1 /* $NetBSD: clock.h,v 1.4 2018/04/19 21:19:07 christos Exp $ */
2
3 /*-
4 * Copyright (c) 1996 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Gordon W. Ross
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 #ifndef _SYS_CLOCK_H_
33 #define _SYS_CLOCK_H_
34
35 /* Some handy constants. */
36 #define SECS_PER_MINUTE 60
37 #define SECS_PER_HOUR 3600
38 #define SECS_PER_DAY 86400
39 #define DAYS_PER_COMMON_YEAR 365
40 #define DAYS_PER_LEAP_YEAR 366
41 #define SECS_PER_COMMON_YEAR (SECS_PER_DAY * DAYS_PER_COMMON_YEAR)
42 #define SECS_PER_LEAP_YEAR (SECS_PER_DAY * DAYS_PER_LEAP_YEAR)
43
44 /* Traditional POSIX base year */
45 #define POSIX_BASE_YEAR 1970
46
47 /* Some handy functions */
48 static __inline int
days_in_month(int m)49 days_in_month(int m)
50 {
51 switch (m) {
52 case 2:
53 return 28;
54 case 4: case 6: case 9: case 11:
55 return 30;
56 case 1: case 3: case 5: case 7: case 8: case 10: case 12:
57 return 31;
58 default:
59 return -1;
60 }
61 }
62
63 /*
64 * This inline avoids some unnecessary modulo operations
65 * as compared with the usual macro:
66 * ( ((year % 4) == 0 &&
67 * (year % 100) != 0) ||
68 * ((year % 400) == 0) )
69 * It is otherwise equivalent.
70 */
71 static __inline int
is_leap_year(uint64_t year)72 is_leap_year(uint64_t year)
73 {
74 if ((year & 3) != 0)
75 return 0;
76
77 if (__predict_false((year % 100) != 0))
78 return 1;
79
80 return __predict_false((year % 400) == 0);
81 }
82
83 static __inline int
days_per_year(uint64_t year)84 days_per_year(uint64_t year)
85 {
86 return is_leap_year(year) ? DAYS_PER_LEAP_YEAR : DAYS_PER_COMMON_YEAR;
87 }
88
89 #endif /* _SYS_CLOCK_H_ */
90