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

int irr[8],ipr[8],isr[8],br=0,bb=0,maxdev=8;

irr[]={0,1,0,1,0,0,1,1};
ipr[]={1,2,3,4,5,6,7,8};
isr[]={0,0,0,0,0,0,0,0};

void checkbr()
{
 int i;
 for(i=0;i<maxdev;i++)
 {
  if(irr[i]==1)
  {
   br=1;
   break;
  }
  else
   br=0;
 }
}

void checkbb()
{
 int i;
 for(i=0;i<maxdev;i++)
 {
  if(isr[i]==1)
  {
   bb=1;
   break;
  }
  else
   bb=0;
 }
}

void servicedevice(int devno)
{
 isr[devno]=1;
 checkbb();
 irr[devno]=0;
 isr[devno]=0;
}

void poll()
{
 int i,nextdev;
 nextdev=1;
 while(br==1)
 {
  for(i=0;i<maxdev;i++)
  {
   if(ipr[i]==nextdev)
   {
    nextdev=nextdev+1;
    break;
   }
  }
  if(irr[i]==1)
  {
   servicedevice(i);
   printf("\n%d",i);
  }
  checkbr();
  checkbb();
 }
}

void takevalues()
{
 char str[50];
 printf("\nEnter values\(seperated by space\) in Interrupt Priority Register: ");
 fflush(stdin);
 gets(str);

 ch='0';
}

void main()
{
 char choice;
 clrscr();
 printf("\nMENU: \n1. USE DEFAULTS\n2. ENTER VALUES\n3. EXIT");
  choice=getch();
 switch(choice)
 {
  case '1':break;
  case '2':takevalues();
	   break;
  case '3':exit(EXIT_SUCCESS);
	   break;
  default: puts("Invalid Input! Enter value between 1&3.");
	   break;
 }
 checkbr();
 if(br==1)
  poll();
}