2 * caljulian - determine the Julian date from an NTP time.
7 #include "ntp_calendar.h"
8 #include "ntp_stdlib.h"
13 * calmonthtab - days-in-the-month table
15 static u_short calmonthtab[11] = {
32 register struct calendar *jt
38 * Absolute, zero-adjusted Christian era day, starting from the
39 * mythical day 12/1/1 BC
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 */
53 * Do the easy stuff first: take care of hh:mm:ss, ignoring leap
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);
62 * Find the day past 1900/01/01 00:00 UTC
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;
75 * Calculate the year and year-of-day
77 jt->yearday = (u_short)(1 + d4%DAYSPERYEAR);
78 jt->year = (u_short)(400*n400 + 100*n100 + n4*4 + n1);
80 if (n100 == 4 || n1 == 4)
83 * If the cycle year ever comes out to 4, it must be December 31st
93 * Else, search forwards through the months to get the right month
99 monthday = jt->yearday;
101 for (jt->month=0;jt->month<11; jt->month++)
105 t = monthday - calmonthtab[jt->month];
106 if (jt->month == 1 && is_leapyear(jt->year))
115 jt->monthday = (u_char) monthday;
120 /* Updated 2003-12-30 TMa
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.
131 register struct calendar *jt
136 tm = ntp2unix_tm(ntptime, 0);
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! */