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 <stdlib.h>
98
99 struct rb_node
100 {
101 unsigned long rb_parent_color;
102 #define RB_RED 0
103 #define RB_BLACK 1
104 struct rb_node *rb_right;
105 struct rb_node *rb_left;
106 };
107
108 struct rb_root
109 {
110 struct rb_node *rb_node;
111 };
112
113 #undef offsetof
114 #ifdef __compiler_offsetof
115 #define offsetof(TYPE,MEMBER) __compiler_offsetof(TYPE,MEMBER)
116 #else
117 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
118 #endif
119
120 #define container_of(ptr, type, member) ({ \
121 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
122 (type *)( (char *)__mptr - offsetof(type,member) );})
123
124 #define rb_parent(r) ((struct rb_node *)((r)->rb_parent_color & ~3))
125 #define rb_color(r) ((r)->rb_parent_color & 1)
126 #define rb_is_red(r) (!rb_color(r))
127 #define rb_is_black(r) rb_color(r)
128 #define rb_set_red(r) do { (r)->rb_parent_color &= ~1; } while (0)
129 #define rb_set_black(r) do { (r)->rb_parent_color |= 1; } while (0)
130
rb_set_parent(struct rb_node * rb,struct rb_node * p)131 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
132 {
133 rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
134 }
rb_set_color(struct rb_node * rb,int color)135 static inline void rb_set_color(struct rb_node *rb, int color)
136 {
137 rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
138 }
139
140 #define RB_ROOT (struct rb_root) { NULL, }
141 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
142
143 extern void rb_insert_color(struct rb_node *, struct rb_root *);
144 extern void rb_erase(struct rb_node *, struct rb_root *);
145
146 /* Find logical next and previous nodes in a tree */
147 extern struct rb_node *rb_next(struct rb_node *);
148 extern struct rb_node *rb_prev(struct rb_node *);
149 extern struct rb_node *rb_first(struct rb_root *);
150 extern struct rb_node *rb_last(struct rb_root *);
151
152 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
153 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
154 struct rb_root *root);
155
rb_link_node(struct rb_node * node,struct rb_node * parent,struct rb_node ** rb_link)156 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
157 struct rb_node ** rb_link)
158 {
159 node->rb_parent_color = (unsigned long )parent;
160 node->rb_left = node->rb_right = NULL;
161
162 *rb_link = node;
163 }
164
165 #endif /* _LINUX_RBTREE_H */
166