source: trunk/kernel/libk/rbtree.h @ 563

Last change on this file since 563 was 1, checked in by alain, 5 years ago

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