From owner-freebsd-hackers  Fri Dec 24  2:49:48 1999
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From: Sheldon Hearn <sheldonh@uunet.co.za>
To: Ben Smithurst <ben@scientia.demon.co.uk>
Cc: Bosko Milekic <bmilekic@dsuper.net>, hackers@FreeBSD.ORG
Subject: Re: SIGFPE on arithmetic overflow 
In-reply-to: Your message of "Fri, 24 Dec 1999 10:37:35 GMT."
             <19991224103735.A649@strontium.scientia.demon.co.uk> 
Date: Fri, 24 Dec 1999 12:51:23 +0200
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On Fri, 24 Dec 1999 10:37:35 GMT, Ben Smithurst wrote:

> >   Could somebody try this piece of code on a -STABLE machine, just out of
> >   curiosity...?
> 
> I did, it gets SIGFPE too.

I think this boils down to my lack of understanding of IEEE floating
point arithmetic standards.

The following code behaves the same on every box I can find to test it
on.  Although I'm surprised that the exception is INV instead of OFL, it
seems to be standard behaviour.

Ciao,
Sheldon.

#include <ieeefp.h>
#include <stdio.h>

void
do_weird(void)
{
	double	x;
	int	i;

	printf("double x = 1e19; int i = (int)x\n");
	x = 1e19;
	i = (int)x;
	printf("%d\n", i);
}

int
main(void)
{

	printf("clearing fp exception mask\n");
	(void)fpsetmask(0);
	do_weird();
	printf("setting fp exception mask to FP_X_OFL\n");
	(void)fpsetmask(FP_X_OFL);
	do_weird();
	printf("setting fp exception mask to FP_X_INV\n");
	(void)fpsetmask(FP_X_INV);
	do_weird();

	return 0;
}


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