/*
 * UART.c
 *
 * Created: 25/11/2021 16:26:10
 *  Author: n0x
 */ 

#include "UART.h"

#define SIZE_BUFFER 500
struct CircularBuffer{
	volatile char data[SIZE_BUFFER];
	volatile uint16_t Readpointer;
	volatile uint16_t Writepointer;
};

struct CircularBuffer TxBuffer;
struct CircularBuffer RxBuffer;
volatile uint8_t TxActive;

void 
uart_init(void)
{
	UBRR0 = 103;					/* set BAUD rate to 9600 */
	 
	UCSR0C |= 
	(0<<UMSEL00)|(0<<UMSEL01)|		/* Async UART */
	(0<<UPM00)|(0<<UPM01)|			/* Disable Parity */
	(1<<UCSZ00)|(1<<UCSZ01)|		/* 8 Bit */
	(0<<USBS0);						/* 1 Stopbit */
	 	
	
	UCSR0B |= 
	(1<<TXEN0)|(1<<RXEN0)|			/* enable send and receive */
	(1<<RXCIE0);					/* enable Receive interrupts */	
	
	TxBuffer.Readpointer = 0;
	TxBuffer.Writepointer = 0;
	RxBuffer.Readpointer = 0;
	RxBuffer.Writepointer = 0;
}

/* ------------------------ */
/*       Sending Data       */
/* ------------------------ */

void
uart_send_string(char* string)
{
	int i = 0;
	while(string[i] != '\0'){
		uart_send_byte(string[i]);
		i++;
	}
}

void
uart_send_byte(char c)
{
	UCSR0B&=~(1<<TXCIE0);
	
	if(TxActive){
		TxBuffer.data[TxBuffer.Writepointer++] = c;
		if (TxBuffer.Writepointer>=SIZE_BUFFER){
			TxBuffer.Writepointer = 0;
		}
	} else {
		TxActive = 1;
		UDR0 = c;	
	}
	UCSR0B |= (1<<TXCIE0);
}

ISR(USART0_TX_vect)
{	
	if(TxBuffer.Readpointer != TxBuffer.Writepointer)
	{
		UDR0 = TxBuffer.data[TxBuffer.Readpointer++];
		
		if(TxBuffer.Readpointer >= SIZE_BUFFER){
			TxBuffer.Readpointer = 0;
		}
	} else {
		TxActive = 0;
	}
}

/* ------------------------ */
/*      Receiving Data      */
/* ------------------------ */

uint8_t 
uart_data_available(void) 
{
	uint8_t dataAvailabel = 0;
	UCSR0B &= ~(1<<RXCIE0);
	if(RxBuffer.Readpointer != RxBuffer.Writepointer){
		dataAvailabel = 1;
	}
	UCSR0B |= (1<<RXCIE0);
	return dataAvailabel;
}

char 
uart_get_data(void)
{
	char data = 0;
	UCSR0B &= ~(1<<RXCIE0);
	if(RxBuffer.Readpointer != RxBuffer.Writepointer)
	{
		data = RxBuffer.data[RxBuffer.Readpointer++];
		if(RxBuffer.Readpointer >= SIZE_BUFFER){
			RxBuffer.Readpointer = 0;
		}
	}
	UCSR0B |= (1<<RXCIE0);
	return data;
}

ISR(USART0_RX_vect)
{
	uint8_t status = UCSR0A;
	uint8_t data = UDR0;
	
	if((status & ((1<<DOR0) | (1>>FE0))) == 0){
		RxBuffer.data[RxBuffer.Writepointer++] = data;
		if(RxBuffer.Writepointer >= SIZE_BUFFER) {
			RxBuffer.Writepointer = 0;
		}
	}
}