//initial input of the EEPROM
int first_input_0 = 0;
int first_input_1 = 0;
int first_input_2 = 0;
int first_input_3 = 0;

//pins of initial input
int pin_0 = 2; //LSB
int pin_1 = 3;
int pin_2 = 4;
int pin_3 = 5;

//pins of output of EEPROM (I region), becomes input of arduino
int eeprom_out_0 = 6;
int eeprom_out_1 = 7;
int eeprom_out_2 = 8;
int eeprom_out_3 = 9;
int eeprom_out_4 = 10;
int eeprom_out_5 = 11;
int eeprom_out_6 = 12;
int eeprom_out_7 = 13;

//output to be displayed in 7segment LED
int final_output_0 = A0;
int final_output_1 = A1;
int final_output_2 = A2;
int final_output_3 = A3;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  pinMode(pin_0, OUTPUT);
  pinMode(pin_1, OUTPUT);
  pinMode(pin_2, OUTPUT);
  pinMode(pin_3, OUTPUT);

  pinMode(eeprom_out_0, INPUT);
  pinMode(eeprom_out_1, INPUT);
  pinMode(eeprom_out_2, INPUT);
  pinMode(eeprom_out_3, INPUT);
  pinMode(eeprom_out_4, INPUT);
  pinMode(eeprom_out_5, INPUT);
  pinMode(eeprom_out_6, INPUT);
  pinMode(eeprom_out_7, INPUT);

  pinMode(final_output_0, OUTPUT);
  pinMode(final_output_1, OUTPUT);
  pinMode(final_output_2, OUTPUT);
  pinMode(final_output_3, OUTPUT);


  //SETUP 000 AS ADDRESS OF EEPROM
  digitalWrite(pin_0, LOW);
  digitalWrite(pin_1, LOW);
  digitalWrite(pin_2, LOW);
  digitalWrite(pin_3, LOW);
}

void loop() {
  Serial.println("address of eeprom");
  Serial.println(first_input_3);
  Serial.println(first_input_2);
  Serial.println(first_input_1);
  Serial.println(first_input_0);

  //i region bits coming from eeprom output
  int i_0 = digitalRead(eeprom_out_0);
  int i_1 = digitalRead(eeprom_out_1);
  int i_2 = digitalRead(eeprom_out_2);
  int i_3 = digitalRead(eeprom_out_3);
  int i_4 = digitalRead(eeprom_out_4);
  int i_5 = digitalRead(eeprom_out_5);
  int i_6 = digitalRead(eeprom_out_6);
  int i_7 = digitalRead(eeprom_out_7);

  //save operation (5 bits of i region but only 2 bits is necessary 00, 01, and 10)
  int operation_0 = i_3;
  int operation_1 = i_4;

  //address of D region
  int d_0 = i_0;
  int d_1 = i_1;
  int d_2 = i_2;
  int d_3 = 1; //constant + 8

  //supply the new address of eeprom to find the D
  digitalWrite(pin_0, d_0);
  digitalWrite(pin_1, d_1);
  digitalWrite(pin_2, d_2);
  digitalWrite(pin_3, d_3);

  //get d region bits from EEPROM
  i_0 = digitalRead(eeprom_out_0);
  i_1 = digitalRead(eeprom_out_1);
  i_2 = digitalRead(eeprom_out_2);
  i_3 = digitalRead(eeprom_out_3);
  i_4 = digitalRead(eeprom_out_4);
  i_5 = digitalRead(eeprom_out_5);
  i_6 = digitalRead(eeprom_out_6);
  i_7 = digitalRead(eeprom_out_7);

  //classify upper and lower nibble
  int upper_0 = i_4;
  int upper_1 = i_5;
  int upper_2 = i_6;
  int upper_3 = i_7;

  int lower_0 = i_0;
  int lower_1 = i_1;
  int lower_2 = i_2;
  int lower_3 = i_3;

  //output upper nibble
  if(operation_0 == 0 && operation_1 == 0){
    digitalWrite(final_output_0, upper_0);
    digitalWrite(final_output_1, upper_1);
    digitalWrite(final_output_2, upper_2);
    digitalWrite(final_output_3, upper_3);
  }
  else if(operation_0 == 1 && operation_1 == 0){
    digitalWrite(final_output_0, lower_0);
    digitalWrite(final_output_1, lower_1);
    digitalWrite(final_output_2, lower_2);
    digitalWrite(final_output_3, lower_3);
  }
  else if(operation_0 == 0 && operation_1 == 1){
    Serial.println("nasa 10");
    int sum_0 = (upper_0 + lower_0)%2;
    int carry_0 = (upper_0 + lower_0)/2;

    int sum_1 = (upper_1 + lower_1 + carry_0)%2;
    int carry_1 = (upper_1 + lower_1 + carry_0)/2;

    int sum_2 = (upper_2 + lower_2 + carry_1)%2;
    int carry_2 = (upper_2 + lower_2 + carry_1)/2;

    int sum_3 = (upper_3 + lower_3 + carry_2)%2;
    Serial.println("SUM: ");
    Serial.println(sum_3);
    Serial.println(sum_2);
    Serial.println(sum_1);
    Serial.println(sum_0);

    digitalWrite(final_output_0, sum_0);
    digitalWrite(final_output_1, sum_1);
    digitalWrite(final_output_2, sum_2);
    digitalWrite(final_output_3, sum_3);
  }

  delay(1000);

  //update the address of the I region
  first_input_0 = (first_input_0 + 1)%2;
  int input_carry_0 = (first_input_0 + 1)/2;

  first_input_1 = (first_input_1 + 1 + input_carry_0)%2;
  int input_carry_1 = (first_input_1 + 1 + input_carry_0)/2;

  first_input_2 = (first_input_2 + 1 + input_carry_1)%2;
  first_input_3 = 0;

  //supply the new address to EEPROM
  digitalWrite(pin_0, first_input_0);
  digitalWrite(pin_1, first_input_1);
  digitalWrite(pin_2, first_input_2);
  digitalWrite(pin_3, first_input_3);


}