date/time parsing

[utzoo!duke!decvax!ucbvax!mclure at SRI-Unix]

I'm looking for routine(s) that parse date/time strings such as
those produced by ctime(3) and convert them to long's as produced
by time(2). Does anyone have such a thing? Also, it would be
nice if they allowed generalized strings like the TOPS-20
date/time parsing.