/**********
 * Polprog 2018
 * 3 clause BSD licence
 * http://polprog.net
 */
#define F_CPU 1000000

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

#include "HD44780.h"




#define DELIMETER 0x0D
#define BUFSIZE (27)

#define DERE 2
#define BEEP 3


//we need a place to keep the incoming data and an index to access it
volatile uint8_t buffer[BUFSIZE];
volatile uint8_t idx;
volatile uint8_t address;


//flag indicating that a complete number was received
volatile uint8_t process_flag = 0;

void uart_init();
void gpio_init();
void uart_print(volatile uint8_t*);

/*
 * Interrupt subroutine for UART receive interrupt.
 */
ISR(USART_RXC_vect){
	//store our character for further processing
	uint8_t c = UDR;
	if(process_flag != 0) return; //do nothing if last data was not processed yet

	//check if the character is our message delimeter
	if(c == DELIMETER){
		buffer[idx] = 0; //null terminate our string
		process_flag = 1; //flag that we need to process the data
		idx = 0; //restore index to zero for next message
		PORTB ^= 1; //debug
	}else if(idx < BUFSIZE) { //otherwise if there is space in the buffer store it
		buffer[idx] = c; //write the character to the buffer
		//UDR = c; //echo the character back
		idx++; //increment index
	}
}



void uart_init(){
	// set baudrate to 9600 (U2X enabled, 1MHz clock)
	UBRRH = 0;
	UBRRL = 12;
	// enable 2x speed mode 
	UCSRA |= (1<<U2X);
	// Enable receiver, transmitter, and receive complete interrupt
	UCSRB = (1<<RXEN)|(1<<TXEN)|(1<<RXCIE);
	// Set frame format: 8data, 2 stop bits
	UCSRC = (1<<URSEL)|(1<<USBS)|(3<<UCSZ0);
}

void gpio_init(){
	//LED on PD3
	DDRD |= (1<<DERE) | (1<<BEEP);
	PORTD |= 0xF0; //enable pullups on address selector
}

void lcd_init(){
	LCD_Initalize(); //sic
	LCD_Clear();
	
}



void uart_print(volatile uint8_t* message){
	PORTD |= (1<<DERE);	//enable tx
	while(*message != 0){
		while(!(UCSRA & (1<<UDRE)));
		UDR = *message;
		message++;
	}
	PORTD &= ~(1<<DERE); //disable tx
}

int main(){
	//initialize GPIO
	gpio_init();
	//initialize UART
	uart_init();
	//init lcd
	lcd_init();
	//initialize buffer
	for(idx = 0; idx < BUFSIZE; idx++){
		buffer[idx] = 0;
	}
	idx = 0;
	
	address = (PIND >> 4) ^ 0x0F;

	PORTD |= (1<<BEEP);
	LCD_WriteText("Address:");
	char adr[2] = {address+48, ' '};
	LCD_WriteText(adr);
	_delay_ms(2000);
	LCD_Clear();
	LCD_WriteText("Waiting for data");
	PORTD &= ~(1<<BEEP);
	
	/*_delay_ms(2000);
	LCD_Clear();
	LCD_WriteText("It's pitch black,");
	_delay_ms(2000);
	LCD_Clear();
	LCD_WriteText("You are likely to be");
	_delay_ms(2000);
	LCD_Clear();
	LCD_WriteText("eaten by a (g)rue");
	_delay_ms(2000);
	*/
	
	
	
	//enable interrupts
	sei();
	//define a variable to store the number (16 bit) and an output buffer
	uint16_t number;
	uint8_t output[BUFSIZE];
	while(1){
		while(process_flag == 0); //wait for process flag to be 1

		PORTD |= (1<<BEEP);
		LCD_Home();
		LCD_Clear();
		LCD_WriteText(buffer);

		PORTD &= ~(1<<BEEP);
		process_flag = 0;
	}

}