1 /* $NetBSD: interval_tree.h,v 1.14 2023/05/01 09:41:55 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2018 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Taylor R. Campbell.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 /*
33 * XXX WARNING: This does not actually implement interval trees -- it
34 * only implements trees of intervals. In particular, it does not
35 * support finding all intervals that contain a given point, or that
36 * intersect with a given interval. Another way to look at it is that
37 * this is an interval tree restricted to nonoverlapping intervals.
38 */
39
40 #ifndef _LINUX_INTERVAL_TREE_H_
41 #define _LINUX_INTERVAL_TREE_H_
42
43 #include <linux/rbtree.h>
44
45 struct interval_tree_node {
46 struct rb_node rb;
47 unsigned long start; /* inclusive */
48 unsigned long last; /* inclusive */
49 };
50
51 static inline int
interval_tree_compare_nodes(void * cookie,const void * va,const void * vb)52 interval_tree_compare_nodes(void *cookie, const void *va, const void *vb)
53 {
54 const struct interval_tree_node *na = va;
55 const struct interval_tree_node *nb = vb;
56
57 if (na->start < nb->start)
58 return -1;
59 if (na->start > nb->start)
60 return +1;
61 if (na->last < nb->last)
62 return -1;
63 if (na->last > nb->last)
64 return +1;
65 return 0;
66 }
67
68 static inline int
interval_tree_compare_key(void * cookie,const void * vn,const void * vk)69 interval_tree_compare_key(void *cookie, const void *vn, const void *vk)
70 {
71 const struct interval_tree_node *n = vn;
72 const unsigned long *k = vk;
73
74 if (n->start < *k)
75 return -1;
76 if (*k < n->start)
77 return +1;
78 return 0;
79 }
80
81 static const rb_tree_ops_t interval_tree_ops = {
82 .rbto_compare_nodes = interval_tree_compare_nodes,
83 .rbto_compare_key = interval_tree_compare_key,
84 .rbto_node_offset = offsetof(struct interval_tree_node, rb),
85 };
86
87 static inline void
interval_tree_init(struct rb_root_cached * root)88 interval_tree_init(struct rb_root_cached *root)
89 {
90
91 rb_tree_init(&root->rb_root.rbr_tree, &interval_tree_ops);
92 }
93
94 static inline void
interval_tree_insert(struct interval_tree_node * node,struct rb_root_cached * root)95 interval_tree_insert(struct interval_tree_node *node,
96 struct rb_root_cached *root)
97 {
98 struct interval_tree_node *collision __diagused;
99
100 collision = rb_tree_insert_node(&root->rb_root.rbr_tree, node);
101 KASSERT(collision == node);
102 }
103
104 static inline void
interval_tree_remove(struct interval_tree_node * node,struct rb_root_cached * root)105 interval_tree_remove(struct interval_tree_node *node,
106 struct rb_root_cached *root)
107 {
108
109 rb_tree_remove_node(&root->rb_root.rbr_tree, node);
110 }
111
112 static inline struct interval_tree_node *
interval_tree_iter_first(struct rb_root_cached * root,unsigned long start,unsigned long last)113 interval_tree_iter_first(struct rb_root_cached *root, unsigned long start,
114 unsigned long last)
115 {
116 struct interval_tree_node *node;
117
118 node = rb_tree_find_node_geq(&root->rb_root.rbr_tree, &start);
119 if (node == NULL)
120 return NULL;
121 if (last < node->start)
122 return NULL;
123 KASSERT(node->start <= last);
124 KASSERT(node->last >= start);
125
126 return node;
127 }
128
129 /*
130 * XXX Linux's interval_tree_iter_next doesn't take the root as an
131 * argument, which makes this difficult. So we'll just patch those
132 * uses.
133 */
134 static inline struct interval_tree_node *
interval_tree_iter_next(struct rb_root_cached * root,struct interval_tree_node * node,unsigned long start,unsigned long last)135 interval_tree_iter_next(struct rb_root_cached *root,
136 struct interval_tree_node *node, unsigned long start, unsigned long last)
137 {
138 struct interval_tree_node *next;
139
140 KASSERT(node != NULL);
141 next = rb_tree_iterate(&root->rb_root.rbr_tree, node, RB_DIR_RIGHT);
142 if (next == NULL)
143 return NULL;
144 if (last < next->start)
145 return NULL;
146 KASSERT(next->start <= last);
147 KASSERT(next->last >= start);
148
149 return next;
150 }
151
152 #endif /* _LINUX_INTERVAL_TREE_H_ */
153