1 /*
2 * Copyright 2013 Marek Olšák <maraeo@gmail.com>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * on the rights to use, copy, modify, merge, publish, distribute, sub
8 * license, and/or sell copies of the Software, and to permit persons to whom
9 * the Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
19 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
20 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
21 * USE OR OTHER DEALINGS IN THE SOFTWARE. */
22
23 /**
24 * @file
25 * 1D integer range, capable of the union and intersection operations.
26 *
27 * It only maintains a single interval which is extended when the union is
28 * done. This implementation is partially thread-safe (readers are not
29 * protected by a lock).
30 *
31 * @author Marek Olšák
32 */
33
34 #ifndef U_RANGE_H
35 #define U_RANGE_H
36
37 #include "os/os_thread.h"
38
39 #include "util/u_math.h"
40
41 struct util_range {
42 unsigned start; /* inclusive */
43 unsigned end; /* exclusive */
44
45 /* for the range to be consistent with multiple contexts: */
46 mtx_t write_mutex;
47 };
48
49
50 static inline void
util_range_set_empty(struct util_range * range)51 util_range_set_empty(struct util_range *range)
52 {
53 range->start = ~0;
54 range->end = 0;
55 }
56
57 /* This is like a union of two sets. */
58 static inline void
util_range_add(struct util_range * range,unsigned start,unsigned end)59 util_range_add(struct util_range *range, unsigned start, unsigned end)
60 {
61 if (start < range->start || end > range->end) {
62 mtx_lock(&range->write_mutex);
63 range->start = MIN2(start, range->start);
64 range->end = MAX2(end, range->end);
65 mtx_unlock(&range->write_mutex);
66 }
67 }
68
69 static inline boolean
util_ranges_intersect(struct util_range * range,unsigned start,unsigned end)70 util_ranges_intersect(struct util_range *range, unsigned start, unsigned end)
71 {
72 return MAX2(start, range->start) < MIN2(end, range->end);
73 }
74
75
76 /* Init/deinit */
77
78 static inline void
util_range_init(struct util_range * range)79 util_range_init(struct util_range *range)
80 {
81 (void) mtx_init(&range->write_mutex, mtx_plain);
82 util_range_set_empty(range);
83 }
84
85 static inline void
util_range_destroy(struct util_range * range)86 util_range_destroy(struct util_range *range)
87 {
88 mtx_destroy(&range->write_mutex);
89 }
90
91 #endif
92