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/* $OpenBSD: clock_subr.c,v 1.6 2016/08/26 07:09:56 guenther Exp $ */
/* $NetBSD: clock_subr.c,v 1.3 1997/03/15 18:11:16 is Exp $ */
/*
* Copyright (c) 1988 University of Utah.
* Copyright (c) 1982, 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: Utah $Hdr: clock.c 1.18 91/01/21$
*
* @(#)clock.c 8.2 (Berkeley) 1/12/94
*/
/*
* Generic routines to convert between a POSIX date
* (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
* Derived from arch/hp300/hp300/clock.c
*/
#include <sys/types.h>
#include <sys/time.h>
#include <sys/systm.h>
static inline int leapyear(int year);
#define FEBRUARY 2
#define days_in_year(a) (leapyear(a) ? 366 : 365)
#define days_in_month(a) (month_days[(a) - 1])
static const int month_days[12] = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
/*
* This inline avoids some unnecessary modulo operations
* as compared with the usual macro:
* ( ((year % 4) == 0 &&
* (year % 100) != 0) ||
* ((year % 400) == 0) )
* It is otherwise equivalent.
*/
static inline int
leapyear(int year)
{
int rv = 0;
if ((year & 3) == 0) {
rv = 1;
if ((year % 100) == 0) {
rv = 0;
if ((year % 400) == 0)
rv = 1;
}
}
return (rv);
}
time_t
clock_ymdhms_to_secs(struct clock_ymdhms *dt)
{
time_t secs;
int i, year, days;
year = dt->dt_year;
/*
* Compute days since start of time.
* First from years, then from months.
*/
days = 0;
for (i = POSIX_BASE_YEAR; i < year; i++)
days += days_in_year(i);
if (leapyear(year) && dt->dt_mon > FEBRUARY)
days++;
/* Months */
for (i = 1; i < dt->dt_mon; i++)
days += days_in_month(i);
days += (dt->dt_day - 1);
/* Add hours, minutes, seconds. */
secs = (time_t)((days
* 24 + dt->dt_hour)
* 60 + dt->dt_min)
* 60 + dt->dt_sec;
return (secs);
}
/* This function uses a copy of month_days[] */
#undef days_in_month
#define days_in_month(a) (mthdays[(a) - 1])
void
clock_secs_to_ymdhms(time_t secs, struct clock_ymdhms *dt)
{
int mthdays[12];
int i, days;
int rsec; /* remainder seconds */
memcpy(mthdays, month_days, sizeof(mthdays));
days = secs / SECDAY;
rsec = secs % SECDAY;
/* Day of week (Note: 1/1/1970 was a Thursday) */
dt->dt_wday = (days + 4) % 7;
/* Subtract out whole years, counting them in i. */
for (i = POSIX_BASE_YEAR; days >= days_in_year(i); i++)
days -= days_in_year(i);
dt->dt_year = i;
/* Subtract out whole months, counting them in i. */
if (leapyear(i))
days_in_month(FEBRUARY) = 29;
for (i = 1; days >= days_in_month(i); i++)
days -= days_in_month(i);
dt->dt_mon = i;
/* Days are what is left over (+1) from all that. */
dt->dt_day = days + 1;
/* Hours, minutes, seconds are easy */
dt->dt_hour = rsec / 3600;
rsec = rsec % 3600;
dt->dt_min = rsec / 60;
rsec = rsec % 60;
dt->dt_sec = rsec;
}
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