/*
* set the function for getting the system time. This is mostly used for
* unit testing to provide a fixed / shifted time stamp. Setting the
* value to NULL restores the original function, that is, 'time()',
* which is also the automatic default.
*/
extern systime_func_ptr ntpcal_set_timefunc(systime_func_ptr);
/*
* 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 DAYSPERWEEK (7) /* days per week */
#define DAYSPERYEAR (365) /* days per year */
#define SECSPERHR (SECSPERMIN * MINSPERHR)
#define SECSPERDAY (SECSPERHR * HRSPERDAY)
#define SECSPERWEEK (DAYSPERWEEK * SECSPERDAY)
#define SECSPERYEAR (365 * SECSPERDAY) /* regular year */
#define SECSPERLEAPYEAR (366 * SECSPERDAY) /* leap year */
#define SECSPERAVGYEAR 31556952 /* mean year length over 400yrs */
/*
* Convert between 'time_t' and 'vint64'
*/
extern vint64 time_to_vint64(const time_t *);
extern time_t vint64_to_time(const vint64 *);
/*
* Get the build date & time. ATTENTION: The time zone is not specified!
* This depends entirely on the C compilers' capabilities to properly
* expand the '__TIME__' and '__DATE__' macros, as required by the C
* standard.
*/
extern int
ntpcal_get_build_date(struct calendar * /* jd */);
/*
* Convert a timestamp in NTP scale to a time_t value in the UN*X
* scale with proper epoch unfolding around a given pivot or the
* current system time.
*/
extern vint64
ntpcal_ntp_to_time(uint32_t /* ntp */, const time_t * /* pivot */);
/*
* Convert a timestamp in NTP scale to a 64bit seconds value in the NTP
* scale with proper epoch unfolding around a given pivot or the current
* system time.
* Note: The pivot must be given in UN*X time scale!
*/
extern vint64
ntpcal_ntp_to_ntp(uint32_t /* ntp */, const time_t * /* pivot */);
/*
* Split a time stamp in seconds into elapsed days and elapsed seconds
* since midnight.
*/
extern ntpcal_split
ntpcal_daysplit(const vint64 *);
/*
* Split a time stamp in seconds into elapsed weeks and elapsed seconds
* since start of week.
*/
extern ntpcal_split
ntpcal_weeksplit(const vint64 *);
/*
* Merge a number of days and a number of seconds into seconds,
* expressed in 64 bits to avoid overflow.
*/
extern vint64
ntpcal_dayjoin(int32_t /* days */, int32_t /* seconds */);
/*
* Merge a number of weeks and a number of seconds into seconds,
* expressed in 64 bits to avoid overflow.
*/
extern vint64
ntpcal_weekjoin(int32_t /* weeks */, int32_t /* seconds */);
/* Get the number of leap years since epoch for the number of elapsed
* full years
*/
extern int32_t
ntpcal_leapyears_in_years(int32_t /* years */);
/*
* Convert elapsed years in Era into elapsed days in Era.
*/
extern int32_t
ntpcal_days_in_years(int32_t /* years */);
/*
* Convert a number of elapsed month in a year into elapsed days
* in year.
*
* The month will be normalized, and 'res.hi' will contain the
* excessive years that must be considered when converting the years,
* while 'res.lo' will contain the days since start of the
* year. (Expect the resulting days to be negative, with a positive
* excess! But then, we need no leap year flag, either...)
*/
extern ntpcal_split
ntpcal_days_in_months(int32_t /* months */);
/*
* Convert ELAPSED years/months/days of gregorian calendar to elapsed
* days in Gregorian epoch. No range checks done here!
*/
extern int32_t
ntpcal_edate_to_eradays(int32_t /* years */, int32_t /* months */, int32_t /* mdays */);
/*
* Convert a time spec to seconds. No range checks done here!
*/
extern int32_t
ntpcal_etime_to_seconds(int32_t /* hours */, int32_t /* minutes */, int32_t /* seconds */);
/*
* Convert ELAPSED years/months/days of gregorian calendar to elapsed
* days in year.
*
* Note: This will give the true difference to the start of the given year,
* even if months & days are off-scale.
*/
extern int32_t
ntpcal_edate_to_yeardays(int32_t /* years */, int32_t /* months */, int32_t /* mdays */);
/*
* Convert the date part of a 'struct tm' (that is, year, month,
* day-of-month) into the RataDie of that day.
