133                if (child) {
 134                        child->__rb_parent_color = pc;
 135                        rebalance = NULL;
 136                } else
 137                        rebalance = __rb_is_black(pc) ? parent : NULL;
 138                tmp = parent;
 139        } else if (!child) {
 140                /* Still case 1, but this time the child is node->rb_left */
 141                tmp->__rb_parent_color = pc = node->__rb_parent_color;
 142                parent = __rb_parent(pc);
 143                __rb_change_child(node, tmp, parent, root);
 144                rebalance = NULL;
 145                tmp = parent;
 146        } else {
 147                struct rb_node *successor = child, *child2;
 148                tmp = child->rb_left;
 149                if (!tmp) {
 150                        /*
 151                         * Case 2: node's successor is its right child
 152                         *
 153                         *    (n)          (s)
 154                         *    / \          / \
 155                         *  (x) (s)  ->  (x) (c)
 156                         *        \
 157                         *        (c)
 158                         */
 159                        parent = successor;
 160                        child2 = successor->rb_right;
 161                        augment->copy(node, successor);
 162                } else {
 163                        /*
 164                         * Case 3: node's successor is leftmost under
 165                         * node's right child subtree
 166                         *
 167                         *    (n)          (s)
 168                         *    / \          / \
 169                         *  (x) (y)  ->  (x) (y)
 170                         *      /            /
 171                         *    (p)          (p)
 172                         *    /            /
 173                         *  (s)          (c)
 174                         *    \
 175                         *    (c)
 176                         */
 177                        do {
 178                                parent = successor;
 179                                successor = tmp;
 180                                tmp = tmp->rb_left;
 181                        } while (tmp);
 182                        parent->rb_left = child2 = successor->rb_right;
 183                        successor->rb_right = child;
 184                        rb_set_parent(child, successor);
 185                        augment->copy(node, successor);
 186                        augment->propagate(parent, successor);
 187                }
 188
 189                successor->rb_left = tmp = node->rb_left;
 190                rb_set_parent(tmp, successor);
 191
 192                pc = node->__rb_parent_color;
 193                tmp = __rb_parent(pc);
 194                __rb_change_child(node, successor, tmp, root);
 195                if (child2) {
 196                        successor->__rb_parent_color = pc;
 197                        rb_set_parent_color(child2, parent, RB_BLACK);
 198                        rebalance = NULL;
 199                } else {
 200                        unsigned long pc2 = successor->__rb_parent_color;
 201                        successor->__rb_parent_color = pc;
 202                        rebalance = __rb_is_black(pc2) ? parent : NULL;
 203                }
 204                tmp = successor;
 205        }
 206
 207        augment->propagate(tmp, NULL);
 208        return rebalance;
 209}
 210
 211static __always_inline void
 212rb_erase_augmented(struct rb_node *node, struct rb_root *root,
 213                   const struct rb_augment_callbacks *augment)
 214{
 215        struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
 216        if (rebalance)
 217                __rb_erase_color(rebalance, root, augment->rotate);
 218}
 219
 220#endif  /* _LINUX_RBTREE_AUGMENTED_H */
 221