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Annotation of coherent/g/usr/lib/misc/tmtojd.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Year, month, day to julian day in integers.
                      3:  * Algorithm from Duffett-Smith, Practical Astronomy With Your Calculator
                      4:  * Also Meeus, Astronomical Formulae for Calculators
                      5:  */
                      6: #include "local_misc.h"
                      7: 
                      8: /* Pack year, month, and day into long package for easy compares */
                      9: #define pymd(y,m,d)    (((long)(y)<<16)|((m)<<8)|(d))
                     10: 
                     11: jday_t
                     12: tm_to_jday(tp)
                     13: register tm_t *tp;
                     14: {
                     15:        register int y, m, B;
                     16:        register long C, D;
                     17:        jday_t jd;
                     18: 
                     19:        y = tp->tm_year + 1900;
                     20:        m = tp->tm_mon + 1;
                     21:        if (m <= 2) {
                     22:                y -= 1; m += 12;
                     23:        }
                     24:        /* Gregorian correction */
                     25:        if (pymd(y, m, tp->tm_mday) > pymd(1582, 10, 15)) {
                     26:                B = 2 - (y/100) + (y/400);
                     27:        } else
                     28:                B = 0;
                     29:        C = (y * 36525L) / 100;
                     30:        D = ((m + 1) * 306001L) / 10000;
                     31:        jd.j_d = tp->tm_mday + B + C + D + 1720994L;
                     32:        jd.j_s = tp->tm_sec + 60L * (tp->tm_min + 60 * tp->tm_hour);
                     33:        if ((jd.j_s += 86400L/2) >= 86400L) {
                     34:                jd.j_s -= 86400L; jd.j_d += 1;
                     35:        }
                     36:        return jd;
                     37: }

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