void setup(){
  // put your setup code here, to run once:
  volatile char *ddra,*ddrb,*outa,*outb,ones,tens,hundred,thousand;
  ddra=0x21;outa=0x22;ddrb=0x24;outb=0x25;
  *ddra=0xff;*ddrb=0x0f;
  volatile long i,j,k;
  int display[10]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};
  while(1)
  { for(j=0;j<9999;j++)
    { 
      for(k=0;k<1;k++)
      {
        thousand=j/1000;
        hundred=(j%1000)/100;
        tens=(j%100)/10;
        ones=j%10;

        *outb=0x0e;
        *outa=display[thousand];
        for(i=0;i<10000;i++);
        *outa=0x00;

        *outb=0x0d;
        *outa=display[hundred];
        for(i=0;i<10000;i++);
        *outa=0x00;

        *outb=0x0b;
        *outa=display[tens];
        for(i=0;i<10000;i++);
        *outa=0x00;

        *outb=0x07;
        *outa=display[ones];
        for(i=0;i<10000;i++);
        *outa=0x00;
      }
      
    }
    
  }
}