void init_port(void);
void outport(char);
void show_digits( void);
void delay1(int);
void outportc( char );
void delay2( void );

void setup() {
  init_port();
  show_digits();
}
;
void show_digits()
{
  int i,k;
  char ones, tens,huns, tsds;
  char digit[10] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};
  while(1)
  {
    outportc(0x00);
    for(i=0; i<10000; i++)
    {
      ones = i%10;
      tens = (i/10)%10; 
      huns = (i/100)%10;
      tsds = i/1000;

      for(k=0; k<100; k++)
      {
        outport(~digit[ones]);
        outportc(0x08);
        delay1(1);
        outportc(0x00);

        outport(~digit[tens]);
        outportc(0x04);
        delay1(1);
        outportc(0x00);

        outport(~digit[huns]);
        outportc(0x02);
        delay1(1);
        outportc(0x00);

        outport(~digit[tsds]);
        outportc(0x01);
        delay1(1);
        outportc(0x00);
      }
    }
  }
}
void init_port()
{
  char *portb_dir  = (char *)0x24;
  char *portd_dir  = (char *)0x2A;
  char *portc_dir  = (char *)0x27;
  *portb_dir = 0x0F;
  *portd_dir = 0xF0;
  *portc_dir = 0x03;
}

void outport( char out_data)
{
  char *portb_data = (char *)0x25; 
  char *portd_data = (char *)0x2B; 
  *portb_data = out_data >> 4;
  *portd_data = out_data << 4;
}

void outportc( char out_data)
{
  char *portc_data = (char *)0x28; 
  *portc_data = out_data;
}

void delay1(int count)
{
  volatile long i;
  while(count)
  {
    for(i=0; i<1000; i++);
    count--;
  }
}
void delay2( void )
{
  volatile long i;
    for(i=0; i<100; i++);
}

void loop() {

}