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      1 /*	$NetBSD: clock.h,v 1.7 2023/10/27 14:34:58 jschauma 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 #if !defined(_KERNEL) && !defined(_STANDALONE)
     36 #include <stdint.h>
     37 #endif
     38 
     39 /* Some handy constants. */
     40 #define SECS_PER_MINUTE		60
     41 #define SECS_PER_HOUR		3600
     42 #define SECS_PER_DAY		86400
     43 #define DAYS_PER_COMMON_YEAR    365
     44 #define DAYS_PER_LEAP_YEAR      366
     45 #define SECS_PER_COMMON_YEAR	(SECS_PER_DAY * DAYS_PER_COMMON_YEAR)
     46 #define SECS_PER_LEAP_YEAR	(SECS_PER_DAY * DAYS_PER_LEAP_YEAR)
     47 
     48 /* Traditional POSIX base year */
     49 #define	POSIX_BASE_YEAR	1970
     50 
     51 /* Some handy functions */
     52 static __inline int
     53 days_in_month(int m)
     54 {
     55 	switch (m) {
     56 	case 2:
     57 		return 28;
     58 	case 4: case 6: case 9: case 11:
     59 		return 30;
     60 	case 1: case 3: case 5: case 7: case 8: case 10: case 12:
     61 		return 31;
     62 	default:
     63 		return -1;
     64 	}
     65 }
     66 
     67 /*
     68  * This inline avoids some unnecessary modulo operations
     69  * as compared with the usual macro:
     70  *   ( ((year % 4) == 0 &&
     71  *      (year % 100) != 0) ||
     72  *     ((year % 400) == 0) )
     73  * It is otherwise equivalent.
     74  */
     75 static __inline int
     76 is_leap_year(uint64_t year)
     77 {
     78 	if ((year & 3) != 0)
     79 		return 0;
     80 
     81 	if (__predict_false((year % 100) != 0))
     82 		return 1;
     83 
     84 	return __predict_false((year % 400) == 0);
     85 }
     86 
     87 static __inline int
     88 days_per_year(uint64_t year)
     89 {
     90 	return is_leap_year(year) ? DAYS_PER_LEAP_YEAR : DAYS_PER_COMMON_YEAR;
     91 }
     92 
     93 #endif /* _SYS_CLOCK_H_ */
     94