Re: [hatari-devel] Suggested patch to fix problem handling STOP when DSP is active

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

On 10/30/20 4:13 AM, Roger Burrows wrote:
> On 29 Oct 2020 at 22:41, Nicolas Pomarède wrote:
> > But doing it on a 100 cycles basis is not really fully accurate, so I
> > did the attached patch where DSP_Run is called on each loop during the
> > STOP state (at the interval where MFP is updated too).
> >
> > Please check if it improves sound in your case (maybe it will require
> > more CPU than your patch on every 100 cycles)
> OK, I've tested it.  At my normal settings (16MHz system), I can't really tell
> any difference between your patch and mine.  Neither is perfect.  The audio
> runs a little slow, and there are lots of artifacts, although the main tune is
> quite distinct (which it isn't with the unpatched system).
>
> However, if I change to an 8MHz 68030 clock, the sound improves for both
> patches - but the sound with my patch is noticeably better.  I think that this
> shows that my system is just not fast enough: although reducing the speed of
> the emulated 68030 allows more time for everything else to run properly, it's
> not quite enough for the extra requirements of the DSP.  Calling Dsp_Run() less
> often then makes just enough difference to be noticeable, and is more
> beneficial than an increased accuracy of emulation.

Hatari aims to be as accurate as possible.  There are still few programs 
(demos) that don't run
at all because of the current CPU<->DSP
inaccuracies.

=> I think Hatari should do the correct thing,
   instead of a fast one.


> I don't think you should pay too much attention to how my system runs.  It's an
> AMD Athlon 64 3200+ which has a CPU Mark score of 332.  My Windoze system
> (which is by no means new) is an AMD Phenom II X4 955 with a score of 2430 ...

I need to get a faster computer too, my current
one is decade old.  I've planned on getting one
for half of that time, but for reason or another
it's always gotten post-poned...

(For Hatari Falcon emulation, only sustained
single core perf matter.)


	- Eero