int keyboard_scan();
volatile char *dir,*porta,*portc,*portf,*portk;

void setup() {
  // put your setup code here, to run once:
  dir = 0x21;
  *dir = 0xff;
  dir = 0x27;
  *dir = 0xff;
  dir = 0x30;
  *dir = 0x00;
  dir = 0x107;
  *dir = 0x0f;

  porta = 0x22;
  portc = 0x28;
  portf = 0x2f;
  portk = 0x108;

  char val[] = {0x00,0x06,0x5b,0x4f,0x00,0x66,0x6d,0x7d,0x00,0x07,0x7f,0x6f,0x00,0x00,0x3f,0x00,0x00};
  char indxs[4];
  char pos,index,flag = 0;
  while(1)
  {
    index = keyboard_scan();
    if(index != 0)
    {
      indxs[flag] = index;
      flag++;
      delay(200);
    }
    
    if(flag == 4)
    {
      while(1)
      {
        for(volatile long i = 0;i < 4;i++)
        {
            *portc = ~(1 << i);
            *porta =val[indxs[i]];
            *porta = 0x00;
        }
      } 
    }
    // delay(1000);
  }     
}
 
int keyboard_scan()
{
  for(char j = 0 ;j < 4;j++)
  {
      *portk = 1 << j;
      if((*portf & 0x0f) != 0)
      {
        if((*portf  & 0x0f) == 0x01)
        return j * 4 + 1;
        else if((*portf  & 0x0f) == 0x02)
        return j * 4 + 2;
        else if((*portf  & 0x0f) == 0x04)
        return j * 4 + 3;
        else if(*portf  & 0x0f == 0x08)
        return j * 4 + 4;
      }  
  }
    return 0;
}