/*
  FILE: MAX158GG.C
  DESC:	WIRED UP 7414 TO MAX158 PIN 13 (/INT)
  NOTE: MAX158 data sheet says that /INT goes low when conversion is
	complete.  /INT is inverted by the 7414 thus going high.  This
	high signal feeds into IRQ3.
*/

#include<stdio.h>
#include<dos.h>
#include<stdlib.h>
#include<conio.h>

void interrupt (*bookmarkedIrq)(void);
void interrupt doTask(void);

/* int   readData;
float outputVoltage;
float timePastInSeconds; */

int   i = 0;
long  j = 0;
int   EOC;

#define VREF  2.5
#define baseAddress 608   /* shorting block on row 4 of 74138 */
#define desiredChannel 0  /* function generator on AIN1 */
#define TRUE 1
#define FALSE 0

int main(void)
{
  EOC = FALSE; /* set MAX158 end-of-conversion to false */

  window(5,5,50,75);
  clrscr();
  gotoxy(1,3);
  cprintf("Do-while loop iteration #");

  bookmarkedIrq = getvect(irq3); /* save the old interrupt vector */
  setvect(irq3, doTask); /* install the new interrupt handler */

  /* Unmask (i.e. enable) IRQ3.  This requires turning bit 3 to 0 */
  /* and bits 0,1,2,4,5,6,7 to 1.  Hence 11110111 binary = F7 hex */

  outportb(0x21, ( inportb(0x21) & 0xF7 ) );  /* Unmask (Enable) IRQ3 */

  do {
     j++;
     gotoxy(27,3); cprintf("%ld\n", j);
     outportb(baseAddress, desiredChannel);
     while(!EOC) { /* do nothing */ };
     /* MAX158 pin 13 triggered hardware intertupt and sets EOC to TRUE */
     /* Can now acquire data */
     readData = inportb(baseAddress);
     gotoxy(32,3); cprintf("i = %d\n", i);
     gotoxy(39,3); cprintf("readData = %d\n", readData); */
     EOC = FALSE; /* reset end-of-conversion to false */
  } while(!kbhit());

  /* reset interrupt back to original */
  setvect(irq3, bookmarkedIrq);
  outportb(0x21, (inportb(0x21) | 0x08) );
  printf("bye!\n");
  return 0;

} /* end of main */

/* this ISR should execute each time IRQ3 is triggered */
void interrupt doTask(void)
{
  /* disable(); */
  #pragma asm pushf;
  #pragma asm cli;
  i++;
  EOC = TRUE; /* tell main() that MAX158 generated interrupt */
  outportb(0x20, 0x20); /* send EOI signal */
  /* enable(); */
  #pragma asm popf;
  return;
} /* end of doTask */