Re: [hatari-devel] Videl / VBL interrupt issue in Hatari?

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

On maanantai 20 tammikuu 2014, Mariusz Buras wrote:
> Right, I only use old CPU emulation (don't know why, I might have some
> reasons - perhaps better compatibility?).

WinUAE CPU core is more compatible only for Falcon emulation
(and I think even there, there are still couple of cases which
work better with old UAE CPU core).  If you want MP2 DSP playback,
you need WinUAE CPU core for example.


	- Eero

> > Hi,
> > 
> > From what I see everyday, it's the opposite : hatari (falcon emu, new
> > core) is much faster than a real Falcon.
> > 
> > An example : Racer (actual dev release runs in 4 VBLs, whereas under
> > hatari, it runs in 3 VBLs
> > 
> > doing a loop like this :
> >               move.w #240-1,d1
> > 
> > .outer_loop:  move.w #320/2-1,d0
> > .inner_loop : move.l (a0)+,(a1)+
> > 
> >               dbf    d0,.inner_loop
> >               dbf    d1,.outer_loop
> > 
> > takes 6 VBLs under real hardware and only 4 VBLs under Hatari.
> > 
> > And I only speak about the "Real time" emulation, which takes quite
> > correct cycles into account.
> > The MMU emulation (used by Doug) doesn't take into account the
> > instructions cycles (nearly every instruction takes 2 cycles, so Hatari
> > runs a lot too fast in MMU emulation mode).
> > 
> > The cache instruction mode is not completly accurate, but not that bad
> > either.
> > It may increase the speed difference by a little if activated, but I
> > don't think this can be the real problem.
> > 
> > This probably join the precedent threads about Falcon accuracy (I don't
> > speak about exact accuracy, but close accuracy here, of course).
> > 
> > Regards
> > Laurent
> > 
> > 
> > 
> > ----- Mail original -----
> > De: "Nicolas Pomarède" <npomarede@xxxxxxxxxxxx>
> > À: hatari-devel@xxxxxxxxxxxxxxxxxxx
> > Cc: "Mariusz Buras" <mariusz.buras@xxxxxxxxx>
> > Envoyé: Lundi 20 Janvier 2014 13:15:45
> > Objet: Re: [hatari-devel] Videl / VBL interrupt issue in Hatari?
> > 
> > Le 20/01/2014 13:11, Mariusz Buras a écrit :
> > > Well, for instance, if your VBL routine would take almost entire
> > > frame to execute on real falcon, on Hatari it could be more then one
> > > frame to do the same task, so they would overlap.
> > 
> > AFAIK, BM doesn't run in 1 VBL on falcon anyway, more like 2 or 3 VBL
> > per frame.
> > 
> > So this problem should already be taken into account, else it would not
> > work as soon as the 1st seconds of game.
> > Usually, when program doesn't run in 1 VBL, you will use a short VBL
> > code that mostly only set a VBL counter + a few others things that
> > really need to be real time (sound, music, ...), and then the main
> > program (outside of the VBL) waits for the counter to change before
> > working on the next frame.
> > 
> > Nicolas