/*

  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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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 fio_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 fio_rb_node * node)

{

	struct fio_rb_node ** p = &inode->i_rb_page_cache.rb_node;

	struct fio_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 fio_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 <stdlib.h>

#include <inttypes.h>

struct fio_rb_node

{

	intptr_t rb_parent_color;

#define	RB_RED		0

#define	RB_BLACK	1

	struct fio_rb_node *rb_right;

	struct fio_rb_node *rb_left;

} __attribute__((aligned(sizeof(long))));

    /* The alignment might seem pointless, but allegedly CRIS needs it */

struct rb_root

{

	struct fio_rb_node *rb_node;

};

#define rb_parent(r)   ((struct fio_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 fio_rb_node *rb, struct fio_rb_node *p)

{

	rb->rb_parent_color = (rb->rb_parent_color & 3) | (uintptr_t)p;

}

static inline void rb_set_color(struct fio_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 fio_rb_node *, struct rb_root *);

extern void rb_erase(struct fio_rb_node *, struct rb_root *);

/* Find logical next and previous nodes in a tree */

extern struct fio_rb_node *rb_first(struct rb_root *);

extern struct fio_rb_node *rb_next(const struct fio_rb_node *);

static inline void rb_link_node(struct fio_rb_node * node,

				struct fio_rb_node * parent,

				struct fio_rb_node ** rb_link)

{

	node->rb_parent_color = (uintptr_t)parent;

	node->rb_left = node->rb_right = NULL;

	*rb_link = node;

}

#endif	/* _LINUX_RBTREE_H */