*/
extern int32_t
ntpcal_tm_to_rd(const struct tm * /* utm */);
/*
* Convert the date part of a 'struct calendar' (that is, year, month,
* day-of-month) into the RataDie of that day.
*/
extern int32_t
ntpcal_date_to_rd(const struct calendar * /* jt */);
/*
* Given the number of elapsed days in the calendar era, split this
* number into the number of elapsed years in 'res.quot' and the
* number of elapsed days of that year in 'res.rem'.
*
* if 'isleapyear' is not NULL, it will receive an integer that is 0
* for regular years and a non-zero value for leap years.
*
* The input is limited to [-2^30, 2^30-1]. If the days exceed this
* range, errno is set to EDOM and the result is saturated.
*/
extern ntpcal_split
ntpcal_split_eradays(int32_t /* days */, int/*BOOL*/ * /* isleapyear */);
/*
* Given a number of elapsed days in a year and a leap year indicator,
* split the number of elapsed days into the number of elapsed months
* in 'res.quot' and the number of elapsed days of that month in
* 'res.rem'.
*/
extern ntpcal_split
ntpcal_split_yeardays(int32_t /* eyd */, int/*BOOL*/ /* isleapyear */);
/*
* Convert a RataDie number into the date part of a 'struct
* calendar'. Return 0 if the year is regular year, !0 if the year is
* a leap year.
*/
extern int/*BOOL*/
ntpcal_rd_to_date(struct calendar * /* jt */, int32_t /* rd */);
/*
* Convert a RataDie number into the date part of a 'struct
* tm'. Return 0 if the year is regular year, !0 if the year is a leap
* year.
*/
extern int/*BOOL*/
ntpcal_rd_to_tm(struct tm * /* utm */, int32_t /* rd */);
/*
* Take a value of seconds since midnight and split it into hhmmss in
* a 'struct calendar'. Return excessive days.
*/
extern int32_t
ntpcal_daysec_to_date(struct calendar * /* jt */, int32_t /* secs */);
/*
* Take the time part of a 'struct calendar' and return the seconds
* since midnight.
*/
extern int32_t
ntpcal_date_to_daysec(const struct calendar *);
/*
* Take a value of seconds since midnight and split it into hhmmss in
* a 'struct tm'. Return excessive days.
*/
extern int32_t
ntpcal_daysec_to_tm(struct tm * /* utm */, int32_t /* secs */);
/*
* convert a year number to rata die of year start
*/
extern int32_t
ntpcal_year_to_ystart(int32_t /* year */);
/*
* For a given RataDie, get the RataDie of the associated year start,
* that is, the RataDie of the last January,1st on or before that day.
*/
extern int32_t
ntpcal_rd_to_ystart(int32_t /* rd */);
/*
* convert a RataDie to the RataDie of start of the calendar month.
*/
extern int32_t
ntpcal_rd_to_mstart(int32_t /* year */);
extern int
ntpcal_daysplit_to_date(struct calendar * /* jt */,
const ntpcal_split * /* ds */, int32_t /* dof */);
/*
* ISO week-calendar conversions
*/
extern int32_t
isocal_weeks_in_years(int32_t /* years */);
/*
* The input is limited to [-2^30, 2^30-1]. If the weeks exceed this
* range, errno is set to EDOM and the result is saturated.
*/
extern ntpcal_split
isocal_split_eraweeks(int32_t /* weeks */);
extern int
isocal_ntp64_to_date(struct isodate * /* id */, const vint64 * /* ntp */);
extern int
isocal_ntp_to_date(struct isodate * /* id */, uint32_t /* ntp */,
const time_t * /* pivot */);
extern vint64
isocal_date_to_ntp64(const struct isodate * /* id */);
extern uint32_t
isocal_date_to_ntp(const struct isodate * /* id */);
/*
* day-of-week calculations
*
* Given a RataDie and a day-of-week, calculate a RDN that is reater-than,
* greater-or equal, closest, less-or-equal or less-than the given RDN
* and denotes the given day-of-week
*/
extern int32_t
ntpcal_weekday_gt(int32_t /* rdn */, int32_t /* dow */);
extern uint32_t
basedate_expand_gpsweek(unsigned short weekno);
/*
* Additional support stuff for Ed Rheingold's calendrical calculations
*/
/*
* Start day of NTP time as days past 0000-12-31 in the proleptic
* Gregorian calendar. (So 0001-01-01 is day number 1; this is the Rata
* Die counting scheme used by Ed Rheingold in his book "Calendrical
* Calculations".)
