include/linux/rbtree.h

   1 /*
   2   Red Black Trees
   3   (C) 1999  Andrea Arcangeli <andrea@suse.de>
   4
   5   This program is free software; you can redistribute it and/or modify
   6   it under the terms of the GNU General Public License as published by
   7   the Free Software Foundation; either version 2 of the License, or
   8   (at your option) any later version.
   9
  10   This program is distributed in the hope that it will be useful,
  11   but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13   GNU General Public License for more details.
  14
  15   You should have received a copy of the GNU General Public License
  16   along with this program; if not, write to the Free Software
  17   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18
  19   linux/include/linux/rbtree.h
  20
  21   To use rbtrees you'll have to implement your own insert and search cores.
  22   This will avoid us to use callbacks and to drop drammatically performances.
  23   I know it's not the cleaner way,  but in C (not in C++) to get
  24   performances and genericity...
  25
  26   Some example of insert and search follows here. The search is a plain
  27   normal search over an ordered tree. The insert instead must be implemented
  28   int two steps: as first thing the code must insert the element in
  29   order as a red leaf in the tree, then the support library function
  30   rb_insert_color() must be called. Such function will do the
  31   not trivial work to rebalance the rbtree if necessary.
  32
  33 -----------------------------------------------------------------------
  34 static inline struct page * rb_search_page_cache(struct inode * inode,
  35                                                  unsigned long offset)
  36 {
  37         struct rb_node * n = inode->i_rb_page_cache.rb_node;
  38         struct page * page;
  39
  40         while (n)
  41         {
  42                 page = rb_entry(n, struct page, rb_page_cache);
  43
  44                 if (offset < page->offset)
  45                         n = n->rb_left;
  46                 else if (offset > page->offset)
  47                         n = n->rb_right;
  48                 else
  49                         return page;
  50         }
  51         return NULL;
  52 }
  53
  54 static inline struct page * __rb_insert_page_cache(struct inode * inode,
  55                                                    unsigned long offset,
  56                                                    struct rb_node * node)
  57 {
  58         struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
  59         struct rb_node * parent = NULL;
  60         struct page * page;
  61
  62         while (*p)
  63         {
  64                 parent = *p;
  65                 page = rb_entry(parent, struct page, rb_page_cache);
  66
  67                 if (offset < page->offset)
  68                         p = &(*p)->rb_left;
  69                 else if (offset > page->offset)
  70                         p = &(*p)->rb_right;
  71                 else
  72                         return page;
  73         }
  74
  75         rb_link_node(node, parent, p);
  76
  77         return NULL;
  78 }
  79
  80 static inline struct page * rb_insert_page_cache(struct inode * inode,
  81                                                  unsigned long offset,
  82                                                  struct rb_node * node)
  83 {
  84         struct page * ret;
  85         if ((ret = __rb_insert_page_cache(inode, offset, node)))
  86                 goto out;
  87         rb_insert_color(node, &inode->i_rb_page_cache);
  88  out:
  89         return ret;
  90 }
  91 -----------------------------------------------------------------------
  92 */
  93
  94 #ifndef _LINUX_RBTREE_H
  95 #define _LINUX_RBTREE_H
  96
  97 #include <linux/kernel.h>
  98 #include <linux/stddef.h>
  99
 100 struct rb_node
 101 {
 102         unsigned long  rb_parent_color;
 103 #define RB_RED          0
 104 #define RB_BLACK        1
 105         struct rb_node *rb_right;
 106         struct rb_node *rb_left;
 107 } __attribute__((aligned(sizeof(long))));
 108     /* The alignment might seem pointless, but allegedly CRIS needs it */
 109
 110 struct rb_root
 111 {
 112         struct rb_node *rb_node;
 113 };
 114
 115
 116 #define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
 117 #define rb_color(r)   ((r)->rb_parent_color & 1)
 118 #define rb_is_red(r)   (!rb_color(r))
 119 #define rb_is_black(r) rb_color(r)
 120 #define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
 121 #define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)
 122
 123 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
 124 {
 125         rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
 126 }
 127 static inline void rb_set_color(struct rb_node *rb, int color)
 128 {
 129         rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
 130 }
 131
 132 #define RB_ROOT (struct rb_root) { NULL, }
 133 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
 134
 135 #define RB_EMPTY_ROOT(root)     ((root)->rb_node == NULL)
 136 #define RB_EMPTY_NODE(node)     (rb_parent(node) == node)
 137 #define RB_CLEAR_NODE(node)     (rb_set_parent(node, node))
 138
 139 extern void rb_insert_color(struct rb_node *, struct rb_root *);
 140 extern void rb_erase(struct rb_node *, struct rb_root *);
 141
 142 /* Find logical next and previous nodes in a tree */
 143 extern struct rb_node *rb_next(struct rb_node *);
 144 extern struct rb_node *rb_prev(struct rb_node *);
 145 extern struct rb_node *rb_first(struct rb_root *);
 146 extern struct rb_node *rb_last(struct rb_root *);
 147
 148 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
 149 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
 150                             struct rb_root *root);
 151
 152 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
 153                                 struct rb_node ** rb_link)
 154 {
 155         node->rb_parent_color = (unsigned long )parent;
 156         node->rb_left = node->rb_right = NULL;
 157
 158         *rb_link = node;
 159 }
 160
 161 #endif  /* _LINUX_RBTREE_H */