X-Authentication-Warning:	delorie.com: mail set sender to djgpp-bounces using -f
From:	simnav AT gmail DOT com
Newsgroups:	comp.os.msdos.djgpp
Subject:	SIGALRM and debugger
Date:	Thu, 28 Jun 2007 09:33:01 -0700
Organization:	http://groups.google.com
Lines:	60
Message-ID:	<1183048381.830011.194660@g4g2000hsf.googlegroups.com>
NNTP-Posting-Host:	88.40.73.114
Mime-Version:	1.0
X-Trace:	posting.google.com 1183048382 6178 127.0.0.1 (28 Jun 2007 16:33:02 GMT)
X-Complaints-To:	groups-abuse AT google DOT com
NNTP-Posting-Date:	Thu, 28 Jun 2007 16:33:02 +0000 (UTC)
User-Agent:	G2/1.0
X-HTTP-UserAgent:	Mozilla/5.0 (Windows; U; Windows NT 5.1; it; rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4,gzip(gfe),gzip(gfe)
Complaints-To:	groups-abuse AT google DOT com
Injection-Info:	g4g2000hsf.googlegroups.com; posting-host=88.40.73.114;
	posting-account=rJqH6A0AAADn24l60w-jp4A6NuOfth4S
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

I've set with settitimer a 50msec timer and I've installed a function
to handle SIGALRM that is correctly called every 50msec. Often a
problem occours: if I set a breakpoint in main code when I press F8 to
proceed to next instruction, software crash reporting a general
protection fault (SIGSEGV) in a location that's checked with gdb seems
to be invalid; there is no kind of problem if I don't set breakpoints.
Is this a known problem of djgpp or I did something wrong ?

Thank you.
Best regards.
Simone Navari.

Here is the code I've used (i put breakpoint if Hello printf).

#include <pc.h>
#include <stdio.h>
#include <sys/time.h>
#include <signal.h>

void f(int n)
{
  printf("+\n");
}

int main(void)
{
  void(*old)(int);

  struct itimerval timer;

  asm("sti");

  timer.it_interval.tv_sec=0;
  timer.it_interval.tv_usec=50000;
  timer.it_value.tv_sec=0;
  timer.it_value.tv_usec=2000;

  setitimer(ITIMER_REAL,&timer,NULL);

  old=signal(SIGALRM,f);

  while(1)
  {
    if(kbhit())
    {
      int c=getkey();
      if(c=='A')
      {
        printf("Hello\n");
      }
      if(c==0x0d)
      {
        break;
      }
    }
  }

  signal(SIGALRM,old);
}

- Raw text -