[hatari-devel] some videl emulation news

[Nicolas Pomarède]

Le 06/06/2011 21:45, Laurent Sallafranque a écrit :
>  > are you sure of this?
>
> No, it's only a guess.
>
> I've guessed it from 2 things I read :
>
> - the ST Shifter fills it's internal buffer at end of HBL. I think this
> could be the same behaviour for the Videl.

?? What do you mean ? The Shifter has no "per hbl" internal buffer ; it 
has 4 internal 16 bits registers that are permanently "rotated" and 4 
others 16 bits registers that are reloaded every 16 cycles (in low res).
There're some very good/technical articles on this by Alien/STCNX that 
were published in french ST Magazine 51/52 (and translated in the 
"Alive" mag).

Hatari emulates one HBL at a time, but that's not the real way it works, 
it's because rendering lines in chunk of 16 pixels would kill the 
performance.

I don't think the falcon has some internal buffer to store one complete 
HBL line, I don't see what would be the purpose of this at the hardware 
level.

Nicolas

> - I'm pretty sure I've read it somewhere, but I can't find where.
>
> Anyway, only good benchs would confirm that.
>
>
> Regards
>
> Laurent
>