HelenOS sources

wbyear_offset     410 uspace/lib/c/generic/time.c 	int day = tm->tm_yday - wbyear_offset(tm->tm_year);
wbyear_offset     458 uspace/lib/c/generic/time.c 	int day = tm->tm_yday - wbyear_offset(tm->tm_year);
HelenOS homepage, sources at GitHub