library/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   linux/include/linux/rbtree.h
  16
  17   To use rbtrees you'll have to implement your own insert and search cores.
  18   This will avoid us to use callbacks and to drop drammatically performances.
  19   I know it's not the cleaner way,  but in C (not in C++) to get
  20   performances and genericity...
  21
  22   Some example of insert and search follows here. The search is a plain
  23   normal search over an ordered tree. The insert instead must be implemented
  24   int two steps: as first thing the code must insert the element in
  25   order as a red leaf in the tree, then the support library function
  26   rb_insert_color() must be called. Such function will do the
  27   not trivial work to rebalance the rbtree if necessary.
  28
  29 -----------------------------------------------------------------------
  30 static inline struct page * rb_search_page_cache(struct inode * inode,
  31                                                  unsigned long offset)
  32 {
  33         struct rb_node * n = inode->i_rb_page_cache.rb_node;
  34         struct page * page;
  35
  36         while (n)
  37         {
  38                 page = rb_entry(n, struct page, rb_page_cache);
  39
  40                 if (offset < page->offset)
  41                         n = n->rb_left;
  42                 else if (offset > page->offset)
  43                         n = n->rb_right;
  44                 else
  45                         return page;
  46         }
  47         return NULL;
  48 }
  49
  50 static inline struct page * __rb_insert_page_cache(struct inode * inode,
  51                                                    unsigned long offset,
  52                                                    struct rb_node * node)
  53 {
  54         struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
  55         struct rb_node * parent = NULL;
  56         struct page * page;
  57
  58         while (*p)
  59         {
  60                 parent = *p;
  61                 page = rb_entry(parent, struct page, rb_page_cache);
  62
  63                 if (offset < page->offset)
  64                         p = &(*p)->rb_left;
  65                 else if (offset > page->offset)
  66                         p = &(*p)->rb_right;
  67                 else
  68                         return page;
  69         }
  70
  71         rb_link_node(node, parent, p);
  72
  73         return NULL;
  74 }
  75
  76 static inline struct page * rb_insert_page_cache(struct inode * inode,
  77                                                  unsigned long offset,
  78                                                  struct rb_node * node)
  79 {
  80         struct page * ret;
  81         if ((ret = __rb_insert_page_cache(inode, offset, node)))
  82                 goto out;
  83         rb_insert_color(node, &inode->i_rb_page_cache);
  84  out:
  85         return ret;
  86 }
  87 -----------------------------------------------------------------------
  88 */
  89
  90 #ifndef __DNET_RBTREE_H
  91 #define __DNET_RBTREE_H
  92
  93 #ifdef __cplusplus
  94 extern "C" {
  95 #endif
  96
  97 struct rb_node
  98 {
  99         unsigned long  rb_parent_color;
 100 #define RB_RED          0
 101 #define RB_BLACK        1
 102         struct rb_node *rb_right;
 103         struct rb_node *rb_left;
 104 } __attribute__((aligned(sizeof(long))));
 105     /* The alignment might seem pointless, but allegedly CRIS needs it */
 106
 107 struct rb_root
 108 {
 109         struct rb_node *rb_node;
 110 };
 111
 112
 113 #define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
 114 #define rb_color(r)   ((r)->rb_parent_color & 1)
 115 #define rb_is_red(r)   (!rb_color(r))
 116 #define rb_is_black(r) rb_color(r)
 117 #define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
 118 #define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)
 119
 120 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
 121 {
 122         rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
 123 }
 124 static inline void rb_set_color(struct rb_node *rb, int color)
 125 {
 126         rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
 127 }
 128
 129 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 130
 131 #define container_of(ptr, type, member) ({                      \
 132         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 133         (type *)( (char *)__mptr - offsetof(type,member) );})
 134
 135 #define RB_ROOT (struct rb_root) { NULL, }
 136 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
 137
 138 #define RB_EMPTY_ROOT(root)     ((root)->rb_node == NULL)
 139 #define RB_EMPTY_NODE(node)     (rb_parent(node) == node)
 140 #define RB_CLEAR_NODE(node)     (rb_set_parent(node, node))
 141
 142 extern void rb_insert_color(struct rb_node *, struct rb_root *);
 143 extern void rb_erase(struct rb_node *, struct rb_root *);
 144
 145 /* Find logical next and previous nodes in a tree */
 146 extern struct rb_node *rb_next(struct rb_node *);
 147 extern struct rb_node *rb_prev(struct rb_node *);
 148 extern struct rb_node *rb_first(struct rb_root *);
 149 extern struct rb_node *rb_last(struct rb_root *);
 150
 151 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
 152 extern void rb_replace_node(struct rb_node *victim, struct rb_node *newp,
 153                             struct rb_root *root);
 154
 155 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
 156                                 struct rb_node ** rb_link)
 157 {
 158         node->rb_parent_color = (unsigned long )parent;
 159         node->rb_left = node->rb_right = NULL;
 160
 161         *rb_link = node;
 162 }
 163
 164 #ifdef __cplusplus
 165 }
 166 #endif
 167
 168 #endif  /* __DNET_RBTREE_H */