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From: evans@syd.dit.CSIRO.AU (Bruce.Evans)
Newsgroups: comp.os.minix
Subject: Re: A question about floating-point with ACK
Message-ID: <1991Jun6.024550.15097@syd.dit.CSIRO.AU>
Date: 6 Jun 91 02:45:50 GMT
References: <1991Jun5.205138.2909@viewlogic.com>
Organization: CSIRO Division of Info Tech, Sydney, Australia
Lines: 33

In article <1991Jun5.205138.2909@viewlogic.com> greg@suntan.viewlogic.com (Gregory Larkin) writes:

>I am using Peter Housel's floating point package installed in
>...
>I recently acquired the latest version of the "Enquire" program.
>...
>"Floating pt. overflow" is displayed.  The program is using
>the signal() call to trap overflows (I think, I don't a lot about
>...
>Does the FP package just exit upon overflow instead of sending a
>SIGFPE?  Could someone enlighten me on this chain of events upon

Yes, it just exits, and this is not useful. I fixed it by replacing
the library .fat and .trpilin by

	.define .trpilin
	.define .fat
.fat:
.trpilin:
	sub	ax,ax		| zero
	div	ax		| divide by 0 to generate SIGFPE
	j	.trpilin	| repeat

This made enquire work well enough to debug the FP package further 8-).
It had a couple of minor rounding bugs.

However, this is not quite right using ACK (I actually used a modified
version with gcc) because the ACK library uses .fat and .trp for other
purposes. So, rename these functions .gensigfpe everywhere they are
called in the FP package. There may be further things to change if the
ACK compiler generates them for other FP errors.
-- 
Bruce Evans		evans@syd.dit.csiro.au