// ETALVIS PROBLEM  7 SEGMENT SET3 PROBLEM 10
// DISPLAYING 0.000 TO 999.9
void delays(void);
void setup()
{
  volatile char *porta_dir=0x21;
  *porta_dir=0xFF;
  volatile char *portb_dir=0x24;
  *portb_dir=0x0F;
}
void loop()
{
  volatile char *porta_out=0x22;
  volatile char *portb_out=0x25;
  volatile char ones,tens,hunds,thous;
  const char seven[]=
  {
    0x3F, // 0
    0x06,// 1
    0x5B,// 2
    0x4F,// 3
    0x66,// 4
    0x6D,// 5
    0x7D,// 6
    0x07,// 7
    0x7F,// 8
    0x6F // 9

  };
  char k,l;
  
 
    while(1)
    {
    for(k=0;k<3;k++)
    {
      l=0;
      if(k>l)
      {
        l=1;
      }
      for(thous=l;thous<10;thous++)
      {
        for(hunds=0;hunds<10;hunds++)
        {
          for(tens=0;tens<10;tens++)
          {
            for(ones=0;ones<10;ones++)
            {
              for(char r=0;r<30;r++) // KEEPING THE OUTPUT FOR SOME TIME
              {
                
                // DIGIT 1
                *portb_out=0x07;
                if(k==0)
                {
                  *porta_out=seven[thous]|0x80;
                  delays();
                  *porta_out=0x00;
                  *portb_out=0x0F;
                }
                else
                {
                  *porta_out=seven[thous];
                  delays();
                  *porta_out=0x00;
                  *portb_out=0x0F;
                }
                // DIGIT 2
                *portb_out=0x0B;
                if(k==1)
                {
                  *porta_out=seven[hunds]|0x80;
                  delays();
                  *porta_out=0x00;
                  *portb_out=0x0F;
                }
                else
                {
                  *porta_out=seven[hunds];
                  delays();
                  *porta_out=0x00;
                  *portb_out=0x0F;
                }
                // DIGIT 3
                *portb_out=0x0D;
                if(k==2)
                {
                  *porta_out=seven[tens]|0x80;
                  delays();
                  *porta_out=0x00;
                  *portb_out=0x0F;
                }
                else
                {
                  *porta_out=seven[tens];
                  delays();
                  *porta_out=0x00;
                  *portb_out=0x0F;
                }
                // DIGIT 4
                *portb_out=0x0E;
              
               
                  *porta_out=seven[ones];
                  delays();
                  *porta_out=0x00;
                  *portb_out=0x0F;
                
              }
            }
          }
        }
      }
    }
  }
}


void delays(void)
{
  volatile long i;
  for(i=0; i<100; i++); // small delay
}