Line data Source code
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 1 : /* 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 :
123 : static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
124 : {
125 0 : rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
126 0 : }
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(const struct rb_node *);
144 : extern struct rb_node *rb_prev(const struct rb_node *);
145 : extern struct rb_node *rb_first(const struct rb_root *);
146 : extern struct rb_node *rb_last(const 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 :
152 : static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
153 : struct rb_node ** rb_link)
154 : {
155 0 : node->rb_parent_color = (unsigned long )parent;
156 0 : node->rb_left = node->rb_right = NULL;
157 :
158 0 : *rb_link = node;
159 0 : }
160 2 :
161 : #endif /* _LINUX_RBTREE_H */
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