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