source: buchla-68k/orig/DATE/TODAY.C

/*
   =============================================================================
        today.c -- print the date and time of day
        Version 1 -- 1988-12-05 -- D.N. Lynx Crowe
   =============================================================================
*/

#include "osbind.h"
#include "stddefs.h"

char    *days[] = {

        "Sunday",
        "Monday",
        "Tuesday",
        "Wednesday",
        "Thursday",
        "Friday",
        "Saturday"
};

char    *mons[] = {

        "January",
        "February",
        "March",
        "April",
        "May",
        "June",
        "July",
        "August",
        "September",
        "October",
        "November",
        "December"
};

/* 

*/

/*
   =============================================================================
        wkday() -- determine the day of the week by Zeller's Congruence

        Uses the Gregorian calendar -- accurate from 1752 through 4901 A.D.

        short
        wkday(year, month, day)
        short year, month, day;

                year    1752..4901
                month   1..12           1 = Jan., 2 = Feb., ..., 12 = Dec.
                day     1..31

        Returns:

                0 - Sunday
                1 - Monday
                2 - Tuesday
                3 - Wednesday
                4 - Thursday
                5 - Friday
                6 - Saturday
   =============================================================================
*/

short
wkday(year, month, day)
register short year, month, day;
{
        register short cen, yinc;

        month -= 2;

        if (month < 1) {

                month += 12;
                --year;
        }

        cen = year / 100;
        yinc = year - (cen * 100);

        return(((((26 * month) - 2) / 10) + day + yinc + (yinc / 4)
                + (cen / 4) - (2 * cen)) % 7);
}

/* 

*/

main()
{
        register long t;
        short yr, mn, dy, hh, mm, ss;

        t = Gettime();

        yr = ((short)(t >> 25) & 0x007F) + 1980;
        mn =  (short)(t >> 21) & 0x000F;
        dy =  (short)(t >> 16) & 0x001F;

        hh = (short)(t >> 11) & 0x001F;
        mm = (short)(t >>  5) & 0x003F;
        ss = ((short)t & 0x001F) << 1;

        printf("It is %02d:%02d:%02d on %s,  %s %d, %d.\n",
                hh, mm, ss,
                days[wkday(yr, mn, dy)],
                mons[mn - 1], dy, yr);

        exit(0);
}