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#include <..\kernel.h>
#include <..\libc\stdlib.h>
#include <..\libc\string.h>
#include <..\driver.h>

#define HZ 10000

#define CLOCK_TICK_RATE 1193180
#define TIME  ((CLOCK_TICK_RATE + HZ/2) / HZ)

static struct CoreDevice TimerDevice;

/* Sets up the system clock for fireing every 10000th of a second */
void timer_install()
{
    /* Install driver */
	memcpy(TimerDevice.Device, "pit", 4);

	/* no need to set bits just clear flags */
	TimerDevice.flags = 0;

	TimerDevice.irq = -1;
	/* IRQ is now handled by multitasking */
	TimerDevice.IrqHandler = 0;

	TimerDevice.Read = 0;
	TimerDevice.ReadEx = 0;
	TimerDevice.Control = 0;
	TimerDevice.Write = 0;
	TimerDevice.WriteEx = 0;

	RegisterCoreDevice(&TimerDevice);

	/* Set timing properties to time @ 10000Hz */

	outportb(0x43, 0x34); // binary, mode 2, LSB/MSB, ch 0
	outportb(0x40, TIME & 0xff); // LSB
	outportb(0x40, TIME >> 8); // MSB
}

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timer.c:

void hndlr_timer(void) {
	ticks++;

	if(ticks%18==0) {
	seconds++;
	}
}

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if(ticks%100==0) {
	seconds++;
	}