void setup() {
  // put your setup code here, to run once:
   volatile long i,j;
   volatile char *dirc,*dirf,*dirk,*dira,x;
   volatile char *outc,*outf,*ink,*outa;
   dirc = 0x27;dirf = 0x30; dirk = 0x107; dira = 0x21;
   outc = 0x28;outf = 0x31; ink  = 0x106; outa = 0x22;
   *dirf = 0x0F; *dirk = 0x00; *dira = 0x0F;
  while(1)
   {
     for(i=0; i<4; i++){
       *outf = 1<<i;
       *outa = *ink;
       if(*ink != 0){
         *outc = 1 << i;
         for(j=0; j<2000000; j++);
         *outc = 0;
       }
     } 

   }
}

void loop() {
  // put your main code here, to run repeatedly:

}