From: Erik Rull <erik_rull AT bluewin DOT de>
Newsgroups: comp.os.msdos.djgpp
Subject: Problems with protected_mode_int
Date: Tue, 11 Jan 2000 22:45:16 +0100
Organization: tesion Communikationsnetze Suedwest GmBH & Co.KG, Stuttgart, Germany
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Hi,

I've tried something with the protected_mode_int, which makes my system
crash everytime. First I wrote a programm that increases a timer
variable when the timer-int occurs. Then I inserted a system() call that
calls another
programm, with the active timer-int. But during the call, the system
crashes.
Can you help me to fix this problem?

To make it easier for you, I'll add the sources of the programms to this
mail.
Thanks for helping me!

The programm that contains the system() call:

#include <pc.h>
#include <dpmi.h>
#include <stdio.h>

     volatile int tics = 0;

     void timer_handler()
     {
       printf("Tics passed: %d\n",++tics);
     }

     int main()
     {
       _go32_dpmi_seginfo old_handler, new_handler;

       printf("grabbing timer interrupt\n");
       _go32_dpmi_get_protected_mode_interrupt_vector(8, &old_handler);

       new_handler.pm_offset = (int) timer_handler;
       new_handler.pm_selector = _go32_my_ss();
       _go32_dpmi_chain_protected_mode_interrupt_vector(8,
&new_handler);

       getkey();
       system("timer3.exe");

       printf("releasing timer interrupt\n");
       _go32_dpmi_set_protected_mode_interrupt_vector(8, &old_handler);
       printf("Time : %d",tics);

       return 0;
     }

The programm called by system():

#include <stdio.h>

main()
{
        printf("Timer3.exe is running!\n");
}

P.S. I'm still using version 2.6.3 (1.12 maint3), because no other
works...