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 : /* 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 : rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
126 : }
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 :
134 : /* Newer gcc versions take care of exporting this */
135 : #ifndef offsetof
136 : #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
137 : #endif
138 :
139 : #define container_of(ptr, type, member) ({ \
140 : const typeof( ((type *)0)->member ) *__mptr = (ptr); \
141 : (type *)( (char *)__mptr - offsetof(type,member) );})
142 :
143 : #define rb_entry(ptr, type, member) container_of(ptr, type, member)
144 :
145 : #define RB_EMPTY_ROOT(root) ((root)->rb_node == NULL)
146 : #define RB_EMPTY_NODE(node) (rb_parent(node) == node)
147 : #define RB_CLEAR_NODE(node) (rb_set_parent(node, node))
148 :
149 : extern void rb_insert_color(struct rb_node *, struct rb_root *);
150 : extern void rb_erase(struct rb_node *, struct rb_root *);
151 :
152 : /* Find logical next and previous nodes in a tree */
153 : extern struct rb_node *rb_next(struct rb_node *);
154 : extern struct rb_node *rb_prev(struct rb_node *);
155 : extern struct rb_node *rb_first(struct rb_root *);
156 : extern struct rb_node *rb_last(struct rb_root *);
157 :
158 : /* Postorder iteration - always visit the parent after its children */
159 : extern struct rb_node *rb_first_postorder(const struct rb_root *);
160 : extern struct rb_node *rb_next_postorder(const struct rb_node *);
161 :
162 : #define rb_entry_safe(ptr, type, member) \
163 : ({ typeof(ptr) ____ptr = (ptr); \
164 : ____ptr ? rb_entry(____ptr, type, member) : NULL; \
165 : })
166 :
167 : /**
168 : * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
169 : * given type allowing the backing memory of @pos to be invalidated
170 : *
171 : * @pos: the 'type *' to use as a loop cursor.
172 : * @n: another 'type *' to use as temporary storage
173 : * @root: 'rb_root *' of the rbtree.
174 : * @field: the name of the rb_node field within 'type'.
175 : *
176 : * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
177 : * list_for_each_entry_safe() and allows the iteration to continue independent
178 : * of changes to @pos by the body of the loop.
179 : *
180 : * Note, however, that it cannot handle other modifications that re-order the
181 : * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
182 : * rb_erase() may rebalance the tree, causing us to miss some nodes.
183 : */
184 : #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
185 : for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
186 : pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
187 : typeof(*pos), field); 1; }); \
188 : pos = n)
189 :
190 : /* Fast replacement of a single node without remove/rebalance/add/rebalance */
191 : extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
192 : struct rb_root *root);
193 :
194 : static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
195 : struct rb_node ** rb_link)
196 : {
197 2814638130 : node->rb_parent_color = (unsigned long )parent;
198 2814638130 : node->rb_left = node->rb_right = NULL;
199 :
200 2814638130 : *rb_link = node;
201 : }
202 :
203 : #endif /* _LINUX_RBTREE_H */
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