ntp_calendar.h revision 290001 
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 <time.h>
8
9#include "ntp_types.h"
10
11/* gregorian calendar date */
12struct calendar {
13	uint16_t year;		/* year (A.D.) */
14	uint16_t yearday;	/* day of year, 1 = January 1 */
15	uint8_t  month;		/* month, 1 = January */
16	uint8_t  monthday;	/* day of month */
17	uint8_t  hour;		/* hour of day, midnight = 0 */
18	uint8_t  minute;	/* minute of hour */
19	uint8_t  second;	/* second of minute */
20	uint8_t  weekday;	/* 0..7, 0=Sunday */
21};
22
23/* ISO week calendar date */
24struct isodate {
25	uint16_t year;		/* year (A.D.) */
26	uint8_t	 week;		/* 1..53, week in year */
27	uint8_t	 weekday;	/* 1..7, 1=Monday */
28	uint8_t	 hour;		/* hour of day, midnight = 0 */
29	uint8_t	 minute;	/* minute of hour */
30	uint8_t	 second;	/* second of minute */
31};
32
33/* general split representation */
34typedef struct {
35	int32_t hi;
36	int32_t lo;
37} ntpcal_split;
38
39typedef time_t (*systime_func_ptr)(time_t *);
40
41/*
42 * set the function for getting the system time. This is mostly used for
43 * unit testing to provide a fixed / shifted time stamp. Setting the
44 * value to NULL restores the original function, that is, 'time()',
45 * which is also the automatic default.
46 */
47extern systime_func_ptr ntpcal_set_timefunc(systime_func_ptr);
48
49/*
50 * days-of-week
51 */
52#define CAL_SUNDAY	0
53#define CAL_MONDAY	1
54#define CAL_TUESDAY	2
55#define CAL_WEDNESDAY	3
56#define CAL_THURSDAY	4
57#define CAL_FRIDAY	5
58#define CAL_SATURDAY	6
59#define CAL_SUNDAY7	7	/* also sunday */
60
61/*
62 * Days in each month.	30 days hath September...
63 */
64#define	JAN	31
65#define	FEB	28
66#define	FEBLEAP	29
67#define	MAR	31
68#define	APR	30
69#define	MAY	31
70#define	JUN	30
71#define	JUL	31
72#define	AUG	31
73#define	SEP	30
74#define	OCT	31
75#define	NOV	30
76#define	DEC	31
77
78/*
79 * We deal in a 4 year cycle starting at March 1, 1900.	 We assume
80 * we will only want to deal with dates since then, and not to exceed
81 * the rollover day in 2036.
82 */
83#define	SECSPERMIN	(60)			/* seconds per minute */
84#define	MINSPERHR	(60)			/* minutes per hour */
85#define	HRSPERDAY	(24)			/* hours per day */
86#define	DAYSPERWEEK	(7)			/* days per week */
87#define	DAYSPERYEAR	(365)			/* days per year */
88
89#define	SECSPERHR	(SECSPERMIN * MINSPERHR)
90#define	SECSPERDAY	(SECSPERHR * HRSPERDAY)
91#define	SECSPERWEEK	(DAYSPERWEEK * SECSPERDAY)
92#define	SECSPERYEAR	(365 * SECSPERDAY)	/* regular year */
93#define	SECSPERLEAPYEAR	(366 * SECSPERDAY)	/* leap year */
94#define	SECSPERAVGYEAR	31556952		/* mean year length over 400yrs */
95
96/*
97 * Gross hacks.	 I have illicit knowlege that there won't be overflows
98 * here, the compiler often can't tell this.
