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#pragma inline;

#include <bios.h>
#include <dos.h>
#include <io.h>
#include <stdio.h>
#include <stdlib.h>

#define FALSE 0
#define TRUE 1

void interrupt (*old_int0B)(void);

static unsigned int fval;

unsigned long results[1000], head = 0, tail = 0;

extern void LZTimerOn();
extern void LZTimerOff();
extern unsigned long LZTimerCount();

int timer_on;

void interrupt msr_handler(void)
{
	static unsigned int tmr_count = 0, old_tmr_count = 0;
	static unsigned int half1, half2, count = 0;

	while(1) {
		if(inportb(0x2fa) & 1)			/* Check pending int. */
			break;
		if(! (inportb(0x2fe) & 2))		/* Check for DDSR */
			continue;

		outportb(0x43, 0x80);			/* Latch timer 2 */
		tmr_count = inportb(0x42);
		tmr_count |= (inportb(0x42) << 8);

		half2 = (unsigned int)(old_tmr_count - tmr_count);
		fval = half1 + half2;
		half1 = half2;
		old_tmr_count = tmr_count;

		if((fval >= 1193180/1300) && (fval <= 1193180/1100)) {
			if(timer_on) {
				LZTimerOff();
				timer_on = FALSE;
				results[head++] = LZTimerCount();
				if(head == 1000) head = 0;
			}
		} else {
			if(! timer_on) {
				LZTimerOn();
				timer_on = TRUE;
			}
		}
	}

	outportb(0x20, 0x20);
}



void init(void)
{
	old_int0B = getvect(0x0b);
	setvect(0x0b, msr_handler);

	asm cli;

	outportb(0x2f9, 8);    			/* Enable MS interrupt */
	outportb(0x2fc, inportb(0x2fc) | 8);	/* Activate tri-state gate */
	outportb(0x21, inportb(0x21) & 0xf7);	/* Enable IRQ3 in PIC */

	while(1) {
		inportb(0x2f8);			/* Reset RBR */
		inportb(0x2fa);			/* Reset IIR */
		inportb(0x2fd);			/* Reset LSR */
		inportb(0x2fe);			/* Reset MSR */
		if(inportb(0x2fa) & 1)		/* Loop until no pending int */
			break;
	}

	outportb(0x61, inportb(0x61) | 1);	/* Set timer 2 gate high */
	outportb(0x43, 0xB4);			/* Put timer 2 in mode 2 */
	outportb(0x42, 0x00);
	outportb(0x42, 0x00);

	asm sti;
}



void quit(void)
{
	asm cli;
	outportb(0x21, inportb(0x21) | 8);	 /* Restore int. mask */

	setvect(0x0B, old_int0B);

	asm cli;
	outportb(0x61, inportb(0x61) & 0xfe);	/* Reset timer 2 gate */
	asm sti;
	exit(0);
}




void main(void)
{
	int c;

	init();

	LZTimerOn();
	timer_on = TRUE;

	while (1) {
		if(head != tail) {
			printf("%06lu  ", results[tail++]);
			if(tail == 1000) tail = 0;
		}

		if(kbhit()) {
			getch();
			break;
		}
	}

	quit();
}
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