LXR linux-old/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        rb_node_t * 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                                                   rb_node_t * node)
  57{
  58        rb_node_t ** p = &inode->i_rb_page_cache.rb_node;
  59        rb_node_t * 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                                                 rb_node_t * 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
 100typedef struct rb_node_s
 101{
 102        struct rb_node_s * rb_parent;
 103        int rb_color;
 104#define RB_RED          0
 105#define RB_BLACK        1
 106        struct rb_node_s * rb_right;
 107        struct rb_node_s * rb_left;
 108}
 109rb_node_t;
 110
 111typedef struct rb_root_s
 112{
 113        struct rb_node_s * rb_node;
 114}
 115rb_root_t;
 116
 117#define RB_ROOT (rb_root_t) { NULL, }
 118#define rb_entry(ptr, type, member)                                     \
 119        ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
 120
 121extern void rb_insert_color(rb_node_t *, rb_root_t *);
 122extern void rb_erase(rb_node_t *, rb_root_t *);
 123
 124/* Find logical next and previous nodes in a tree */
 125extern rb_node_t *rb_next(rb_node_t *);
 126extern rb_node_t *rb_prev(rb_node_t *);
 127extern rb_node_t *rb_first(rb_root_t *);
 128extern rb_node_t *rb_last(rb_root_t *);
 129
 130static inline void rb_link_node(rb_node_t * node, rb_node_t * parent, rb_node_t ** rb_link)
 131{
 132        node->rb_parent = parent;
 133        node->rb_color = RB_RED;
 134        node->rb_left = node->rb_right = NULL;
 135
 136        *rb_link = node;
 137}
 138
 139#endif  /* _LINUX_RBTREE_H */
 140