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rbtree.h

/*
  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
{
      struct rb_node *rb_parent;
      int rb_color;
#define     RB_RED            0
#define     RB_BLACK    1
      struct rb_node *rb_right;
      struct rb_node *rb_left;
};

struct rb_root
{
      struct rb_node *rb_node;
};

// Copy from linux kernel 2.6 source (kernel.h, stddef.h)
#define container_of(ptr, type, member) ({      \
      const typeof( ((type *)0)->member ) *__mptr = (ptr);  \
      (type *)( (char *)__mptr - offsetof(type,member) );})
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)


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

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 = parent;
      node->rb_color = RB_RED;
      node->rb_left = node->rb_right = NULL;

      *rb_link = node;
}

#endif      /* _LINUX_RBTREE_H */

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