// Brandon Jennings
// Embedded Systems Project 2 Problem 1.1


// Forward declaration for MyDelay function
void MyDelay(unsigned long mSec);

int main(void) {
  //unsigned char *ptrSREG;
  //ptrSREG = (unsigned char *) 0x5F; // AVR Status Register
  //*ptrSREG &= ~(0x80); // 0xxx xxxx // Global Interrupt Disable
  // How to disable global interrupt without breaking?

  unsigned char *portD;
  portD = (unsigned char *) 0x2B; // Data Register (Port D)
  *portD |= 0x04; // 0000 0100 (PD2 ON)

  unsigned char *AT328_EICRA;
  AT328_EICRA = (unsigned char *) 0x69; // External Interrupt Control Register A
  *AT328_EICRA |= 0x01; // Interrupt on any logical change
  *AT328_EICRA &= ~(0x02); // Turns off xx0x (prevents register from being in wrong setting)

  unsigned char *AT328_EIMSK;
  AT328_EIMSK = (unsigned char *) 0x3D; // External Interrupt Mask Register
  *AT328_EIMSK |= 0x01;

  unsigned char *portDDRC;
  portDDRC = (unsigned char *) 0x27; // Data Register (PORTC)
  *portDDRC |= 0x3F; // 0011 1111 (Turning on all ports A0 - A5)

  unsigned char *ptrSREG;
  ptrSREG = (unsigned char *) 0x5F; // AVR Status Register
  *ptrSREG |= 0x80; // 1000 0000 // Global Interrupt Enable
  
  while (1) { // Regular Proccess
    unsigned char *portC;
    portC = (unsigned char *) 0x28; // Port D Output (PORTC)

    *portC &= ~0x3F; // Set PC 0-5 low
    *portC |= 0x01; // 0000 0001 (ON/High)
    MyDelay(500); // 500 seems to be about 1 second, the delay function is imprecise

    *portC &= ~0x3F;
    *portC |= 0x02; 
    MyDelay(500);

    *portC &= ~0x3F;
    *portC |= 0x04;
    MyDelay(500);

    *portC &= ~0x3F;
    *portC |= 0x08;
    MyDelay(500);

    *portC &= ~0x3F;
    *portC |= 0x10;
    MyDelay(500);

    *portC &= ~0x3F;
    *portC |= 0x20;
    MyDelay(500);
  }
}

ISR(INT0_vect) // Interrupt Service Routine
{
  unsigned char *portPinD;
  portPinD = (unsigned char *) 0x29; // Port D Input
  unsigned char *portC;
  portC = (unsigned char *) 0x28; // Port D Output (PORTC)

  // Read PD2 using the Port D Pin Input Register (PIND)
  if (*portPinD & 0x04) // 0000 0100 (???)
  {
    // PD2 is high, so button is released
    // Set PC0 low using the Port C Data Register (PORTC)
    *portC |= 0x3F; // 0001 1111 (Set PC 0-5 HIGH)
    MyDelay(2000); // Wait
  }
  else
  {
    // PD2 is low, so button is pressed
    *portC &= ~0x3F; // Set PC 0-5 LOW
    MyDelay(2000); // Wait
  }
}

// Define MyDelay function
void MyDelay(unsigned long mSec)
{
  volatile unsigned long i;
  unsigned long endT = 1000 * mSec;
  for (i = 0; i < endT; i++);
}