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From: ahenric AT ccii DOT co DOT za (Arne)
Newsgroups: comp.os.msdos.djgpp
Subject: Speeding up timer
Date: 13 Oct 2003 07:06:43 -0700
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To: djgpp AT delorie DOT com
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How can I speed up the timer so that my signal handler (on SIGALRM) is
called more often than the default 18.2Hz?

I have tried to reprogram the 8254 PIT, but that doesn't do anything.
Here is my code:

/* timer struct */
struct itimerval timeout;

void tickSignal()
{
  counter++;
}

/* set tick interrupt to 200Hz */
outportb(0x43, 0x36);
outportb(0x40, ((1193180L / 200) & 0x00ff));
outportb(0x40, (((1193180L / 200) >> 8) & 0x00ff));


/* Initialise timer structure */
timeout.it_interval.tv_sec = 0;
timeout.it_interval.tv_usec = 5000;
timeout.it_value.tv_sec = 0;
timeout.it_value.tv_usec = 5000;

__djgpp_clock_tick_interval = 5000;

signal(SIGALRM, tickSignal);
setitimer(ITIMER_REAL, &timeout, NULL);

Thanks
Arne