src/shared/libosmocore/include/osmocom/core/linuxrbtree.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 _LINUX_RBTREE_H
  91 #define _LINUX_RBTREE_H
  92
  93 #include <stdlib.h>
  94
  95 struct rb_node
  96 {
  97         unsigned long  rb_parent_color;
  98 #define RB_RED          0
  99 #define RB_BLACK        1
 100         struct rb_node *rb_right;
 101         struct rb_node *rb_left;
 102 } __attribute__((aligned(sizeof(long))));
 103     /* The alignment might seem pointless, but allegedly CRIS needs it */
 104
 105 struct rb_root
 106 {
 107         struct rb_node *rb_node;
 108 };
 109
 110
 111 #define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
 112 #define rb_color(r)   ((r)->rb_parent_color & 1)
 113 #define rb_is_red(r)   (!rb_color(r))
 114 #define rb_is_black(r) rb_color(r)
 115 #define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
 116 #define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)
 117
 118 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
 119 {
 120         rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
 121 }
 122 static inline void rb_set_color(struct rb_node *rb, int color)
 123 {
 124         rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
 125 }
 126
 127 #define RB_ROOT { NULL, }
 128 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
 129
 130 #define RB_EMPTY_ROOT(root)     ((root)->rb_node == NULL)
 131 #define RB_EMPTY_NODE(node)     (rb_parent(node) == node)
 132 #define RB_CLEAR_NODE(node)     (rb_set_parent(node, node))
 133
 134 extern void rb_insert_color(struct rb_node *, struct rb_root *);
 135 extern void rb_erase(struct rb_node *, struct rb_root *);
 136
 137 /* Find logical next and previous nodes in a tree */
 138 extern struct rb_node *rb_next(const struct rb_node *);
 139 extern struct rb_node *rb_prev(const struct rb_node *);
 140 extern struct rb_node *rb_first(const struct rb_root *);
 141 extern struct rb_node *rb_last(const struct rb_root *);
 142
 143 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
 144 extern void rb_replace_node(struct rb_node *victim, struct rb_node *_new,
 145                             struct rb_root *root);
 146
 147 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
 148                                 struct rb_node ** rb_link)
 149 {
 150         node->rb_parent_color = (unsigned long )parent;
 151         node->rb_left = node->rb_right = NULL;
 152
 153         *rb_link = node;
 154 }
 155
 156 #endif  /* _LINUX_RBTREE_H */