u_range.h revision b8e80941 
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
41struct 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
50static inline void
51util_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. */
58static inline void
59util_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
69static inline boolean
70util_ranges_intersect(const struct util_range *range,
71                      unsigned start, unsigned end)
72{
73   return MAX2(start, range->start) < MIN2(end, range->end);
74}
75
76
77/* Init/deinit */
78
79static inline void
80util_range_init(struct util_range *range)
81{
82   (void) mtx_init(&range->write_mutex, mtx_plain);
83   util_range_set_empty(range);
84}
85
86static inline void
87util_range_destroy(struct util_range *range)
88{
89   mtx_destroy(&range->write_mutex);
90}
91
92#endif
93