(unknown charset) Re: [BLACKBOX] floating point arithmetic

From: (unknown charset) [at]} <Robert>
Date: Sun, 20 Jan 2008 15:20:28 +0000

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Bernhard Treutwein wrote:
> I remember vaguely that the flags are not necessarily
> preserved when a task switches. If this is true, it makes
> things even worse. Sorrily I don't remember where
> I read this. Does somebody know more?

When I change the floating point unit flags I observe the following
guidelines:

- I do it in small, self-contained routines.

- I set them back to the BlackBox default values before exitting the routine.

- I do not call framework procedures that might use / set these flags.

- I do not use LONGINTS, which use the FPU.

- Remember that routines like Strings.IntToString (now) use LONGINTs.


Exactly which BlackBox operations use/set the FPU could be useful information.

Regards

Robert.


ps - The following routine clears the FPU exception register:

PROCEDURE [code] ClearFPU 0DBH, 0E2H; (* FNCLEX Clear exceptions *)

I don't know (or have forgotten!) how to read it.

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Received on Sun Jan 20 2008 - 16:20:28 UTC