1/*
2  Red Black Trees
3  (C) 1999  Andrea Arcangeli <andrea@suse.de>
4
5  This program is free software; you can redistribute it and/or modify
6  it under the terms of the GNU General Public License as published by
7  the Free Software Foundation; either version 2 of the License, or
8  (at your option) any later version.
9
10  This program is distributed in the hope that it will be useful,
11  but WITHOUT ANY WARRANTY; without even the implied warranty of
12  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  GNU General Public License for more details.
14
15  You should have received a copy of the GNU General Public License
16  along with this program; if not, write to the Free Software
17  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18
19  linux/include/linux/rbtree.h
20
21  To use rbtrees you'll have to implement your own insert and search cores.
22  This will avoid us to use callbacks and to drop drammatically performances.
23  I know it's not the cleaner way,  but in C (not in C++) to get
24  performances and genericity...
25
26  Some example of insert and search follows here. The search is a plain
27  normal search over an ordered tree. The insert instead must be implemented
28  int two steps: as first thing the code must insert the element in
29  order as a red leaf in the tree, then the support library function
30  rb_insert_color() must be called. Such function will do the
31  not trivial work to rebalance the rbtree if necessary.
32
33-----------------------------------------------------------------------
34static inline struct page * rb_search_page_cache(struct inode * inode,
35						 unsigned long offset)
36{
37	struct rb_node * n = inode->i_rb_page_cache.rb_node;
38	struct page * page;
39
40	while (n)
41	{
42		page = rb_entry(n, struct page, rb_page_cache);
43
44		if (offset < page->offset)
45			n = n->rb_left;
46		else if (offset > page->offset)
47			n = n->rb_right;
48		else
49			return page;
50	}
51	return NULL;
52}
53
54static inline struct page * __rb_insert_page_cache(struct inode * inode,
55						   unsigned long offset,
56						   struct rb_node * node)
57{
58	struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
59	struct rb_node * parent = NULL;
60	struct page * page;
61
62	while (*p)
63	{
64		parent = *p;
65		page = rb_entry(parent, struct page, rb_page_cache);
66
67		if (offset < page->offset)
68			p = &(*p)->rb_left;
69		else if (offset > page->offset)
70			p = &(*p)->rb_right;
71		else
72			return page;
73	}
74
75	rb_link_node(node, parent, p);
76
77	return NULL;
78}
79
80static inline struct page * rb_insert_page_cache(struct inode * inode,
81						 unsigned long offset,
82						 struct rb_node * node)
83{
84	struct page * ret;
85	if ((ret = __rb_insert_page_cache(inode, offset, node)))
86		goto out;
87	rb_insert_color(node, &inode->i_rb_page_cache);
88 out:
89	return ret;
90}
91-----------------------------------------------------------------------
92*/
93
94#ifndef	_LINUX_RBTREE_H
95#define	_LINUX_RBTREE_H
96
97struct rb_node
98{
99	unsigned long  rb_parent_color;
100	struct rb_node *rb_right;
101	struct rb_node *rb_left;
102};
103
104struct rb_root
105{
106	struct rb_node *rb_node;
107};
108
109
110#define RB_ROOT	(struct rb_root) { NULL, }
111
112#if 0
113#define	rb_entry(ptr, type, member) container_of(ptr, type, member)
114#endif
115
116void rb_insert_color(struct rb_node *, struct rb_root *);
117void rb_erase(struct rb_node *, struct rb_root *);
118
119/* Find logical next and previous nodes in a tree */
120struct rb_node *rb_next(struct rb_node *);
121struct rb_node *rb_prev(struct rb_node *);
122struct rb_node *rb_first(struct rb_root *);
123struct rb_node *rb_last(struct rb_root *);
124
125/* Fast replacement of a single node without remove/rebalance/add/rebalance */
126extern void rb_replace_node(struct rb_node *victim, struct rb_node *new_node,
127			    struct rb_root *root);
128
129void rb_link_node(struct rb_node * node, struct rb_node * parent,
130		  struct rb_node ** rb_link);
131
132#endif	/* _LINUX_RBTREE_H */
133