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freebsd/contrib/ntp/libntp/caltontp.c
1999-12-09 13:01:21 +00:00

43 lines
1017 B
C

/*
* caltontp - convert a date to an NTP time
*/
#include <sys/types.h>
#include "ntp_types.h"
#include "ntp_calendar.h"
#include "ntp_stdlib.h"
u_long
caltontp(
register const struct calendar *jt
)
{
u_long ace_days; /* absolute Christian Era days */
u_long ntp_days;
int prior_years;
u_long ntp_time;
/*
* First convert today's date to absolute days past 12/1/1 BC
*/
prior_years = jt->year-1;
ace_days = jt->yearday /* days this year */
+(DAYSPERYEAR*prior_years) /* plus days in previous years */
+(prior_years/4) /* plus prior years's leap days */
-(prior_years/100) /* minus leapless century years */
+(prior_years/400); /* plus leapful Gregorian yrs */
/*
* Subtract out 1/1/1900, the beginning of the NTP epoch
*/
ntp_days = ace_days - DAY_NTP_STARTS;
/*
* Do the obvious:
*/
ntp_time =
ntp_days*SECSPERDAY+SECSPERMIN*(MINSPERHR*jt->hour + jt->minute);
return ntp_time;
}