Aw: Re: [stella] 6502 questions

Subject: Aw: Re: [stella] 6502 questions
From: cybergoth@xxxxxxxx
Date: Thu, 11 Oct 2001 18:58:27 +0200 (CEST)
Hi Erik!

> BPL branches if the MINUS flag is not set. [...]
> [...] the MINUS flag is not set, and BPL won't branch.

Well. Confusing topic :-)

I'm not sure, but maybe you just can't do a simple compare 
which number is bigger in _signed_ 8-Bit math. The results
are somewhat unpredictable I'd say. Maybe you've to test some 
cases (A neg? B neg? A>$80? B>80?) first, and then branch into the 
correct handling routine.

According to the problem that is to be solved, I'd avoid such
braintrashing stuff anyway. Most of the times there's a way simpler
solution, for example in the given problem you could add #20 to both
values to bail out of most troubles...

Besides: For > & < questions the carry is more important than 
the minus flag anyway...


Für Schnäppchenjäger ist jetzt Beutemachen angesagt:
Quelle hat knallhart reduziert. Aber nur solange Vorrat reicht!

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