99 */
100#define	TIMES60(val)	((((val)<<4) - (val))<<2)	/* *(16 - 1) * 4 */
101#define	TIMES24(val)	(((val)<<4) + ((val)<<3))	/* *16 + *8 */
102#define	TIMES7(val)	(((val)<<3) - (val))		/* *8  - *1 */
103#define	TIMESDPERC(val)	(((val)<<10) + ((val)<<8) \
104			+ ((val)<<7) + ((val)<<5) \
105			+ ((val)<<4) + ((val)<<2) + (val))	/* *big* hack */
106
107
108extern	const char * const months[12];
109extern	const char * const daynames[7];
110
111extern	void	 caljulian	(uint32_t, struct calendar *);
112extern	uint32_t caltontp	(const struct calendar *);
113
114/*
115 * Convert between 'time_t' and 'vint64'
116 */
117extern vint64 time_to_vint64(const time_t *);
118extern time_t vint64_to_time(const vint64 *);
119
120/*
121 * Get the build date & time. ATTENTION: The time zone is not specified!
122 * This depends entirely on the C compilers' capabilities to properly
123 * expand the '__TIME__' and '__DATE__' macros, as required by the C
124 * standard.
125 */
126extern int
127ntpcal_get_build_date(struct calendar * /* jd */);
128
129/*
130 * Convert a timestamp in NTP scale to a time_t value in the UN*X
131 * scale with proper epoch unfolding around a given pivot or the
132 * current system time.
133 */
134extern vint64
135ntpcal_ntp_to_time(uint32_t /* ntp */, const time_t * /* pivot */);
136
137/*
138 * Convert a timestamp in NTP scale to a 64bit seconds value in the NTP
139 * scale with proper epoch unfolding around a given pivot or the current
140 * system time.
141 * Note: The pivot must be given in UN*X time scale!
142 */
143extern vint64
144ntpcal_ntp_to_ntp(uint32_t /* ntp */, const time_t * /* pivot */);
145
146/*
147 * Split a time stamp in seconds into elapsed days and elapsed seconds
148 * since midnight.
149 */
150extern ntpcal_split
151ntpcal_daysplit(const vint64 *);
152
153/*
154 * Merge a number of days and a number of seconds into seconds,
155 * expressed in 64 bits to avoid overflow.
156 */
157extern vint64
158ntpcal_dayjoin(int32_t /* days */, int32_t /* seconds */);
159
160/* Get the number of leap years since epoch for the number of elapsed
161 * full years
162 */
163extern int32_t
164ntpcal_leapyears_in_years(int32_t /* years */);
165
166/*
167 * Convert elapsed years in Era into elapsed days in Era.
168 */
169extern int32_t
170ntpcal_days_in_years(int32_t /* years */);
171
172/*
173 * Convert a number of elapsed month in a year into elapsed days
174 * in year.
175 *
176 * The month will be normalized, and 'res.hi' will contain the
177 * excessive years that must be considered when converting the years,
178 * while 'res.lo' will contain the days since start of the
179 * year. (Expect the resulting days to be negative, with a positive
180 * excess! But then, we need no leap year flag, either...)
181 */
182extern ntpcal_split
183ntpcal_days_in_months(int32_t /* months */);
184
185/*
186 * Convert ELAPSED years/months/days of gregorian calendar to elapsed
187 * days in Gregorian epoch. No range checks done here!
188 */
189extern int32_t
190ntpcal_edate_to_eradays(int32_t /* years */, int32_t /* months */, int32_t /* mdays */);
191
192/*
193 * Convert a time spec to seconds. No range checks done here!
194 */
195extern int32_t
196ntpcal_etime_to_seconds(int32_t /* hours */, int32_t /* minutes */, int32_t /* seconds */);
197
198/*
199 * Convert ELAPSED years/months/days of gregorian calendar to elapsed
200 * days in year.
201 *
202 * Note: This will give the true difference to the start of the given year,
203 * even if months & days are off-scale.
204 */
205extern int32_t
206ntpcal_edate_to_yeardays(int32_t /* years */, int32_t /* months */, int32_t /* mdays */);
207
208/*
209 * Convert the date part of a 'struct tm' (that is, year, month,
210 * day-of-month) into the RataDie of that day.
211 */
212extern int32_t
213ntpcal_tm_to_rd(const struct tm * /* utm */);
214
215/*
216 * Convert the date part of a 'struct calendar' (that is, year, month,
217 * day-of-month) into the RataDie of that day.
