[hatari-devel] Re : DSP host interface interrupted mode : help needed

[Thomas Huth]

On Mon, 14 Sep 2009 15:40:38 +0200
LAURENT SALLAFRANQUE <LAURENT.SALLAFRANQUE at ARKEA.COM> wrote:

>  From what I've understood of the google traduction of the german 
> message :), it seems that the DSP sends its interrupt to the COMBEL
> chip and not directly to the MFP chip. The COMBEL gather MFP and DSP 
> interrupts at level 6, and interrupts the 68030.
> 
> But, as the COMBEL isn't adressable by software (it's a pure hardware 
> chip) and as the MFP does already a big part of the COMBEL job, could
> we imagine to just upgrade the actual MFP code to MFP/COMBEL chip 
> management. We could add the lightgun interrupt later if needed ;)
> 
> Like this, the DSP interrupt could be easily added to the MFP code
> (at interrupt level 6).
> I think, the level of interrupt musn't be too high, as the DSP is 
> waiting for the host to feed him with datas.
> That's not crucial (as a VSYNC is for example).

Well, we have to make sure that we run the interrupt at the right
priority or software might crash. Imagine for example, that a programs
uses both, VBL and DSP interrupt. When the DSP interrupt routine is
suddenly interrupted by the VBL routine (which certainly can not happen
on a real Falcon), then it have strange side effects...

> As I don't know well the MFP part, would you (Thomas), add the
> interrupt ?
> 
> (I can add the "dsp_get_HREQ()" function in dsp.c if you want it to
> be coded this way).

Ok, please prepare the code, then tell me where I can add the code that
should trigger the interrupt, then I'll have a try.

 Thomas