[aprssig] TNC command formats

Bill Herrmann bherrman at spro.net
Thu Mar 17 00:29:00 CST 2005

At 03:25 PM 3/16/2005 -0800, Scott Miller wrote:
>match what you'd entered.  You'd get ver<tab>SION.  Not that bad, but the
>lack of a case-insensitive string compare makes it harder.  If I think of a
>clean way to do it, I'll try.

Just a vague memory here and I don't have time to look it up, but....

I'm pretty sure that in ASCII the difference between an upper case letter 
and a lower case letter is a single bit (set for lower case and clear for 
upper). It shouldn't be too hard to mask that bit for the compare or apply 
it to the added portion of the command in order to match the case. If you 
choose to try and match the case I'd suggest borrowing the bit from the 
last character the user entered.
i.e. if I enter He make the resulting command Help where if you used the 
first character you would get HeLP.


p.s. Careful of numbers and special characters as they don't hold up if you 
muck with that bit. (Interestingly numbers, at least, do in EBCDIC.) 

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