218 */
219extern int32_t
220ntpcal_date_to_rd(const struct calendar * /* jt */);
221
222/*
223 * Given the number of elapsed days in the calendar era, split this
224 * number into the number of elapsed years in 'res.quot' and the
225 * number of elapsed days of that year in 'res.rem'.
226 *
227 * if 'isleapyear' is not NULL, it will receive an integer that is 0
228 * for regular years and a non-zero value for leap years.
229 *
230 * The input is limited to [-2^30, 2^30-1]. If the days exceed this
231 * range, errno is set to EDOM and the result is saturated.
232 */
233extern ntpcal_split
234ntpcal_split_eradays(int32_t /* days */, int/*BOOL*/ * /* isleapyear */);
235
236/*
237 * Given a number of elapsed days in a year and a leap year indicator,
238 * split the number of elapsed days into the number of elapsed months
239 * in 'res.quot' and the number of elapsed days of that month in
240 * 'res.rem'.
241 */
242extern ntpcal_split
243ntpcal_split_yeardays(int32_t /* eyd */, int/*BOOL*/ /* isleapyear */);
244
245/*
246 * Convert a RataDie number into the date part of a 'struct
247 * calendar'. Return 0 if the year is regular year, !0 if the year is
248 * a leap year.
249 */
250extern int/*BOOL*/
251ntpcal_rd_to_date(struct calendar * /* jt */, int32_t /* rd */);
252
253/*
254 * Convert a RataDie number into the date part of a 'struct
255 * tm'. Return 0 if the year is regular year, !0 if the year is a leap
256 * year.
257 */
258extern int/*BOOL*/
259ntpcal_rd_to_tm(struct tm * /* utm */, int32_t /* rd */);
260
261/*
262 * Take a value of seconds since midnight and split it into hhmmss in
263 * a 'struct calendar'. Return excessive days.
264 */
265extern int32_t
266ntpcal_daysec_to_date(struct calendar * /* jt */, int32_t /* secs */);
267
268/*
269 * Take the time part of a 'struct calendar' and return the seconds
270 * since midnight.
271 */
272extern int32_t
273ntpcal_date_to_daysec(const struct calendar *);
274
275/*
276 * Take a value of seconds since midnight and split it into hhmmss in
277 * a 'struct tm'. Return excessive days.
278 */
279extern int32_t
280ntpcal_daysec_to_tm(struct tm * /* utm */, int32_t /* secs */);
281
282extern int32_t
283ntpcal_tm_to_daysec(const struct tm * /* utm */);
284
285/*
286 * convert a year number to rata die of year start
287 */
288extern int32_t
289ntpcal_year_to_ystart(int32_t /* year */);
290
291/*
292 * For a given RataDie, get the RataDie of the associated year start,
293 * that is, the RataDie of the last January,1st on or before that day.
294 */
295extern int32_t
296ntpcal_rd_to_ystart(int32_t /* rd */);
297
298/*
299 * convert a RataDie to the RataDie of start of the calendar month.
300 */
301extern int32_t
302ntpcal_rd_to_mstart(int32_t /* year */);
303
304
305extern int
306ntpcal_daysplit_to_date(struct calendar * /* jt */,
307			const ntpcal_split * /* ds */, int32_t /* dof */);
308
309extern int
310ntpcal_daysplit_to_tm(struct tm * /* utm */, const ntpcal_split * /* ds */,
311		      int32_t /* dof */);
312
313extern int
314ntpcal_time_to_date(struct calendar * /* jd */, const vint64 * /* ts */);
315
316extern int32_t
317ntpcal_periodic_extend(int32_t /* pivot */, int32_t /* value */,
318		       int32_t /* cycle */);
319
320extern int
321ntpcal_ntp64_to_date(struct calendar * /* jd */, const vint64 * /* ntp */);
322
323extern int
324ntpcal_ntp_to_date(struct calendar * /* jd */,	uint32_t /* ntp */,
325		   const time_t * /* pivot */);
326
327extern vint64
328ntpcal_date_to_ntp64(const struct calendar * /* jd */);
329
330extern uint32_t
331ntpcal_date_to_ntp(const struct calendar * /* jd */);
332
333extern time_t
334ntpcal_date_to_time(const struct calendar * /* jd */);
335
336/*
337 * ISO week-calendar conversions
338 */
339extern int32_t
340isocal_weeks_in_years(int32_t  /* years */);
341
342/*
343 * The input is limited to [-2^30, 2^30-1]. If the weeks exceed this
344 * range, errno is set to EDOM and the result is saturated.
