Home | History | Annotate | Line # | Download | only in linux 
      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
     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
     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
     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
     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
    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 *
    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 *
    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