rbtree.h revision e0ed7404719a9ddd2ba427a80db5365c8bad18c0 
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  in two steps: First, the code must insert the element in order as a red leaf
29  in the tree, and then the support library function rb_insert_color() must
30  be called. Such function will do the not trivial work to rebalance the
31  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
97#include <stdlib.h>
98
99#undef offsetof
100#ifdef __compiler_offsetof
101#define offsetof(TYPE,MEMBER) __compiler_offsetof(TYPE,MEMBER)
102#else
103#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
104#endif
105
106#define container_of(ptr, type, member) ({			\
107	const __typeof__( ((type *)0)->member ) *__mptr = (ptr);	\
108	(type *)( (char *)__mptr - offsetof(type,member) );})
109
110struct rb_node
111{
112	unsigned long  rb_parent_color;
113#define	RB_RED		0
114#define	RB_BLACK	1
115	struct rb_node *rb_right;
116	struct rb_node *rb_left;
117} __attribute__((aligned(sizeof(long))));
118    /* The alignment might seem pointless, but allegedly CRIS needs it */
119
120struct rb_root
121{
122	struct rb_node *rb_node;
123};
124
125
126#define ext2fs_rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
127#define ext2fs_rb_color(r)   ((r)->rb_parent_color & 1)
128#define ext2fs_rb_is_red(r)   (!ext2fs_rb_color(r))
129#define ext2fs_rb_is_black(r) ext2fs_rb_color(r)
130#define ext2fs_rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
131#define ext2fs_rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)
132
133static inline void ext2fs_rb_set_parent(struct rb_node *rb, struct rb_node *p)
134{
135	rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
136}
137static inline void ext2fs_rb_set_color(struct rb_node *rb, int color)
138{
139	rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
140}
141
142#define RB_ROOT	(struct rb_root) { NULL, }
143#define	ext2fs_rb_entry(ptr, type, member) container_of(ptr, type, member)
144
145#define EXT2FS_RB_EMPTY_ROOT(root)	((root)->rb_node == NULL)
146#define EXT2FS_RB_EMPTY_NODE(node)	(ext2fs_rb_parent(node) == node)
147#define EXT2FS_RB_CLEAR_NODE(node)	(ext2fs_rb_set_parent(node, node))
148
149extern void ext2fs_rb_insert_color(struct rb_node *, struct rb_root *);
150extern void ext2fs_rb_erase(struct rb_node *, struct rb_root *);
151
152typedef void (*rb_augment_f)(struct rb_node *node, void *data);
153
154extern void ext2fs_rb_augment_insert(struct rb_node *node,
155			      rb_augment_f func, void *data);
156extern struct rb_node *ext2fs_rb_augment_erase_begin(struct rb_node *node);
157extern void ext2fs_rb_augment_erase_end(struct rb_node *node,
158				 rb_augment_f func, void *data);
159
160/* Find logical next and previous nodes in a tree */
161extern struct rb_node *ext2fs_rb_next(struct rb_node *);
162extern struct rb_node *ext2fs_rb_prev(struct rb_node *);
163extern struct rb_node *ext2fs_rb_first(const struct rb_root *);
164extern struct rb_node *ext2fs_rb_last(const struct rb_root *);
165
166/* Fast replacement of a single node without remove/rebalance/add/rebalance */
167extern void ext2fs_rb_replace_node(struct rb_node *victim, struct rb_node *new,
168				 struct rb_root *root);
169
170static inline void ext2fs_rb_link_node(struct rb_node * node,
171				     struct rb_node * parent,
172				     struct rb_node ** rb_link)
173{
174	node->rb_parent_color = (unsigned long )parent;
175	node->rb_left = node->rb_right = NULL;
176
177	*rb_link = node;
178}
179
180#endif	/* _LINUX_RBTREE_H */
181