- diff_min = 60*(local.tm_hour - gmt->tm_hour) + local.tm_min - gmt->tm_min;
- if (local.tm_year != gmt->tm_year)
- diff_min += (local.tm_year > gmt->tm_year)? 1440 : -1440;
- else if (local.tm_yday != gmt->tm_yday)
- diff_min += (local.tm_yday > gmt->tm_yday)? 1440 : -1440;
- diff_hour = diff_min/60;
- diff_min = abs(diff_min - diff_hour*60);
+ if (local.tm_sec == gmt->tm_sec) /* usual case */
+ {
+ diff_min = 60 * (local.tm_hour - gmt->tm_hour)
+ + local.tm_min - gmt->tm_min;
+ if (local.tm_year != gmt->tm_year)
+ diff_min += (local.tm_year > gmt->tm_year) ? 1440 : -1440;
+ else if (local.tm_yday != gmt->tm_yday)
+ diff_min += (local.tm_yday > gmt->tm_yday) ? 1440 : -1440;
+ diff_hour = diff_min/60;
+ diff_min = abs(diff_min - diff_hour*60);
+ }
+ else /* subminute offset, eg. TAI */
+ {
+ lp = gmt; /* pretend we're in UTC */
+ diff_min = diff_hour = 0;
+ }