Message-Id:	<199602291105.GAA27188@delorie.com>
From:	Emmanuel Bigler <bigler AT lpmo DOT univ-fcomte DOT fr>
Subject:	a test program to trap floating exceptions w DJGPP v.2.
To:	djgpp AT delorie DOT com
Date:	Thu, 29 Feb 1996 12:09:22 +0100 (MET)
Mime-Version:	1.0

I'm trying to use the signal() routine of DJGPP v.2 to trap floating
point exceptions, and until now I have not been sucessful getting a
prog that does not hang the machine. Apparently, the exception routine
is never reached. But I am not sure I'm using the signal() properly
since I'm more a FORTRAN guy, however I tested the same prog under a
true UNIX (HPUX), and there div by 0 and log(0) are handled
separetely, whereas raise(SIGFPE) correctly goes to the routine
exception.

This is a short summary/prog and what happens


-Emmanuel



Emmanuel BIGLER         
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--------------------------------------------------
# exceptions and signal test program  t.c
# for DJGPP v. 2 / DOS (gcc 2.7.2)
# compiled without optimization :
# gcc -s -o t t.c  -lm 
#
#include <stdio.h>
#include <signal.h>
#include <math.h>

void exception(int j)
{
printf("exception..!") ;
exit();
}

double one=1, zero=0;

main()
{
double res;
/*signal(SIGFPE, exception);*/ /* this line hangs ; hard reboot
                                  requested*/

signal(SIGFPE, SIG_IGN);       /* this one also (nope..) */

/* raise(SIGFPE); */           /* this one *alone* works and exits 
                                  even if there is no signal call
                                  before ; with a signal call before,
                                  the prog hangs and never reaches
                                  this line  */ 
res = one/zero;
res = log(zero);
return res=-1.0;
}

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