void setup() {
  // put your setup code here, to run once:
volatile char *dir1;
dir1 = 0x30;
*dir1 = 0xff; 
volatile char *dir2;
dir2 = 0x107;
*dir2 = 0xff; 
volatile char *dir3;   // rows   port D
dir3 = 0x2A;
*dir3 = 0xff; 
volatile char *dir4;  //col port B
dir4 = 0x24;
*dir4 = 0x00; 
}

void loop() {
  // put your main code here, to run repeatedly:
volatile char *seg;
seg = 0x31;
volatile char *digit;
digit = 0x108;
volatile char *row;   // rows   port D
row = 0x2B;
volatile char *col;  //col port B
col = 0x23;

*digit=0x08;
volatile char x,j,k;
volatile long i;
volatile int arr[]={0x10,0x20,0x40,0x80};
volatile int arr1[]={0xf9,0xa4,0xb0,0xf0};
volatile int arr2[]={0x99,0x92,0x82,0xf0};
volatile int arr3[]={0xf8,0x80,0x90,0xf0};
volatile int arr4[]={0x10,0xf9,0x54,0xf0};
*seg = 0xff;
x = *col;
while(1){
  for(k=0;k<4;k++)
  {
    *row = 1 << k;
   if (*row == 1)
   for(j=0;j<4;j++)
    {
      x = *col;
      if((x & arr[j]) == arr[j]) 
      {*seg = arr1[j];}
    }
if (*row == 2)
   for(j=0;j<4;j++)
    {
      x = *col;
      if((x & arr[j]) == arr[j]) 
      {*seg = arr2[j];}
    }
  
 if (*row == 4) 
   for(j=0;j<4;j++)
    {
      x = *col;
      if((x & arr[j]) == arr[j]) 
      {*seg = arr3[j];}
    }
if (*row == 8)   
   for(j=0;j<4;j++)
    {
      x = *col;
      if((x & arr[j]) == arr[j]) 
      {*seg = arr4[j];}
    }
}}



}