/contrib/ntp/libntp/caljulian.c

  1/*
  2 * caljulian - determine the Julian date from an NTP time.
  3 */
  4#include <sys/types.h>
  5
  6#include "ntp_types.h"
  7#include "ntp_calendar.h"
  8#include "ntp_stdlib.h"
  9#include "ntp_fp.h"
 10
 11#if 0
 12/*
 13 * calmonthtab - days-in-the-month table
 14 */
 15static u_short calmonthtab[11] = {
 16	JAN,
 17	FEB,
 18	MAR,
 19	APR,
 20	MAY,
 21	JUN,
 22	JUL,
 23	AUG,
 24	SEP,
 25	OCT,
 26	NOV
 27};
 28
 29void
 30caljulian(
 31	u_long		  		ntptime,
 32	register struct calendar	*jt
 33	)
 34{
 35	u_long ntp_day;
 36	u_long minutes;
 37	/*
 38	 * Absolute, zero-adjusted Christian era day, starting from the
 39	 * mythical day 12/1/1 BC
 40	 */
 41	u_long acez_day;
 42
 43	u_long d400;				 /* Days into a Gregorian cycle */
 44	u_long d100;				 /* Days into a normal century */
 45	u_long d4;					 /* Days into a 4-year cycle */
 46	u_long n400;				 /* # of Gregorian cycles */
 47	u_long n100;				 /* # of normal centuries */
 48	u_long n4;					 /* # of 4-year cycles */
 49	u_long n1;					 /* # of years into a leap year */
 50						 /*   cycle */
 51
 52	/*
 53	 * Do the easy stuff first: take care of hh:mm:ss, ignoring leap
 54	 * seconds
 55	 */
 56	jt->second = (u_char)(ntptime % SECSPERMIN);
 57	minutes    = ntptime / SECSPERMIN;
 58	jt->minute = (u_char)(minutes % MINSPERHR);
 59	jt->hour   = (u_char)((minutes / MINSPERHR) % HRSPERDAY);
 60
 61	/*
 62	 * Find the day past 1900/01/01 00:00 UTC
 63	 */
 64	ntp_day = ntptime / SECSPERDAY;
 65	acez_day = DAY_NTP_STARTS + ntp_day - 1;
 66	n400	 = acez_day/GREGORIAN_CYCLE_DAYS;
 67	d400	 = acez_day%GREGORIAN_CYCLE_DAYS;
 68	n100	 = d400 / GREGORIAN_NORMAL_CENTURY_DAYS;
 69	d100	 = d400 % GREGORIAN_NORMAL_CENTURY_DAYS;
 70	n4		 = d100 / GREGORIAN_NORMAL_LEAP_CYCLE_DAYS;
 71	d4		 = d100 % GREGORIAN_NORMAL_LEAP_CYCLE_DAYS;
 72	n1		 = d4 / DAYSPERYEAR;
 73
 74	/*
 75	 * Calculate the year and year-of-day
 76	 */
 77	jt->yearday = (u_short)(1 + d4%DAYSPERYEAR);
 78	jt->year	= (u_short)(400*n400 + 100*n100 + n4*4 + n1);
 79
 80	if (n100 == 4 || n1 == 4)
 81	{
 82	/*
 83	 * If the cycle year ever comes out to 4, it must be December 31st
 84	 * of a leap year.
 85	 */
 86	jt->month	 = 12;
 87	jt->monthday = 31;
 88	jt->yearday  = 366;
 89	}
 90	else
 91	{
 92	/*
 93	 * Else, search forwards through the months to get the right month
 94	 * and date.
 95	 */
 96	int monthday;
 97
 98	jt->year++;
 99	monthday = jt->yearday;
100
101	for (jt->month=0;jt->month<11; jt->month++)
102	{
103		int t;
104
105		t = monthday - calmonthtab[jt->month];
106		if (jt->month == 1 && is_leapyear(jt->year))
107		t--;
108
109		if (t > 0)
110		monthday = t;
111		else
112		break;
113	}
114	jt->month++;
115	jt->monthday = (u_char) monthday;
116	}
117}
118#else
119
120/* Updated 2003-12-30 TMa
121
122   Uses common code with the *prettydate functions to convert an ntp
123   seconds count into a calendar date.
124   Will handle ntp epoch wraparound as long as the underlying os/library 
125   does so for the unix epoch, i.e. works after 2038.
126*/
127
128void
129caljulian(
130	u_long		  		ntptime,
131	register struct calendar	*jt
132	)
133{
134	struct tm *tm;
135
136	tm = ntp2unix_tm(ntptime, 0);
137
138	jt->hour = (u_char) tm->tm_hour;
139	jt->minute = (u_char) tm->tm_min;
140	jt->month = (u_char) (tm->tm_mon + 1);
141	jt->monthday = (u_char) tm->tm_mday;
142	jt->second = (u_char) tm->tm_sec;
143	jt->year = (u_short) (tm->tm_year + 1900);
144	jt->yearday = (u_short) (tm->tm_yday + 1);  /* Assumes tm_yday starts with day 0! */
145}
146#endif