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  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.  
  32. #include <linux/kernel.h>
  33. #include <linux/stddef.h>
  34. #include <linux/rcupdate.h>
  35.  
  36. struct rb_node {
  37.         unsigned long  __rb_parent_color;
  38.         struct rb_node *rb_right;
  39.         struct rb_node *rb_left;
  40. } __attribute__((aligned(sizeof(long))));
  41.     /* The alignment might seem pointless, but allegedly CRIS needs it */
  42.  
  43. struct rb_root {
  44.         struct rb_node *rb_node;
  45. };
  46.  
  47.  
  48. #define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))
  49.  
  50. #define RB_ROOT (struct rb_root) { NULL, }
  51. #define rb_entry(ptr, type, member) container_of(ptr, type, member)
  52.  
  53. #define RB_EMPTY_ROOT(root)  ((root)->rb_node == NULL)
  54.  
  55. /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
  56. #define RB_EMPTY_NODE(node)  \
  57.         ((node)->__rb_parent_color == (unsigned long)(node))
  58. #define RB_CLEAR_NODE(node)  \
  59.         ((node)->__rb_parent_color = (unsigned long)(node))
  60.  
  61.  
  62. extern void rb_insert_color(struct rb_node *, struct rb_root *);
  63. extern void rb_erase(struct rb_node *, struct rb_root *);
  64.  
  65.  
  66. /* Find logical next and previous nodes in a tree */
  67. extern struct rb_node *rb_next(const struct rb_node *);
  68. extern struct rb_node *rb_prev(const struct rb_node *);
  69. extern struct rb_node *rb_first(const struct rb_root *);
  70. extern struct rb_node *rb_last(const struct rb_root *);
  71.  
  72. /* Postorder iteration - always visit the parent after its children */
  73. extern struct rb_node *rb_first_postorder(const struct rb_root *);
  74. extern struct rb_node *rb_next_postorder(const struct rb_node *);
  75.  
  76. /* Fast replacement of a single node without remove/rebalance/add/rebalance */
  77. extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
  78.                             struct rb_root *root);
  79.  
  80. static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
  81.                                 struct rb_node **rb_link)
  82. {
  83.         node->__rb_parent_color = (unsigned long)parent;
  84.         node->rb_left = node->rb_right = NULL;
  85.  
  86.         *rb_link = node;
  87. }
  88.  
  89. static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
  90.                                     struct rb_node **rb_link)
  91. {
  92.         node->__rb_parent_color = (unsigned long)parent;
  93.         node->rb_left = node->rb_right = NULL;
  94.  
  95.         rcu_assign_pointer(*rb_link, node);
  96. }
  97.  
  98. #define rb_entry_safe(ptr, type, member) \
  99.         ({ typeof(ptr) ____ptr = (ptr); \
  100.            ____ptr ? rb_entry(____ptr, type, member) : NULL; \
  101.         })
  102.  
  103. /**
  104.  * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
  105.  * given type allowing the backing memory of @pos to be invalidated
  106.  *
  107.  * @pos:        the 'type *' to use as a loop cursor.
  108.  * @n:          another 'type *' to use as temporary storage
  109.  * @root:       'rb_root *' of the rbtree.
  110.  * @field:      the name of the rb_node field within 'type'.
  111.  *
  112.  * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
  113.  * list_for_each_entry_safe() and allows the iteration to continue independent
  114.  * of changes to @pos by the body of the loop.
  115.  *
  116.  * Note, however, that it cannot handle other modifications that re-order the
  117.  * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
  118.  * rb_erase() may rebalance the tree, causing us to miss some nodes.
  119.  */
  120. #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
  121.         for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
  122.              pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
  123.                         typeof(*pos), field); 1; }); \
  124.              pos = n)
  125.  
  126. #endif  /* _LINUX_RBTREE_H */
  127.