[A83] Re: Inverting graph buffer in one time

To: assembly-83@lists.ticalc.org
Subject: [A83] Re: Inverting graph buffer in one time
From: Tijl Coosemans <tijl.coosemans@mail.be>
Date: Mon, 29 Oct 2001 21:32:28 +0100
Reply-To: assembly-83@lists.ticalc.org


> From: Peter-Martijn Kuipers <hyper@hysoft-automation.com>
> 
> > Actual routine from Penguins (courtesy Bill Nagel):
> > 
> > invert:
> >      ld   bc,768
> >      ld   hl,plotsscreen
> > inv_loop:
> >      ld   a,(hl)
> >      cpl
> >      ld   (hl),a
> >      inc  hl
> >      dec  bc
> >      ld   a,b
> >      or   c

> Good trick to compare bc with zero...

It is used extensively in the TIOS... It's about the only thing in the TIOS that one can call 'optimized code' (at least in my calc).
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