//
//
// hello.ftdi.44.buttonecho.c
// 
//
// If the button is pressed, count time. 
// If unpressed, wait for 2 second and lights LED same amount of time you pressed the button.
// 
// Adapted from 
// Neil Gershenfeld's 'hello.ftdi.44.echo.c' (http://academy.cba.mit.edu/classes/embedded_programming/hello.ftdi.44.echo.c)
// Julia Elbert's 'hello.ftdi.44.blink.c' (fab.cba.mit.edu/classes/863.17/Harvard/people/julia-ebert/assets/week-7/hello.ftdi.44.blink.c)
// 
//
// Joonhaeng Lee / joohaenglee@gsd.harvard.edu
// 10/23/19
//
//
// (c) Massachusetts Institute of Technology 2010
// This work may be reproduced, modified, distributed,
// performed, and displayed for any purpose. Copyright is
// retained and must be preserved. The work is provided
// as is; no warranty is provided, and users accept all 
// liability.
//

#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>

#define output(directions,pin) (directions |= pin) // set port direction for output
#define input(direction,pin) (direction &= (~pin))
#define set(port,pin) (port |= pin) // set port pin
#define get(port,pin) ((port) & (pin))
#define clear(port,pin) (port &= (~pin)) // clear port pin

#define toggle(port,pin)(port ^=pin) // toggle port pin
#define pin_test(pins,pin) (pins & pin) // test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set
#define bit_delay_time 8.5 // bit delay for 115200 with overhead
#define bit_delay() _delay_us(bit_delay_time) // RS232 bit delay
#define half_bit_delay() _delay_us(bit_delay_time/2) // RS232 half bit delay
#define char_delay() _delay_ms(10) // char delay
#define led_delay() _delay_ms(500)

#define serial_port PORTA
#define serial_direction DDRA
#define serial_pins PINA
#define serial_pin_in (1 << PA0)
#define serial_pin_out (1 << PA1)

// LED
#define LED_port PORTA
#define LED_direction DDRA
#define LED_pin (1 << PA7)
uint8_t led_state = 0;
uint8_t previous_reading = 0;
uint8_t button_was_pressed = 0;
uint8_t button_pressed_length = 0;

//Button
#define button_port PORTB
#define button_pins PINB
#define button_direction DDRB
#define button_pin (1 << PB2)
#define button_interrupt (1 << PCIE1)
#define button_interrupt_pin (1 << PCINT10)

#define max_buffer 25

//this code from Julia's hello.ftdi.44.button-interrupt.c
//http://fab.cba.mit.edu/classes/863.17/Harvard/people/julia-ebert/assets/week-7/hello.ftdi.44.button-interrupt.c
ISR(TIM0_COMPA_vect) {
   //
   // Timer interrupt
   //
   if (get(button_pins, button_pin) != previous_reading) 
   {
      if (!button_was_pressed) // when you start to press button
      {
            led_state ++;
            led_state = led_state % 2;
            button_was_pressed = 1;
            button_pressed_length = 0;
      } 
      else //when you put your hand off from switch 
      {
         button_was_pressed = 0;
      }
      previous_reading = get(button_pins, button_pin);
   }
   else
   {
      if (button_was_pressed) // while butten is pressed
      {
         button_pressed_length ++;
      }
   }

   //#define max_buffer 25

void get_char(volatile unsigned char *pins, unsigned char pin, char *rxbyte) {
   //
   // read character into rxbyte on pins pin
   //    assumes line driver (inverts bits)
   //
   *rxbyte = 0;
   while (pin_test(*pins,pin));
   //
   // wait for start bit
   //
   //
   // delay to middle of first data bit
   //
   half_bit_delay();
   bit_delay();
   //
   // unrolled loop to read data bits
   //
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 0);
   else
      *rxbyte |= (0 << 0);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 1);
   else
      *rxbyte |= (0 << 1);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 2);
   else
      *rxbyte |= (0 << 2);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 3);
   else
      *rxbyte |= (0 << 3);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 4);
   else
      *rxbyte |= (0 << 4);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 5);
   else
      *rxbyte |= (0 << 5);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 6);
   else
      *rxbyte |= (0 << 6);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 7);
   else
      *rxbyte |= (0 << 7);
   //
   // wait for stop bit
   //
   bit_delay();
   half_bit_delay();
   }

void put_char(volatile unsigned char *port, unsigned char pin, char txchar) {
   //
   // send character in txchar on port pin
   //    assumes line driver (inverts bits)
   //
   // start bit
   //
   clear(*port,pin);
   bit_delay();
   //
   // unrolled loop to write data bits
   //
   if bit_test(txchar,0)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,1)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,2)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,3)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,4)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,5)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,6)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,7)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   //
   // stop bit
   //
   set(*port,pin);
   bit_delay();
   //
   // char delay
   //
   bit_delay();
   }

void put_string(volatile unsigned char *port, unsigned char pin, char *str) {
   //
   // print a null-terminated string
   //
   static int index;
   index = 0;
   do {
      put_char(port, pin, str[index]);
      ++index;
      } while (str[index] != 0);
   }

int main(void) {
   //
   // main
   //
   static char chr;
   static char buffer[max_buffer] = {0};
   static int index;
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // initialize output pins
   //
   set(serial_port, serial_pin_out);
   output(serial_direction, serial_pin_out);
   //initialize LED pin
   //
   clear(LED_port,LED_pin);
   output(LED_direction,LED_pin);

   // Set up button
   set(button_port, button_pin);
   input(button_direction, button_pin);


   // Set up timer + interrupt (for button debouncing)
   TCCR0B |= ((1 << CS02) | (1 << CS00)); // Timer 0 prescaling - divides by 1024 */
   TCCR0A |= (1 << WGM01); // Put timer 0 in CTC mode
   OCR0A = 100; // Count 100 cycles for interrupt
   TIMSK0 |= (1 << OCIE0A); // enable timer compare interrupt
   sei(); // Enable global interrupts
   //
   // main loop
   //
   index = 0;
   
   while (1) {

      if(button_was_pressed)
      {

      } 
      else 
      {
         if(button_pressed_length > 0)
         {
         set(LED_port,LED_pin);
         _delay_ms(1000);
         clear(LED_port,LED_pin);
         button_pressed_length = 0;
         }

      }

   }
   
}