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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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 dramatically 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 -----------------------------------------------------------------------
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 #include <stdint.h>
99 #include "compiler.h"
100
101 struct rb_node
102 {
103 uintptr_t rb_parent_color;
104 #define RB_RED 0
105 #define RB_BLACK 1
106 struct rb_node *rb_right;
107 struct rb_node *rb_left;
108 } __attribute__((aligned(sizeof(long))));
109 /* The alignment might seem pointless, but allegedly CRIS needs it */
110
111 struct rb_root
112 {
113 struct rb_node *rb_node;
114 };
115
116
117 #define ext2fs_rb_parent(r) ((struct rb_node *)((r)->rb_parent_color & ~3))
118 #define ext2fs_rb_color(r) ((r)->rb_parent_color & 1)
119 #define ext2fs_rb_is_red(r) (!ext2fs_rb_color(r))
120 #define ext2fs_rb_is_black(r) ext2fs_rb_color(r)
121 #define ext2fs_rb_set_red(r) do { (r)->rb_parent_color &= ~1; } while (0)
122 #define ext2fs_rb_set_black(r) do { (r)->rb_parent_color |= 1; } while (0)
123
ext2fs_rb_set_parent(struct rb_node * rb,struct rb_node * p)124 static inline void ext2fs_rb_set_parent(struct rb_node *rb, struct rb_node *p)
125 {
126 rb->rb_parent_color = (rb->rb_parent_color & 3) | (uintptr_t)p;
127 }
ext2fs_rb_set_color(struct rb_node * rb,int color)128 static inline void ext2fs_rb_set_color(struct rb_node *rb, int color)
129 {
130 rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
131 }
132
133 #define RB_ROOT (struct rb_root) { NULL, }
134 #define ext2fs_rb_entry(ptr, type, member) container_of(ptr, type, member)
135
ext2fs_rb_empty_root(struct rb_root * root)136 static inline int ext2fs_rb_empty_root(struct rb_root *root)
137 {
138 return root->rb_node == NULL;
139 }
140
ext2fs_rb_empty_node(struct rb_node * node)141 static inline int ext2fs_rb_empty_node(struct rb_node *node)
142 {
143 return ext2fs_rb_parent(node) == node;
144 }
145
ext2fs_rb_clear_node(struct rb_node * node)146 static inline void ext2fs_rb_clear_node(struct rb_node *node)
147 {
148 ext2fs_rb_set_parent(node, node);
149 }
150
151 extern void ext2fs_rb_insert_color(struct rb_node *, struct rb_root *);
152 extern void ext2fs_rb_erase(struct rb_node *, struct rb_root *);
153
154 /* Find logical next and previous nodes in a tree */
155 extern struct rb_node *ext2fs_rb_next(struct rb_node *);
156 extern struct rb_node *ext2fs_rb_prev(struct rb_node *);
157 extern struct rb_node *ext2fs_rb_first(const struct rb_root *);
158 extern struct rb_node *ext2fs_rb_last(const struct rb_root *);
159
160 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
161 extern void ext2fs_rb_replace_node(struct rb_node *victim, struct rb_node *new,
162 struct rb_root *root);
163
ext2fs_rb_link_node(struct rb_node * node,struct rb_node * parent,struct rb_node ** rb_link)164 static inline void ext2fs_rb_link_node(struct rb_node * node,
165 struct rb_node * parent,
166 struct rb_node ** rb_link)
167 {
168 node->rb_parent_color = (uintptr_t)parent;
169 node->rb_left = node->rb_right = NULL;
170
171 *rb_link = node;
172 }
173
174 #endif /* _LINUX_RBTREE_H */
175