root/include/linux/rbtree.h

INCLUDED FROM

DEFINITIONS

1. rb_set_parent
2. rb_set_color
3. rb_link_node

/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  linux/include/linux/rbtree.h

  To use rbtrees you'll have to implement your own insert and search cores.
  This will avoid us to use callbacks and to drop drammatically performances.
  I know it's not the cleaner way,  but in C (not in C++) to get
  performances and genericity...

  Some example of insert and search follows here. The search is a plain
  normal search over an ordered tree. The insert instead must be implemented
  int two steps: as first thing the code must insert the element in
  order as a red leaf in the tree, then the support library function
  rb_insert_color() must be called. Such function will do the
  not trivial work to rebalance the rbtree if necessary.

-----------------------------------------------------------------------
static inline struct page * rb_search_page_cache(struct inode * inode,
                                                 unsigned long offset)
{
        struct rb_node * n = inode->i_rb_page_cache.rb_node;
        struct page * page;

        while (n)
        {
                page = rb_entry(n, struct page, rb_page_cache);

                if (offset < page->offset)
                        n = n->rb_left;
                else if (offset > page->offset)
                        n = n->rb_right;
                else
                        return page;
        }
        return NULL;
}

static inline struct page * __rb_insert_page_cache(struct inode * inode,
                                                   unsigned long offset,
                                                   struct rb_node * node)
{
        struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
        struct rb_node * parent = NULL;
        struct page * page;

        while (*p)
        {
                parent = *p;
                page = rb_entry(parent, struct page, rb_page_cache);

                if (offset < page->offset)
                        p = &(*p)->rb_left;
                else if (offset > page->offset)
                        p = &(*p)->rb_right;
                else
                        return page;
        }

        rb_link_node(node, parent, p);

        return NULL;
}

static inline struct page * rb_insert_page_cache(struct inode * inode,
                                                 unsigned long offset,
                                                 struct rb_node * node)
{
        struct page * ret;
        if ((ret = __rb_insert_page_cache(inode, offset, node)))
                goto out;
        rb_insert_color(node, &inode->i_rb_page_cache);
 out:
        return ret;
}
-----------------------------------------------------------------------
*/

#ifndef _LINUX_RBTREE_H
#define _LINUX_RBTREE_H

#include <linux/kernel.h>
#include <linux/stddef.h>

struct rb_node
{
        unsigned long  rb_parent_color;
#define RB_RED          0
#define RB_BLACK        1
        struct rb_node *rb_right;
        struct rb_node *rb_left;
} __attribute__((aligned(sizeof(long))));
    /* The alignment might seem pointless, but allegedly CRIS needs it */

struct rb_root
{
        struct rb_node *rb_node;
};


#define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
#define rb_color(r)   ((r)->rb_parent_color & 1)
#define rb_is_red(r)   (!rb_color(r))
#define rb_is_black(r) rb_color(r)
#define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
#define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)

static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
{
        rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
}
static inline void rb_set_color(struct rb_node *rb, int color)
{
        rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
}

#define RB_ROOT (struct rb_root) { NULL, }
#define rb_entry(ptr, type, member) container_of(ptr, type, member)

#define RB_EMPTY_ROOT(root)     ((root)->rb_node == NULL)
#define RB_EMPTY_NODE(node)     (rb_parent(node) == node)
#define RB_CLEAR_NODE(node)     (rb_set_parent(node, node))

extern void rb_insert_color(struct rb_node *, struct rb_root *);
extern void rb_erase(struct rb_node *, struct rb_root *);

/* Find logical next and previous nodes in a tree */
extern struct rb_node *rb_next(struct rb_node *);
extern struct rb_node *rb_prev(struct rb_node *);
extern struct rb_node *rb_first(struct rb_root *);
extern struct rb_node *rb_last(struct rb_root *);

/* Fast replacement of a single node without remove/rebalance/add/rebalance */
extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 
                            struct rb_root *root);

static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
                                struct rb_node ** rb_link)
{
        node->rb_parent_color = (unsigned long )parent;
        node->rb_left = node->rb_right = NULL;

        *rb_link = node;
}

#endif  /* _LINUX_RBTREE_H */