[Vm-dev] simulation in BitBltSimulation

[Nicolas Cellier]

2014-03-15 2:44 GMT+01:00 tim Rowledge <tim at rowledge.org>:

>
>
> On 14-03-2014, at 6:16 PM, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>
> > Hi Tim,
> >
> >     I'm simulating bitblt code and have a situation where
> >
> > (cmShiftTable at: 0) = 4294967280
> > (cmShiftTable at: 0) hex '16rFFFFFFF0'
> >
> > Clearly this should be -4.
> >
>

I presume you mean - 2^4 (-2r1e4 or -16) ;)


> > This breaks simulation because
> >         (sourcePixel bitAnd: (cmMaskTable at: 0)) bitShift:
> (cmShiftTable at: 0)
> > is trying to make a 4Gb LargePositiveInteger ;-).
> >
> > How can we make it so?
>
> Hmm, well if you need to make a 4Gb LPI I guess you'd best have plenty of
> memory?
>
> Dunno; looks like cmShiftTable is supposed to use int32_t thingies in the
> C code.
> BitBltSimulation>loadColorMapShiftOrMaskFrom: looks like the culprit to me
> though -  (simulated)firstIndexableField: might be not doing the right
> thing?
>
> tim
> --
> tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
> Useful random insult:- Always loses battles of wits because he's unarmed.
>
>
>
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