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From: CBFalconer <cbfalconer AT yahoo DOT com>
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Subject: Re: Cross Platform Incompatabilites? - code fragments
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Date: Thu, 19 Feb 2004 02:00:44 GMT
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Eli Zaretskii wrote:
> From: CBFalconer <cbfalconer AT yahoo DOT com>
> > >
> > > I thought about something like that, but this could only have
> > > effect on programs that trigger exceptions, no?
> >
> > Such as events triggered by the timers, giving time slices to
> > other processes, etc.
> 
> I don't think so.  Do you have examples?

No.  I do remember cases in the CP/M days when certain evil bioses
in the Osborne I altered and did not save some Z80 registers
"because CP/M doesn't use them".  This created havoc, and I
carefully wrote my CP/M replacement to protect those values.

> 
> A multitasking, multiprocessing OS should save and restore the state
> of the FPU between context switches.  IIRC, Windows indeed does that,

Glad to hear it, but I greatly mistrust MS.

> except in the exceptional conditions, when a program triggered an FP
> exception in the x87.  That's why I suggested, at the beginning of
> this thread, to turn on the SIGFPE generation (it is usually masked
> off by the DJGPP startup code).  The OP replied that doing so didn't
> make any difference, so it seems like this problem is not the reason
> for the different behavior.
> 
> Hans-Bernhard also mentioned the effects on the FPU precision, but I
> don't think this could be relevant unless the program in point fiddles
> with the default precision of the FPU, which I think is not the case.


-- 
Chuck F (cbfalconer AT yahoo DOT com) (cbfalconer AT worldnet DOT att DOT net)
   Available for consulting/temporary embedded and systems.
   <http://cbfalconer.home.att.net>  USE worldnet address!