Linux/include/linux/rbtree.h

  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   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 <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 #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 static inline void rb_init_node(struct rb_node *rb)
140 {
141         rb->rb_parent_color = 0;
142         rb->rb_right = NULL;
143         rb->rb_left = NULL;
144         RB_CLEAR_NODE(rb);
145 }
146 
147 extern void rb_insert_color(struct rb_node *, struct rb_root *);
148 extern void rb_erase(struct rb_node *, struct rb_root *);
149 
150 typedef void (*rb_augment_f)(struct rb_node *node, void *data);
151 
152 extern void rb_augment_insert(struct rb_node *node,
153                               rb_augment_f func, void *data);
154 extern struct rb_node *rb_augment_erase_begin(struct rb_node *node);
155 extern void rb_augment_erase_end(struct rb_node *node,
156                                  rb_augment_f func, void *data);
157 
158 /* Find logical next and previous nodes in a tree */
159 extern struct rb_node *rb_next(const struct rb_node *);
160 extern struct rb_node *rb_prev(const struct rb_node *);
161 extern struct rb_node *rb_first(const struct rb_root *);
162 extern struct rb_node *rb_last(const struct rb_root *);
163 
164 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
165 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 
166                             struct rb_root *root);
167 
168 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
169                                 struct rb_node ** rb_link)
170 {
171         node->rb_parent_color = (unsigned long )parent;
172         node->rb_left = node->rb_right = NULL;
173 
174         *rb_link = node;
175 }
176 
177 #endif  /* _LINUX_RBTREE_H */
178

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