/* $NetBSD: clock_subr.c,v 1.27 2016/08/15 15:51:39 jakllsch Exp $ */

/* $NetBSD: clock_subr.c,v 1.27 2016/08/15 15:51:39 jakllsch 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
*/

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif /* HAVE_NBTOOL_CONFIG_H */

#ifdef _KERNEL
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: clock_subr.c,v 1.27 2016/08/15 15:51:39 jakllsch Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/errno.h>
#else /* ! _KERNEL */
#include <string.h>
#include <time.h>
#include <errno.h>
#endif /* ! _KERNEL */

#include "../sys/clock.h"
#include <dev/clock_subr.h>

#define FEBRUARY 2

/* for easier alignment:
* time from the epoch to 2001 (there were 8 leap years): */
#define DAYSTO2001 (365*31+8)

/* 4 year intervals include 1 leap year */
#define DAYS4YEARS (365*4+1)

/* 100 year intervals include 24 leap years */
#define DAYS100YEARS (365*100+24)

/* 400 year intervals include 97 leap years */
#define DAYS400YEARS (365*400+97)

time_t
clock_ymdhms_to_secs(struct clock_ymdhms *dt)
{
uint64_t secs, i, year, days;

year = dt->dt_year;

/*
* Compute days since start of time
* First from years, then from months.
*/
if (year < POSIX_BASE_YEAR)
return -1;
days = 0;
if (is_leap_year(year) && dt->dt_mon > FEBRUARY)
days++;

if (year < 2001) {
/* simple way for early years */
for (i = POSIX_BASE_YEAR; i < year; i++)
days += days_per_year(i);
} else {
/* years are properly aligned */
days += DAYSTO2001;
year -= 2001;

i = year / 400;
days += i * DAYS400YEARS;
year -= i * 400;

i = year / 100;
days += i * DAYS100YEARS;
year -= i * 100;

i = year / 4;
days += i * DAYS4YEARS;
year -= i * 4;

for (i = dt->dt_year-year; i < dt->dt_year; i++)
days += days_per_year(i);
}

/* Months */
for (i = 1; i < dt->dt_mon; i++)
days += days_in_month(i);
days += (dt->dt_day - 1);

/* Add hours, minutes, seconds. */
secs = (((uint64_t)days
* 24 + dt->dt_hour)
* 60 + dt->dt_min)
* 60 + dt->dt_sec;

if ((time_t)secs < 0 || secs > __type_max(time_t))
return -1;
return secs;
}

int
clock_secs_to_ymdhms(time_t secs, struct clock_ymdhms *dt)
{
int leap;
uint64_t i;
time_t days;
time_t rsec; /* remainder seconds */

if (secs < 0)
return EINVAL;

days = secs / SECS_PER_DAY;
rsec = secs % SECS_PER_DAY;

/* Day of week (Note: 1/1/1970 was a Thursday) */
dt->dt_wday = (days + 4) % 7;

if (days >= DAYSTO2001) {
days -= DAYSTO2001;
dt->dt_year = 2001;

i = days / DAYS400YEARS;
days -= i*DAYS400YEARS;
dt->dt_year += i*400;

i = days / DAYS100YEARS;
days -= i*DAYS100YEARS;
dt->dt_year += i*100;

i = days / DAYS4YEARS;
days -= i*DAYS4YEARS;
dt->dt_year += i*4;

for (i = dt->dt_year; days >= days_per_year(i); i++)
days -= days_per_year(i);
dt->dt_year = i;
} else {
/* Subtract out whole years, counting them in i. */
for (i = POSIX_BASE_YEAR; days >= days_per_year(i); i++)
days -= days_per_year(i);
dt->dt_year = i;
}

/* Subtract out whole months, counting them in i. */
for (leap = 0, i = 1; days >= days_in_month(i)+leap; i++) {
days -= days_in_month(i)+leap;
if (i == 1 && is_leap_year(dt->dt_year))
leap = 1;
else
leap = 0;
}
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 / SECS_PER_HOUR;
rsec = rsec % SECS_PER_HOUR;
dt->dt_min = rsec / SECS_PER_MINUTE;
rsec = rsec % SECS_PER_MINUTE;
dt->dt_sec = rsec;

return 0;
}