I have been looking at the 16 bit math routines at
http://www.myke.com/PICMicro/16bit.htm and I was wondering if
someone can tell me by looking at the subtraction routine(s) there, if they
handle negative numbers.  I am going to need to do things where I am ending
up with a final result that is a positive number, maybe dividing a negative
by a negative, but I want to know if these routines will do negative numbers
for my intermediate steps.  If now, how can I?