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1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3   Red Black Trees
4   (C) 1999  Andrea Arcangeli <andrea@suse.de>
5 
6   linux/include/linux/rbtree.h
7 
8   To use rbtrees you'll have to implement your own insert and search cores.
9   This will avoid us to use callbacks and to drop drammatically performances.
10   I know it's not the cleaner way,  but in C (not in C++) to get
11   performances and genericity...
12 
13   See Documentation/rbtree.txt for documentation and samples.
14 */
15 
16 #ifndef	_LINUX_RBTREE_H
17 #define	_LINUX_RBTREE_H
18 
19 #ifndef __UBOOT__
20 #include <linux/kernel.h>
21 #endif
22 #include <linux/stddef.h>
23 
24 struct rb_node {
25 	unsigned long  __rb_parent_color;
26 	struct rb_node *rb_right;
27 	struct rb_node *rb_left;
28 } __attribute__((aligned(sizeof(long))));
29     /* The alignment might seem pointless, but allegedly CRIS needs it */
30 
31 struct rb_root {
32 	struct rb_node *rb_node;
33 };
34 
35 
36 #define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))
37 
38 #define RB_ROOT	(struct rb_root) { NULL, }
39 #define	rb_entry(ptr, type, member) container_of(ptr, type, member)
40 
41 #define RB_EMPTY_ROOT(root)  ((root)->rb_node == NULL)
42 
43 /* 'empty' nodes are nodes that are known not to be inserted in an rbree */
44 #define RB_EMPTY_NODE(node)  \
45 	((node)->__rb_parent_color == (unsigned long)(node))
46 #define RB_CLEAR_NODE(node)  \
47 	((node)->__rb_parent_color = (unsigned long)(node))
48 
49 
50 extern void rb_insert_color(struct rb_node *, struct rb_root *);
51 extern void rb_erase(struct rb_node *, struct rb_root *);
52 
53 
54 /* Find logical next and previous nodes in a tree */
55 extern struct rb_node *rb_next(const struct rb_node *);
56 extern struct rb_node *rb_prev(const struct rb_node *);
57 extern struct rb_node *rb_first(const struct rb_root *);
58 extern struct rb_node *rb_last(const struct rb_root *);
59 
60 /* Postorder iteration - always visit the parent after its children */
61 extern struct rb_node *rb_first_postorder(const struct rb_root *);
62 extern struct rb_node *rb_next_postorder(const struct rb_node *);
63 
64 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
65 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
66 			    struct rb_root *root);
67 
rb_link_node(struct rb_node * node,struct rb_node * parent,struct rb_node ** rb_link)68 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
69 				struct rb_node ** rb_link)
70 {
71 	node->__rb_parent_color = (unsigned long)parent;
72 	node->rb_left = node->rb_right = NULL;
73 
74 	*rb_link = node;
75 }
76 
77 #define rb_entry_safe(ptr, type, member) \
78 	({ typeof(ptr) ____ptr = (ptr); \
79 	   ____ptr ? rb_entry(____ptr, type, member) : NULL; \
80 	})
81 
82 /**
83  * rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of
84  * given type safe against removal of rb_node entry
85  *
86  * @pos:	the 'type *' to use as a loop cursor.
87  * @n:		another 'type *' to use as temporary storage
88  * @root:	'rb_root *' of the rbtree.
89  * @field:	the name of the rb_node field within 'type'.
90  */
91 #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
92 	for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
93 	     pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
94 			typeof(*pos), field); 1; }); \
95 	     pos = n)
96 
97 #endif	/* _LINUX_RBTREE_H */
98