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