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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 -----------------------------------------------------------------------
34 static 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 
54 static 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 
80 static 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 <linux/kernel.h>
98 #include <linux/stddef.h>
99 
100 struct rb_node
101 {
102 	unsigned long  rb_parent_color;
103 #define	RB_RED		0
104 #define	RB_BLACK	1
105 	struct rb_node *rb_right;
106 	struct rb_node *rb_left;
107 } __attribute__((aligned(sizeof(long))));
108     /* The alignment might seem pointless, but allegedly CRIS needs it */
109 
110 struct rb_root
111 {
112 	struct rb_node *rb_node;
113 };
114 
115 
116 #define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
117 #define rb_color(r)   ((r)->rb_parent_color & 1)
118 #define rb_is_red(r)   (!rb_color(r))
119 #define rb_is_black(r) rb_color(r)
120 #define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
121 #define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)
122 
rb_set_parent(struct rb_node * rb,struct rb_node * p)123 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
124 {
125 	rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
126 }
rb_set_color(struct rb_node * rb,int color)127 static inline void rb_set_color(struct rb_node *rb, int color)
128 {
129 	rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
130 }
131 
132 #define RB_ROOT	(struct rb_root) { NULL, }
133 #define	rb_entry(ptr, type, member) container_of(ptr, type, member)
134 
135 #define RB_EMPTY_ROOT(root)	((root)->rb_node == NULL)
136 #define RB_EMPTY_NODE(node)	(rb_parent(node) != node)
137 #define RB_CLEAR_NODE(node)	(rb_set_parent(node, node))
138 
139 extern void rb_insert_color(struct rb_node *, struct rb_root *);
140 extern void rb_erase(struct rb_node *, struct rb_root *);
141 
142 /* Find logical next and previous nodes in a tree */
143 extern struct rb_node *rb_next(struct rb_node *);
144 extern struct rb_node *rb_prev(struct rb_node *);
145 extern struct rb_node *rb_first(struct rb_root *);
146 extern struct rb_node *rb_last(struct rb_root *);
147 
148 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
149 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
150 			    struct rb_root *root);
151 
rb_link_node(struct rb_node * node,struct rb_node * parent,struct rb_node ** rb_link)152 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
153 				struct rb_node ** rb_link)
154 {
155 	node->rb_parent_color = (unsigned long )parent;
156 	node->rb_left = node->rb_right = NULL;
157 
158 	*rb_link = node;
159 }
160 
161 #endif	/* _LINUX_RBTREE_H */
162