*/
#define DAY_NTP_STARTS 693596
/*
* Start day of the UNIX epoch. This is the Rata Die of 1970-01-01.
*/
#define DAY_UNIX_STARTS 719163
/*
* Start day of the GPS epoch. This is the Rata Die of 1980-01-06
*/
#define DAY_GPS_STARTS 722820
/*
* Difference between UN*X and NTP epoch (25567).
*/
#define NTP_TO_UNIX_DAYS (DAY_UNIX_STARTS - DAY_NTP_STARTS)
/*
* Difference between GPS and NTP epoch (29224)
*/
#define NTP_TO_GPS_DAYS (DAY_GPS_STARTS - DAY_NTP_STARTS)
/*
* Days in a normal 4 year leap year calendar cycle (1461).
*/
#define GREGORIAN_NORMAL_LEAP_CYCLE_DAYS (4 * 365 + 1)
/*
* Days in a normal 100 year leap year calendar (36524). We lose a
* leap day in years evenly divisible by 100 but not by 400.
*/
#define GREGORIAN_NORMAL_CENTURY_DAYS \
(25 * GREGORIAN_NORMAL_LEAP_CYCLE_DAYS - 1)
/*
* The Gregorian calendar is based on a 400 year cycle. This is the
* number of days in each cycle (146097). We gain a leap day in years
* divisible by 400 relative to the "normal" century.
*/
#define GREGORIAN_CYCLE_DAYS (4 * GREGORIAN_NORMAL_CENTURY_DAYS + 1)
/*
* Number of weeks in 400 years (20871).
*/
#define GREGORIAN_CYCLE_WEEKS (GREGORIAN_CYCLE_DAYS / 7)
/*
* Is a Greogorian calendar year a leap year? The obvious solution is to
* test the expression
*
* (y % 4 == 0) && ((y % 100 != 0) || (y % 400 == 0))
*
* This needs (in theory) 2 true divisions -- most compilers check the
* (mod 4) condition by doing a bit test. Some compilers have been
* even observed to partially fuse the (mod 100) and (mod 400) test,
* but there is an alternative formula that gives the compiler even
* better chances:
*
* (y % 4 == 0) && ((y % 16 == 0) || (y % 25 != 0))
*
* The order of checks is chosen so that the shorcut evaluation can fix
* the result as soon as possible. And the compiler has to do only one
* true division here -- the (mod 4) and (mod 16) can be done with
* direct bit tests. *If* the compiler chooses to do so.
*
* The deduction is as follows: rewrite the standard formula as
* (y % 4 == 0) && ((y % 4*25 != 0) || (y % 16*25 == 0))
*
* then split the congruences:
* (y % 4 == 0) && ((y % 4 != 0 || y % 25 != 0) || (y % 16 == 0 && y % 25 == 0))
*
* eliminate the 1st inner term, as it is provably false:
* (y % 4 == 0) && (y % 25 != 0 || (y % 16 == 0 && y % 25 == 0))
*
* Use the distributive laws on the second major group:
* (y % 4 == 0) && ((y % 25 != 0 || y % 16 == 0) && (y % 25 != 0 || y % 25 == 0))
*
* Eliminate the constant term, reorder, and voila:
*/
static inline int
is_leapyear(int32_t y) {
return !(y % 4) && (!(y % 16) || (y % 25));
}
/* The (mod 4) test eliminates 3/4 (or 12/16) of all values.
* The (mod 16) test eliminates another 1/16 of all values.
* 3/16 of all values reach the final division.
* Assuming that the true division is the most costly operation, this
* sequence should give most bang for the buck.
*/
/* misc */
extern int u32mod7(uint32_t x);
extern int i32mod7(int32_t x);
extern uint32_t i32fmod(int32_t x, uint32_t d);
extern int32_t ntpcal_expand_century(uint32_t y, uint32_t m, uint32_t d, uint32_t wd);
