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Diffstat (limited to 'contrib/ntp/include/ntp_calendar.h')
-rw-r--r-- | contrib/ntp/include/ntp_calendar.h | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/contrib/ntp/include/ntp_calendar.h b/contrib/ntp/include/ntp_calendar.h new file mode 100644 index 0000000..95e2c12 --- /dev/null +++ b/contrib/ntp/include/ntp_calendar.h @@ -0,0 +1,112 @@ +/* + * ntp_calendar.h - definitions for the calendar time-of-day routine + */ +#ifndef NTP_CALENDAR_H +#define NTP_CALENDAR_H + +#include "ntp_types.h" + +struct calendar { + u_short year; /* year (A.D.) */ + u_short yearday; /* day of year, 1 = January 1 */ + u_char month; /* month, 1 = January */ + u_char monthday; /* day of month */ + u_char hour; /* hour of day, midnight = 0 */ + u_char minute; /* minute of hour */ + u_char second; /* second of minute */ +}; + +/* + * Days in each month. 30 days hath September... + */ +#define JAN 31 +#define FEB 28 +#define FEBLEAP 29 +#define MAR 31 +#define APR 30 +#define MAY 31 +#define JUN 30 +#define JUL 31 +#define AUG 31 +#define SEP 30 +#define OCT 31 +#define NOV 30 +#define DEC 31 + +/* + * We deal in a 4 year cycle starting at March 1, 1900. We assume + * we will only want to deal with dates since then, and not to exceed + * the rollover day in 2036. + */ +#define SECSPERMIN (60) /* seconds per minute */ +#define MINSPERHR (60) /* minutes per hour */ +#define HRSPERDAY (24) /* hours per day */ +#define DAYSPERYEAR (365) /* days per year */ + +#define SECSPERDAY (SECSPERMIN*MINSPERHR*HRSPERDAY) +#define SECSPERYEAR (365 * SECSPERDAY) /* regular year */ +#define SECSPERLEAPYEAR (366 * SECSPERDAY) /* leap year */ + +#define MAR1900 ((JAN+FEB) * SECSPERDAY) /* no leap year in 1900 */ +#define DAYSPERCYCLE (365+365+365+366) /* 3 normal years plus leap */ +#define SECSPERCYCLE (DAYSPERCYCLE*SECSPERDAY) +#define YEARSPERCYCLE 4 + +/* + * Gross hacks. I have illicit knowlege that there won't be overflows + * here, the compiler often can't tell this. + */ +#define TIMES60(val) ((((val)<<4) - (val))<<2) /* *(16 - 1) * 4 */ +#define TIMES24(val) (((val)<<4) + ((val)<<3)) /* *16 + *8 */ +#define TIMES7(val) (((val)<<3) - (val)) /* *8 - *1 */ +#define TIMESDPERC(val) (((val)<<10) + ((val)<<8) \ + + ((val)<<7) + ((val)<<5) \ + + ((val)<<4) + ((val)<<2) + (val)) /* *big* hack */ + +/* + * Another big hack. Cycle 22 started on March 1, 1988. This is + * STARTCYCLE22 seconds after the start of cycle 0. + */ +#define CYCLE22 (22) +#define STARTCYCLE22 (u_long)(0xa586b500) /* 2777068800 */ +#define MAR1988 (u_long)(STARTCYCLE22 + (u_long)MAR1900) + +/* + * The length of January + February in leap and non-leap years. + */ +#define JANFEBNOLEAP ((JAN+FEB) * SECSPERDAY) +#define JANFEBLEAP ((JAN+FEBLEAP) * SECSPERDAY) + + +extern void caljulian P((u_long, struct calendar *)); +extern u_long caltontp P((const struct calendar *)); + +/* + * Additional support stuff for Ed Rheingold's calendrical calculations + */ + +/* + * Start day of NTP time as days past the imaginary date 12/1/1 BC. + * P((This is the beginning of the Christian Era, or BCE.)) + */ +#define DAY_NTP_STARTS 693596 +/* + * The Gregorian calendar is based on a 400 year cycle. This is the number + * of days in each cycle. + */ +#define GREGORIAN_CYCLE_DAYS 146097 + +/* + * Days in a normal 100 year leap year calendar. We lose a leap year day + * in years evenly divisible by 100 but not by 400. + */ +#define GREGORIAN_NORMAL_CENTURY_DAYS 36524 + +/* + * Days in a normal 4 year leap year calendar cycle. + */ +#define GREGORIAN_NORMAL_LEAP_CYCLE_DAYS 1461 + +#define is_leapyear(y) (y%4 == 0 && !(y%100 == 0 && !(y%400 == 0))) + +#endif |