Re: [hatari-devel] error reading video counter on TT since commit 5316b4081e9d3

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 23/07/2022 à 08:09, Thomas Huth a écrit :

> Instead of reverting, I'd suggest that we just add a special "else" case
> here to fake a video counter update in TT and Falcon mode, e.g.:
>
> 	if (!Config_IsMachineTT() && !Config_IsMachineFalcon())
> 	{
> 		Video_EndHBL();
> 	}
> 	else
> 	{
> 		/* Fake video counter update in TT and Falcon mode...
> 		 * should be replaced once we have more precise video
> 		 * emulation there: */
> 		pVideoRaster = ((pVideoRaster - STRam + SCREENBYTES_MIDDLE)
> 		                & 0xffffff) + STRam;
> 	}
>
> SCREENBYTES_MIDDLE should maybe be adjusted depending on the video mode...
> Does that sound acceptable?

Hi

I'm not sure this would be fail proof enough ; in the case of 
hextracker, it compares with video addr at start of screen, but some 
other program could wait for line 1 or end of screen for example. Also 
you should not return the above value unless DE has really started (ie 
not during top border) or it will mess with other cases/

> Alternatively, we could also introduce TT-specific versions of
> Video_ScreenCounter_ReadByte(), just like we did with
> VIDEL_ScreenCounter_ReadByte() already.

Yes, I think it would be better. For example add a similar call to 
VIDEL_VideoRasterHBL() done in Video_InterruptHandler_HBL() to update 
pVideoRaster in TT case with sthg like "bytes per line * nHBL"

I will have a look if you don't plan doing it youself ? (I think I can 
patch it today)

Nicolas