#include <Arduino.h>

int main(void) {
  init();

  #if defined(USBCON)
    USBDevice.attach();
  #endif

  //==================== PINMODE registers (INPUT unless told otherwise)
  // 
  //  PORTA -->
  //   - A0 - SC0 - 22
  //   - A1 - BK0 - 23
  //   - A2 - SC1 - 24
  //   - A3 - BK1 - 25
  //   - A4 - SC2 - 26
  //   - A5 - BK2 - 27
  //   - A6 - SC3 - 28
  //   - A7 - BK3 - 29
  //  
  //  PORTJ --> NOTE --> The majority of the bits in the PORTJ do NOT have a pinout in the Arduino MEGA board
  //   - J6 - SC4
  //   - J5 - BK4
  //   - J4 - SC5
  //   - J3 - BK5
  //   - J2 - SC6
  //   - J1 - BK6
  //
  //  PORTC -->
  //   - C7 - SC7 - 30
  //   - C6 - BK7 - 31
  //   - C0 - DIR_485
  //
  //  PORTD -->
  //   - D3 - TX1
  //   - D2 - RX1


  DDRC = DDRC | (1 << DDC0);   //The only output register we need to control is PORTC0

  Serial.begin (9600); 
  PORTC = PORTC | (1<<PORTC0);

  uint8_t counter_A = 0;
  uint8_t free_bikes = 0;
  uint8_t free_scooters = 0;
  uint8_t counter_J = 0;
  char scooters{};
  char bikes{};

  for (;;) {    //For loop

    counter_A = 0;
    free_bikes = 0;
    free_scooters = 0;

    for(uint32_t iter = 1; iter < 0b10000001; iter = (iter << 1)) {

      if(PINA & iter) { 
        // The position we are checking is 1, so its NOT free. We do nothing.
          
        ++counter_A;
      } else {
        // The position we are checking is 0, so its FREE.

        if(counter_A % 2) {
          // If the counter is odd, the current reading is from a BIKE that is free
          ++free_bikes;

        } else {
          // If the counter is even, the current reading is from a SCOOTER that is free

          ++free_scooters;
        }

        ++counter_A;
      }
    }

    counter_J = 0;

    for(uint32_t iter = 2; iter < 0b01000001; iter = (iter << 1)) {

        if(PINJ & iter) { 
          // The position we are checking is 1, so its NOT free. We do nothing.
          
          ++counter_J;
        } else {
          // The position we are checking is 0, so its FREE.

          if(counter_J % 2) {
            // If the counter is odd, the current reading is from a BIKE that is free
            ++free_bikes;

          } else {
            // If the counter is even, the current reading is from a SCOOTER that is free
            ++free_scooters;
          }

          ++counter_J;
        }
    }

    if(!(PINC & (1<<PIN7))) { 
      //If PIN7 of PORTC is 0, it means its free (last remainding scooter stand).

      ++free_scooters;
    }

    if(!(PINC & (1<<PIN6))) { 
      //If PIN6 of PORTC is 0, it means its free (last remainding bike stand).

      ++free_bikes;
    }

    scooters = free_scooters + 48;
    bikes = free_bikes + 48;

    char message[5] = {bikes, ' ', '-', ' ', scooters}; //  '\0' --> String conversion

    Serial.println(message);
    delay (100);

    if (serialEventRun) serialEventRun();
  }

  return 0;
}