LXR linux/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-----------------------------------------------------------------------
  34static 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
  54static 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
  80static 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
 100struct 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
 110struct 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
 123static 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}
 127static 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
 139extern void rb_insert_color(struct rb_node *, struct rb_root *);
 140extern void rb_erase(struct rb_node *, struct rb_root *);
 141
 142/* Find logical next and previous nodes in a tree */
 143extern struct rb_node *rb_next(struct rb_node *);
 144extern struct rb_node *rb_prev(struct rb_node *);
 145extern struct rb_node *rb_first(struct rb_root *);
 146extern struct rb_node *rb_last(struct rb_root *);
 147
 148/* Fast replacement of a single node without remove/rebalance/add/rebalance */
 149extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 
 150                            struct rb_root *root);
 151
 152static 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 */
 162