1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_INTERVAL_TREE_H
3#define _LINUX_INTERVAL_TREE_H
4
5#include <linux/rbtree.h>
6
7struct interval_tree_node {
8	struct rb_node rb;
9	unsigned long start;	/* Start of interval */
10	unsigned long last;	/* Last location _in_ interval */
11	unsigned long __subtree_last;
12};
13
14extern void
15interval_tree_insert(struct interval_tree_node *node,
16		     struct rb_root_cached *root);
17
18extern void
19interval_tree_remove(struct interval_tree_node *node,
20		     struct rb_root_cached *root);
21
22extern struct interval_tree_node *
23interval_tree_iter_first(struct rb_root_cached *root,
24			 unsigned long start, unsigned long last);
25
26extern struct interval_tree_node *
27interval_tree_iter_next(struct interval_tree_node *node,
28			unsigned long start, unsigned long last);
29
30/**
31 * struct interval_tree_span_iter - Find used and unused spans.
32 * @start_hole: Start of an interval for a hole when is_hole == 1
33 * @last_hole: Inclusive end of an interval for a hole when is_hole == 1
34 * @start_used: Start of a used interval when is_hole == 0
35 * @last_used: Inclusive end of a used interval when is_hole == 0
36 * @is_hole: 0 == used, 1 == is_hole, -1 == done iteration
37 *
38 * This iterator travels over spans in an interval tree. It does not return
39 * nodes but classifies each span as either a hole, where no nodes intersect, or
40 * a used, which is fully covered by nodes. Each iteration step toggles between
41 * hole and used until the entire range is covered. The returned spans always
42 * fully cover the requested range.
43 *
44 * The iterator is greedy, it always returns the largest hole or used possible,
45 * consolidating all consecutive nodes.
46 *
47 * Use interval_tree_span_iter_done() to detect end of iteration.
48 */
49struct interval_tree_span_iter {
50	/* private: not for use by the caller */
51	struct interval_tree_node *nodes[2];
52	unsigned long first_index;
53	unsigned long last_index;
54
55	/* public: */
56	union {
57		unsigned long start_hole;
58		unsigned long start_used;
59	};
60	union {
61		unsigned long last_hole;
62		unsigned long last_used;
63	};
64	int is_hole;
65};
66
67void interval_tree_span_iter_first(struct interval_tree_span_iter *state,
68				   struct rb_root_cached *itree,
69				   unsigned long first_index,
70				   unsigned long last_index);
71void interval_tree_span_iter_advance(struct interval_tree_span_iter *iter,
72				     struct rb_root_cached *itree,
73				     unsigned long new_index);
74void interval_tree_span_iter_next(struct interval_tree_span_iter *state);
75
76static inline bool
77interval_tree_span_iter_done(struct interval_tree_span_iter *state)
78{
79	return state->is_hole == -1;
80}
81
82#define interval_tree_for_each_span(span, itree, first_index, last_index)      \
83	for (interval_tree_span_iter_first(span, itree,                        \
84					   first_index, last_index);           \
85	     !interval_tree_span_iter_done(span);                              \
86	     interval_tree_span_iter_next(span))
87
88#endif	/* _LINUX_INTERVAL_TREE_H */
89