345 */
346extern ntpcal_split
347isocal_split_eraweeks(int32_t /* weeks */);
348
349extern int
350isocal_ntp64_to_date(struct isodate * /* id */, const vint64 * /* ntp */);
351
352extern int
353isocal_ntp_to_date(struct isodate * /* id */, uint32_t /* ntp */,
354		   const time_t * /* pivot */);
355
356extern vint64
357isocal_date_to_ntp64(const struct isodate * /* id */);
358
359extern uint32_t
360isocal_date_to_ntp(const struct isodate * /* id */);
361
362
363/*
364 * day-of-week calculations
365 *
366 * Given a RataDie and a day-of-week, calculate a RDN that is reater-than,
367 * greater-or equal, closest, less-or-equal or less-than the given RDN
368 * and denotes the given day-of-week
369 */
370extern int32_t
371ntpcal_weekday_gt(int32_t  /* rdn */, int32_t /* dow */);
372
373extern int32_t
374ntpcal_weekday_ge(int32_t /* rdn */, int32_t /* dow */);
375
376extern int32_t
377ntpcal_weekday_close(int32_t /* rdn */, int32_t  /* dow */);
378
379extern int32_t
380ntpcal_weekday_le(int32_t /* rdn */, int32_t /* dow */);
381
382extern int32_t
383ntpcal_weekday_lt(int32_t /* rdn */, int32_t /* dow */);
384
385/*
386 * Additional support stuff for Ed Rheingold's calendrical calculations
387 */
388
389/*
390 * Start day of NTP time as days past the imaginary date 12/1/1 BC.
391 * (This is the beginning of the Christian Era, or BCE.)
392 */
393#define	DAY_NTP_STARTS 693596
394
395/*
396 * Start day of the UNIX epoch. This is the Rata Die of 1970-01-01.
397 */
398#define DAY_UNIX_STARTS 719163
399
400/*
401 * Difference between UN*X and NTP epoch (25567).
402 */
403#define NTP_TO_UNIX_DAYS (DAY_UNIX_STARTS - DAY_NTP_STARTS)
404
405/*
406 * Days in a normal 4 year leap year calendar cycle (1461).
407 */
408#define	GREGORIAN_NORMAL_LEAP_CYCLE_DAYS	(3 * 365 + 366)
409
410/*
411 * Days in a normal 100 year leap year calendar (36524).  We lose a
412 * leap day in years evenly divisible by 100 but not by 400.
413 */
414#define	GREGORIAN_NORMAL_CENTURY_DAYS	\
415			(25 * GREGORIAN_NORMAL_LEAP_CYCLE_DAYS - 1)
416
417/*
418 * The Gregorian calendar is based on a 400 year cycle. This is the
419 * number of days in each cycle (146097).  We gain a leap day in years
420 * divisible by 400 relative to the "normal" century.
421 */
422#define	GREGORIAN_CYCLE_DAYS (4 * GREGORIAN_NORMAL_CENTURY_DAYS + 1)
423
424/*
425 * Number of weeks in 400 years (20871).
426 */
427#define	GREGORIAN_CYCLE_WEEKS (GREGORIAN_CYCLE_DAYS / 7)
428
429#define	is_leapyear(y)	(!((y) % 4) && !(!((y) % 100) && (y) % 400))
430
431#endif
432