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   See Documentation/rbtree.txt for documentation and samples.
  27 */
  28
  29 #ifndef _LINUX_RBTREE_H
  30 #define _LINUX_RBTREE_H
  31 #if BTRFS_FLAT_INCLUDES
  32 #include "kerncompat.h"
  33 #else
  34 #include <btrfs/kerncompat.h>
  35 #endif /* BTRFS_FLAT_INCLUDES */
  36
  37 #ifdef __cplusplus
  38 extern "C" {
  39 #endif
  40
  41 struct rb_node {
  42         unsigned long  __rb_parent_color;
  43         struct rb_node *rb_right;
  44         struct rb_node *rb_left;
  45 } __attribute__((aligned(sizeof(long))));
  46     /* The alignment might seem pointless, but allegedly CRIS needs it */
  47
  48 struct rb_root {
  49         struct rb_node *rb_node;
  50 };
  51
  52
  53 #define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))
  54
  55 #define RB_ROOT (struct rb_root) { NULL, }
  56 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
  57
  58 #define RB_EMPTY_ROOT(root)  ((root)->rb_node == NULL)
  59
  60 /* 'empty' nodes are nodes that are known not to be inserted in an rtbree */
  61 #define RB_EMPTY_NODE(node)  \
  62         ((node)->__rb_parent_color == (unsigned long)(node))
  63 #define RB_CLEAR_NODE(node)  \
  64         ((node)->__rb_parent_color = (unsigned long)(node))
  65
  66
  67 extern void rb_insert_color(struct rb_node *, struct rb_root *);
  68 extern void rb_erase(struct rb_node *, struct rb_root *);
  69
  70
  71 /* Find logical next and previous nodes in a tree */
  72 extern struct rb_node *rb_next(const struct rb_node *);
  73 extern struct rb_node *rb_prev(const struct rb_node *);
  74 extern struct rb_node *rb_first(const struct rb_root *);
  75 extern struct rb_node *rb_last(const struct rb_root *);
  76
  77 /* Postorder iteration - always visit the parent after its children */
  78 extern struct rb_node *rb_first_postorder(const struct rb_root *);
  79 extern struct rb_node *rb_next_postorder(const struct rb_node *);
  80
  81 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
  82 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new_node,
  83                             struct rb_root *root);
  84
  85 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
  86                                 struct rb_node ** rb_link)
  87 {
  88         node->__rb_parent_color = (unsigned long)parent;
  89         node->rb_left = node->rb_right = NULL;
  90
  91         *rb_link = node;
  92 }
  93
  94 #define rb_entry_safe(ptr, type, member) \
  95         ({ typeof(ptr) ____ptr = (ptr); \
  96            ____ptr ? rb_entry(____ptr, type, member) : NULL; \
  97         })
  98
  99 /**
 100  * rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of
 101  * given type safe against removal of rb_node entry
 102  *
 103  * @pos:        the 'type *' to use as a loop cursor.
 104  * @n:          another 'type *' to use as temporary storage
 105  * @root:       'rb_root *' of the rbtree.
 106  * @field:      the name of the rb_node field within 'type'.
 107  */
 108 #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
 109         for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
 110              pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
 111                         typeof(*pos), field); 1; }); \
 112              pos = n)
 113
 114 #ifdef __cplusplus
 115 }
 116 #endif
 117
 118 #endif  /* _LINUX_RBTREE_H */