void setup() {
  volatile char *dirf,*dirk,*dira,*dirc;  
  
  dirf = 0x30;  dirk = 0x107; dira = 0x21; dirc = 0x27;
 *dirf = 0x0f; *dirk = 0x00; *dira = 0xff; *dirc = 0x0f;
}
void loop(){
  display_4();
}
void display_4(){
  volatile char *outf,*outa,*outc,*ink,x;
  volatile int i,num ,count,total;
  outf = 0x31;ink = 0x106; outc = 0x28;outa = 0x22; 
  volatile char numbers[]={0xC0,0xF9,0xA4,0xB0,0X99,0X92,0X82,0xF8,0x80,0x90};
  count = 0;
  total = 0;
  while(1){
    for(i=0;i<4;i++){
      *outf=1 << i;
      x=*ink;
      if(x!=0){//checks if any switch is pressed on keypad
        if(*outf==1 && x == 1){//row 1 column 1 (1)
          num = 1;
          count+=1;
        }
        if(*outf==1 && x == 2){//row 1 column 2 (2)
          num = 2;
          count+=1;
        }
        if(*outf==1 && x == 4){//row 1 column 3 (3)
          num = 3;
          count+=1;
        }
        if(*outf==2 && x == 1){// row 2 column 1 (4)
          num = 4;
          count+=1;
        }
        if(*outf==2 && x == 2){// row 2 column 2 (5)
          num = 5;
          count+=1;
        }
        if(*outf==2 && x == 4){// row 2 column 3 (6)
          num = 6;
          count+=1;
        }
        if(*outf==4 && x == 1){// row 3 column 1 (7)
          num = 7;
          count+=1;
        }
        if(*outf==4 && x == 2){// row 3 column 2 (8)
          num = 8;
          count+=1;
        }
        if(*outf==4 && x == 4){// row 3 column 3 (9)
          num = 9;
          count+=1;
        }
        if(*outf==8 && x == 2){// row 4 column 2 (0)
          num = 0;
          count+=1;
        }
        *outc=0x01;
        *outa=numbers[num];
        delay(200);
        total = (total*10) + num; 
      }
    }
    if(count == 4){
      int thousand,hundred,ten,one;
      thousand = (total/1000);
      hundred = ((total/100)%10);
      ten = ((total/10)%10);
      one = (total%10);
      //display 1st digit entered
      *outc = 1;
      *outa = numbers[thousand];
      delay(500);
      //display 2nd digit entered
      *outc = 2;
      *outa = numbers[hundred];
      delay(500);
      //display 3rd digit entered
      *outc = 4;
      *outa = numbers[ten];
      delay(500);
      //display 4th digit entered
      *outc = 8;
      *outa = numbers[one];
      delay(2000);
      //reset count back to 0 and display to nothing
      count = 0;
      total = 0;
      *outc = 0x08;
      *outa = 0x00;
    }
  }
}