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Annotation of embedaddon/ntp/include/ntp_calendar.h, revision 1.1

1.1     ! misho       1: /*
        !             2:  * ntp_calendar.h - definitions for the calendar time-of-day routine
        !             3:  */
        !             4: #ifndef NTP_CALENDAR_H
        !             5: #define NTP_CALENDAR_H
        !             6: 
        !             7: #include "ntp_types.h"
        !             8: 
        !             9: struct calendar {
        !            10:        u_short year;           /* year (A.D.) */
        !            11:        u_short yearday;        /* day of year, 1 = January 1 */
        !            12:        u_char month;           /* month, 1 = January */
        !            13:        u_char monthday;        /* day of month */
        !            14:        u_char hour;            /* hour of day, midnight = 0 */
        !            15:        u_char minute;          /* minute of hour */
        !            16:        u_char second;          /* second of minute */
        !            17: };
        !            18: 
        !            19: /*
        !            20:  * Days in each month.  30 days hath September...
        !            21:  */
        !            22: #define        JAN     31
        !            23: #define        FEB     28
        !            24: #define        FEBLEAP 29
        !            25: #define        MAR     31
        !            26: #define        APR     30
        !            27: #define        MAY     31
        !            28: #define        JUN     30
        !            29: #define        JUL     31
        !            30: #define        AUG     31
        !            31: #define        SEP     30
        !            32: #define        OCT     31
        !            33: #define        NOV     30
        !            34: #define        DEC     31
        !            35: 
        !            36: /*
        !            37:  * We deal in a 4 year cycle starting at March 1, 1900.  We assume
        !            38:  * we will only want to deal with dates since then, and not to exceed
        !            39:  * the rollover day in 2036.
        !            40:  */
        !            41: #define        SECSPERMIN      (60)                    /* seconds per minute */
        !            42: #define        MINSPERHR       (60)                    /* minutes per hour */
        !            43: #define        HRSPERDAY       (24)                    /* hours per day */
        !            44: #define        DAYSPERYEAR     (365)                   /* days per year */
        !            45: 
        !            46: #define        SECSPERDAY      (SECSPERMIN*MINSPERHR*HRSPERDAY)
        !            47: #define        SECSPERYEAR     (365 * SECSPERDAY)      /* regular year */
        !            48: #define        SECSPERLEAPYEAR (366 * SECSPERDAY)      /* leap year */
        !            49: 
        !            50: #define        MAR1900         ((JAN+FEB) * SECSPERDAY) /* no leap year in 1900 */
        !            51: #define        DAYSPERCYCLE    (365+365+365+366)       /* 3 normal years plus leap */
        !            52: #define        SECSPERCYCLE    (DAYSPERCYCLE*SECSPERDAY)
        !            53: #define        YEARSPERCYCLE   4
        !            54: 
        !            55: /*
        !            56:  * Gross hacks.  I have illicit knowlege that there won't be overflows
        !            57:  * here, the compiler often can't tell this.
        !            58:  */
        !            59: #define        TIMES60(val)    ((((val)<<4) - (val))<<2)       /* *(16 - 1) * 4 */
        !            60: #define        TIMES24(val)    (((val)<<4) + ((val)<<3))       /* *16 + *8 */
        !            61: #define        TIMES7(val)     (((val)<<3) - (val))            /* *8  - *1 */
        !            62: #define        TIMESDPERC(val) (((val)<<10) + ((val)<<8) \
        !            63:                        + ((val)<<7) + ((val)<<5) \
        !            64:                        + ((val)<<4) + ((val)<<2) + (val))      /* *big* hack */
        !            65: 
        !            66: /*
        !            67:  * Another big hack.  Cycle 22 started on March 1, 1988.  This is
        !            68:  * STARTCYCLE22 seconds after the start of cycle 0.
        !            69:  */
        !            70: #define        CYCLE22         (22)
        !            71: #define        STARTCYCLE22    (u_long)(0xa586b500)    /* 2777068800 */
        !            72: #define        MAR1988         (u_long)(STARTCYCLE22 + (u_long)MAR1900)
        !            73: 
        !            74: /*
        !            75:  * The length of January + February in leap and non-leap years.
        !            76:  */
        !            77: #define        JANFEBNOLEAP    ((JAN+FEB) * SECSPERDAY)
        !            78: #define        JANFEBLEAP      ((JAN+FEBLEAP) * SECSPERDAY)
        !            79: 
        !            80: 
        !            81: extern void    caljulian       (u_long, struct calendar *);
        !            82: extern u_long  caltontp        (const struct calendar *);
        !            83: 
        !            84: /*
        !            85:  * Additional support stuff for Ed Rheingold's calendrical calculations
        !            86:  */
        !            87: 
        !            88: /*
        !            89:  * Start day of NTP time as days past the imaginary date 12/1/1 BC.
        !            90:  * (This is the beginning of the Christian Era, or BCE.)
        !            91:  */
        !            92: #define        DAY_NTP_STARTS 693596
        !            93: /*
        !            94:  * The Gregorian calendar is based on a 400 year cycle.  This is the number
        !            95:  * of days in each cycle.
        !            96:  */
        !            97: #define        GREGORIAN_CYCLE_DAYS 146097
        !            98: 
        !            99: /*
        !           100:  * Days in a normal 100 year leap year calendar.  We lose a leap year day
        !           101:  * in years evenly divisible by 100 but not by 400.
        !           102:  */
        !           103: #define        GREGORIAN_NORMAL_CENTURY_DAYS 36524
        !           104: 
        !           105: /*
        !           106:  * Days in a normal 4 year leap year calendar cycle.
        !           107:  */
        !           108: #define        GREGORIAN_NORMAL_LEAP_CYCLE_DAYS 1461
        !           109: 
        !           110: #define        is_leapyear(y)  (!((y) % 4) && !(!((y) % 100) && (y) % 400))
        !           111: 
        !           112: #endif