// Nathon Iadimarco
// Project 2
// Problem 2
// Embedded System Programming

// Defining masks required
#define BIT0_MASK 0x01 // 0000 0001 - Bit 0
#define BIT1_MASK 0x02 // 0000 0010 - Bit 1
#define BIT2_MASK 0x04 // 0000 0100 - Bit 2
#define BIT3_MASK 0x08 // 0000 1000 - Bit 3
#define BIT4_MASK 0x10 // 0001 0000 - Bit 4
#define BIT5_MASK 0x20 // 0010 0000 - Bit 5
#define INIT_MASK 0x3F // 0011 1111 - Initialization

// Defining port C
#define PORTC_MASK 0x28
#define DDRC_MASK 0x27
#define PINC_MASK 0x26

// Defining port D
#define PORTD_MASK 0x2B
#define DDRD_MASK 0x2A
#define PIND_MASK 0x29

// Defining external interrupt control
#define EICRA_MASK 0x69
#define EIMSK_MASK 0x3D

// Defining MyDelay function
void MyDelay(unsigned long mSec);

int main(void) {

  // Initialization and assignment for DDRD
  unsigned char *portD;
  portD = (unsigned char *) PORTD_MASK; //0x2B
  // Enable the pull-up resistor on PD2 using the Port D
  // Data Register (PORTD)
  *portD |= BIT2_MASK; //0x04

  // Configure external interrupt 0 to generate an interrupt request on any
  // logical change using External Interrupt Control Register A (EICRA)
  unsigned char *AT328_EICRA;
  AT328_EICRA = (unsigned char *) EICRA_MASK; //0x69
  *AT328_EICRA |= BIT0_MASK; //0x01
  *AT328_EICRA &= ~BIT1_MASK; //0x02

  // Enable external interrupt 0 using the External Interrupt Mask Register (EIMSK)
  unsigned char *AT328_EIMSK;
  AT328_EIMSK = (unsigned char *) EIMSK_MASK; //0x3D
  *AT328_EIMSK |= BIT0_MASK; //0x01

  // Initialization and assignment for DDRC
  unsigned char *portDDRC;
  portDDRC = (unsigned char *) DDRC_MASK; //0x27
  *portDDRC |= INIT_MASK; //0x3F Setting pins PC0-PC5 for output

  // portPinC and portC intialization
  unsigned char *portPinC;
  unsigned char *portC;
  portPinC = (unsigned char *) PINC_MASK; //0x26
  portC = (unsigned char *) PORTC_MASK; //0x28

  // Enable interrupts (globals enabled)
  unsigned char *ptrSREG;
  portDDRC = (unsigned char *) 0x5F;
  *portDDRC |= 0x80;

  if (*portPinC != 0x00) {
    *portC &= *portPinC;
  }
  while (1) // Loop forever
  {
      if (*portPinC == 0x20) { 
      MyDelay(1000);
      *portC |= INIT_MASK; //0x3F
      *portC &= BIT0_MASK; //0x01
      }
      if (*portPinC == 0x00) { 
        MyDelay(1000);
        *portC |= INIT_MASK; //0x3F
        *portC &= 0x01;
      }
      else {
      MyDelay(1000);
      *portC |= INIT_MASK; //0x3F
      *portC &= *portPinC * 2;
      }
    }
}

ISR(INT0_vect) {
  unsigned char *portPinD;
  portPinD = (unsigned char *) PIND_MASK; //0x29

  unsigned char *portPinC;
  unsigned char *portC;
  portPinC = (unsigned char *) PINC_MASK; //0x26
  portC = (unsigned char *) PORTC_MASK; //0x28
 
  if (*portPinD & BIT2_MASK) { //0x04
    // PD2 is high, so button is released
    // Set PB5 low using the Port B Data Register (PORTB)
  }
  else {
    // PD2 is low, so button is pressed
    // Set PB5 high using the Port B Data Register (PORTB)
    *portC &= *portPinC;
    while (!(*portPinD & BIT2_MASK)) { // 0x04
      if (*portPinC == 0x01) {
      MyDelay(1000);
      *portC |= INIT_MASK; //0x3F
      *portC &= BIT5_MASK; //0x20
      }
      MyDelay(1000);
      *portC |= INIT_MASK; //0x3F
      *portC &= *portPinC / 2;
    }
  }

}

// Define MyDelay function
void MyDelay(unsigned long mSec)
{
volatile unsigned long i;
unsigned long endT = 7 * mSec;
for (i = 0; i < endT; i++);
}