int aanstaanden = 0;
bool firstLoop = true;
long time = 0;
long prevTime = 0;

// pinout:
// D6 through D13 -- data lines
// A0 through A2 -- WE, OE, CE respectively
// D2 up to D6 -- control pins for the shift registers

// Main function
void loop()
{
  time = millis();
  if(firstLoop)
  {
    write_a_byte(1, 1);
    firstLoop = false;
  }
  else if(time - prevTime > 5000)
  {
    Serial.print("The following EEPROM value has been found: ");
    Serial.print(read_a_byte(1));
    prevTime = time;
  }

}


uint8_t read_a_byte(uint16_t address) {


  io_input();
  turn_on(OE);
  turn_off(CE);
  turn_on(WE);

  put_adresses(address);
  turn_off(OE);
  delayMicroseconds(10);
  byte data = read_io();
  turn_on(OE);
  turn_on(CE);
}

void write_a_byte(uint8_t data, uint16_t address) {

  turn_on(CE);
  turn_on(OE);
  turn_on(WE);
  delay(100);

  put_adresses(address);
  put_io(data);
  turn_off(CE);
  turn_off(WE);
  // Time to latch address
  delayMicroseconds(15);
  turn_on(WE);
  // Time to latch data
  delayMicroseconds(15);
  turn_on(CE);
  delay(1);
// NOTE this bit is commented out in my code, as this will result in an infinite wait since the write function
// isn't working, so it always reads back 255
  uint8_t done = 0;
  while(done != 1)
 {
   if(read_a_byte(address) == data)
   {
        done = 1;
   }
   else
  {
   delay(1);
  }
 }
  turn_adresses_off();
}


void turn_on(uint8_t port)
{
  digitalWrite(port, HIGH);
}
void turn_off(uint8_t port)
{
  digitalWrite(port, LOW);
}


void put_adresses(uint16_t address)
{

  for(uint16_t i = 0; i < 16; i++)
  {
    if((1 << i) & address)
    {
      aanstaanden |= (1 << i);
    }
    else
    {
      aanstaanden &= ~(1 << i);
    }
  }
  shift_a_byte(aanstaanden);


}

void turn_addresses_off()
{
    for(uint16_t i = 0; i < 16; i++)
  {
    aanstaanden &= ~(1 << i);
  }

  shift_a_byte(aanstaanden);
}

void put_io(int val)
{

  for(int i = 0; i < 8; i++)
  {
    if((1 << i) & val)
    {
      // The io-lines start at digital pin 6 and run up to and including digital pin 13
      digitalWrite(6 + i, HIGH);
    }
    else
    {
      digitalWrite(6 + i, LOW);
    }
  }


}

byte read_io()
{
        byte b = 0;
        for(int i = 0; i < 8; i++)
        {
                if(digitalRead(6 + i) == HIGH)
                {
                        b |= (1 << i);
                }
        }
        return b;
}

void io_input()
{

  pinMode(io_1, INPUT);
  pinMode(io_2, INPUT);
  pinMode(io_3, INPUT);
  pinMode(io_4, INPUT);
  pinMode(io_5, INPUT);
  pinMode(io_6, INPUT);
  pinMode(io_7, INPUT);
  pinMode(io_8, INPUT);

}

// Yes, these pins are all mapped correctly and tested with a volt meter!
void shift_a_byte(int b)
{
  digitalWrite(clk, LOW);
  digitalWrite(srclk, LOW);
  for(int i = 16; i >= 0; i--)
  {
    if((1 << i) & b)
    {
      digitalWrite(serial_out, HIGH);
    }
    else
    {
      digitalWrite(serial_out, LOW);
    }

    digitalWrite(srclk, HIGH);
    digitalWrite(srclk, LOW);
  }

  digitalWrite(clk, HIGH);
}