/* Stolen from Linux 2.6.34 */

/*

  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, see <http://www.gnu.org/licenses/>.

  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 "compiler.h" /* container_of */

#include <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))

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

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

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

struct rb_node *rb_next(const struct rb_node *);

struct rb_node *rb_prev(const struct rb_node *);

struct rb_node *rb_first(const struct rb_root *);

struct rb_node *rb_last(const struct rb_root *);

/* Fast replacement of a single node without remove/rebalance/add/rebalance */

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;

}

/* Cmus extensions */

static inline void rb_root_init(struct rb_root *root)

{

	root->rb_node = NULL;

}

static inline int rb_root_empty(struct rb_root *root)

{

	return RB_EMPTY_ROOT(root);

}

/**

 * rb_for_each        -       iterate over a rbtree

 * @pos:        the &struct rb_node to use as a loop counter.

 * @root:       the root for your rbtree.

 */

#define rb_for_each(pos, root) \

	for (pos = rb_first(root); pos; pos = rb_next(pos))

/**

 * rb_for_each_prev   -       iterate over a rbtree backwards

 * @pos:        the &struct rb_node to use as a loop counter.

 * @root:       the root for your rbtree.

 */

#define rb_for_each_prev(pos, root) \

	for (pos = rb_last(root); pos; pos = rb_prev(pos))

/**

 * rb_for_each_safe   -       iterate over a rbtree safe against removal of rbtree node

 * @pos:        the &struct rb_node to use as a loop counter.

 * @n:          another &struct rb_node to use as temporary storage

 * @root:       the root for your rbtree.

 */

#define rb_for_each_safe(pos, n, root) \

	for (pos = rb_first(root), n = pos ? rb_next(pos) : NULL; pos; \

		pos = n, n = pos ? rb_next(pos) : NULL)

/**

 * rb_for_each_entry        -       iterate over a rbtree of given type

 * @pos:        the &struct rb_node to use as a loop counter.

 * @t:          the type * to use as a loop counter.

 * @root:       the root for your rbtree.

 * @member:	the name of the rb_node-struct within the struct.

 */

#define rb_for_each_entry(t, pos, root, member) \

	for (pos = rb_first(root), t = pos ? rb_entry(pos, __typeof__(*t), member) : NULL; \

		pos; pos = rb_next(pos), t = pos ? rb_entry(pos, __typeof__(*t), member) : NULL)

/**

 * rb_for_each_entry_reverse        -       iterate backwards over a rbtree of given type

 * @pos:        the &struct rb_node to use as a loop counter.

 * @t:          the type * to use as a loop counter.

 * @root:       the root for your rbtree.

 * @member:	the name of the rb_node-struct within the struct.

 */

#define rb_for_each_entry_reverse(t, pos, root, member) \

	for (pos = rb_last(root), t = pos ? rb_entry(pos, __typeof__(*t), member) : NULL; \

		pos; pos = rb_prev(pos), t = pos ? rb_entry(pos, __typeof__(*t), member) : NULL)

#endif	/* _LINUX_RBTREE_H */