Re: [hatari-devel] Microwire register value on Falcon

["Thomas H." <th.huth@xxxxxx>]

> Datum: Wed, 01 Feb 2012 23:52:42 +0100
> Von: Laurent Sallafranque <laurent.sallafranque@xxxxxxx>
>
> Hi,
> 
> Thanks a lot too for the tests.
> 
> So, it seems that $ff8922 always return 0 and $ff8924 returns $7ff 
> except the first time (a change, then the mask value).
> 
> I think it could be OK to just return $7ff, but a program may test if 
> the value is different and then equal.
> As I've never encountered this before, I think we can just return $7ff 
> and add a comment in iomemtabfalcon for this $f800 value, for later if 
> needed.

Well, I don't think that forcing this register to 0x7ff makes much sense, since you can write arbitrary masks to it, I rather think that this register always returns the same value that you've written to it (expect for the first read apparently).

I've changed the code to use Read+WriteWithoutInterception now, that should be fine until we encounter a program that needs this different value during the first read - then we've got to investigate a little bit more.

> Thomas, instead of a return0 function, wouldn't it be better to have a 
> returnFixValue (thevalue) one ?
> 
> we could do : returnFixValue(0) for $ff8922 and returnFixValue($7ff) for 
> $ff8924

That does not work since we're storing function pointers in the table, and you can not specify parameters to a function pointer.

 Thomas

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