freebsd-src/contrib/ntp/libntp/ymd2yd.c
1999-12-09 13:01:21 +00:00

38 lines
677 B
C

/*
* ymd2yd - compute the date in the year from y/m/d
*/
#include "ntp_fp.h"
#include "ntp_unixtime.h"
#include "ntp_stdlib.h"
/*
* Tables to compute the day of year from yyyymmdd timecode.
* Viva la leap.
*/
static int day1tab[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
static int day2tab[] = {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int
ymd2yd(
int y,
int m,
int d
)
{
int i, *t;
if (m < 1 || m > 12 || d < 1)
return (-1);
if (((y%4 == 0) && (y%100 != 0)) || (y%400 == 0))
t = day2tab; /* leap year */
else
t = day1tab; /* not a leap year */
if (d > t[m - 1])
return (-1);
for (i = 0; i < m - 1; i++)
d += t[i];
return d;
}