Re: [hatari-devel] Re: [Emutos-devel] Aranym blitter

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 07/06/2017 à 23:21, Eero Tamminen a écrit :

> > What's a bit unclear to me is:
> > - what happens on real hardware when accessing the word registers with 
> > byte
> > moves? That is not handled yet by aranym.

Hi

This was already verified on real STE/Mega STE. See 
tests/buserror/results/ folder in Hatari directory. It shows that word 
and bytes accesses don't give bus error between FF8A00 and FF8A40 (IIRC 
Atari's blitter doc says only word acceses are possible, but it's wrong)


> > - what happens to the source address, when no data is read? is it stll
> > incremented/decremented?

I don't think it's possible in "normal" case to not read anything in 
source. The only case I see is the one we talked about in another thread 
when xcount=1 and FXSR/NFSR are set to 0 or 1. For now, there's no known 
rule of how the blitter works in this special case (christian might have 
an answer when he gets time to analyze the ste shifter)

BTW christian, in the different tests you made, we saw that sometimes 
nothing is written in dest. Could you add the number of words 
read/written to the output of your test program ? (by subtracting start 
source/dest address to end source/dest address). Maybe sometimes nothing 
is written to dest but words are still read anyway ?



Nicolas