/contrib/ntp/include/ntp_calendar.h

  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
  9struct 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
 81extern	void	caljulian	P((u_long, struct calendar *));
 82extern	u_long	caltontp	P((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 * P((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 == 0 && !(y%100 == 0 && !(y%400 == 0)))
111
112#endif