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/*

  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 */