And if you notice, I just toss an error value for when we end up below 1970 and look for a timestamp. At that point, we have to count time in reverse to generate negative numbers, and I just didn't feel like putting in the effort for it. :P
DEC 31, 1969, 23:59:59 = -1
DEC 31, 1969, 23:59:58 = -2
... and so on.
With the medications I'm on, I'm surprised I managed to count forward to get to the point where it's currently working properly; I sure don't feel like making it count backwards at the moment. I leave that mod to Bplus, if he feels like adding it, otherwise positive timestamps are good enough for my needs... ;)