[A83] Re: Inverting graph buffer in one time


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[A83] Re: Inverting graph buffer in one time




> 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

Good trick to compare bc with zero...
>      ld   a,b
>      or   c
---

>      jr   nz,inv_loop
> 
>      ret
> 
> 
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> 
> 





References: