/*      $NetBSD: calyearstart.c,v 1.5 2020/05/25 20:47:24 christos Exp $        */

/*
* calyearstart - determine the NTP time at midnight of January 1 in
*                the year of the given date.
*/
#include <config.h>
#include <sys/types.h>

#include "ntp_types.h"
#include "ntp_calendar.h"
#include "ntp_stdlib.h"
#include "ntp_assert.h"

/*
* Juergen Perlinger, 2010-05-02
*
* Redone in terms of the calendar functions. It's rather simple:
* - expand the NTP time stamp
* - split into days and seconds since midnight, dropping the partial day
* - get full number of days before year start in NTP epoch
* - convert to seconds, truncated to 32 bits.
*/
u_int32
calyearstart(u_int32 ntptime, const time_t *pivot)
{
       u_int32      ndays; /* elapsed days since NTP starts */
       vint64       vlong;
       ntpcal_split split;

       vlong = ntpcal_ntp_to_ntp(ntptime, pivot);
       split = ntpcal_daysplit(&vlong);
       ndays = ntpcal_rd_to_ystart(split.hi + DAY_NTP_STARTS)
             - DAY_NTP_STARTS;

       return (u_int32)(ndays * SECSPERDAY);
}

/*
* calmonthstart - get NTP time at midnight of the first day of the
* current month.
*/
u_int32
calmonthstart(u_int32 ntptime, const time_t *pivot)
{
       u_int32      ndays; /* elapsed days since NTP starts */
       vint64       vlong;
       ntpcal_split split;

       vlong = ntpcal_ntp_to_ntp(ntptime, pivot);
       split = ntpcal_daysplit(&vlong);
       ndays = ntpcal_rd_to_mstart(split.hi + DAY_NTP_STARTS)
             - DAY_NTP_STARTS;

       return (u_int32)(ndays * SECSPERDAY);
}

/*
* calweekstart - get NTP time at midnight of the last Monday on or
* before the current date.
*/
u_int32
calweekstart(u_int32 ntptime, const time_t *pivot)
{
       u_int32      ndays; /* elapsed days since NTP starts */
       vint64       vlong;
       ntpcal_split split;

       vlong = ntpcal_ntp_to_ntp(ntptime, pivot);
       split = ntpcal_daysplit(&vlong);
       ndays = ntpcal_weekday_le(split.hi + DAY_NTP_STARTS, CAL_MONDAY)
             - DAY_NTP_STARTS;

       return (u_int32)(ndays * SECSPERDAY);
}

/*
* caldaystart - get NTP time at midnight of the current day.
*/
u_int32
caldaystart(u_int32 ntptime, const time_t *pivot)
{
       vint64       vlong;
       ntpcal_split split;

       vlong = ntpcal_ntp_to_ntp(ntptime, pivot);
       split = ntpcal_daysplit(&vlong);

       return ntptime - split.lo;
}