Function clock_ct_to_ts

freebsd/kern/subr_clock.c:138–196

}

int
clock_ct_to_ts(const struct clocktime *ct, struct timespec *ts)
{
	int i, year, days;

	if (ct_debug) {
		printf("ct_to_ts([");
		clock_print_ct(ct, 9);
		printf("])");
	}

	/*
	 * Many realtime clocks store the year as 2-digit BCD; pivot on 70 to
	 * determine century.  Some clocks have a "century bit" and drivers do
	 * year += 100, so interpret values between 70-199 as relative to 1900.
	 */
	year = ct->year;
	if (year < 70)
		year += 2000;
	else if (year < 200)
		year += 1900;

	/* Sanity checks. */
	if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
	    ct->day > days_in_month(year, ct->mon) ||
	    ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 || year < 1970 ||
	    (sizeof(time_t) == 4 && year > 2037)) {	/* time_t overflow */
		if (ct_debug)
			printf(" = EINVAL\n");
		return (EINVAL);
	}

	/*
	 * Compute days since start of time
	 * First from years, then from months.
	 */
	if (year >= recent_base_year) {
		i = recent_base_year;
		days = recent_base_days;
	} else {
		i = POSIX_BASE_YEAR;
		days = 0;
	}
	for (; i < year; i++)
		days += days_in_year(i);

	/* Months */
	for (i = 1; i < ct->mon; i++)
	  	days += days_in_month(year, i);
	days += (ct->day - 1);

	ts->tv_sec = (((time_t)days * 24 + ct->hour) * 60 + ct->min) * 60 +
	    ct->sec;
	ts->tv_nsec = ct->nsec;

	if (ct_debug)
		printf(" = %jd.%09ld\n", (intmax_t)ts->tv_sec, ts->tv_nsec);
	return (0);