/*
 * uart.c
 *
 * Created: 20.02.2019 20:50:13
 *  Author: jens
 */ 

#include <stdio.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include "uart.h"
#include "message.h"

static Fifo *g_pFifo = NULL;
ISR(USART_UDRE_vect)
{
	
}

ISR(USART_TX_vect)
{
	
}

ISR(USART_RX_vect)
{
	uint8_t status = UCSR0A;
	if (status & (1 << RXC0))
	{
		uint8_t rx_data = UDR0;
		Msg_t msg =
		{
			.code = Uart,
			.m.uart.data = rx_data
		};
		fifo_push(g_pFifo, &msg);
	}
}

void uart_init(Fifo *pFifo, uint32_t baudrate)
{
	g_pFifo = pFifo;

	uint32_t prescale8 = UART_PRESCALE(baudrate, 8UL);
	uint32_t prescale16 = UART_PRESCALE(baudrate, 16UL);
	
	uint32_t fcpu8 = (prescale8 * baudrate * 8);
	uint32_t fcpu16 = (prescale16 * baudrate * 16);
	
	uint32_t err8 = abs(fcpu8 - F_CPU);
	uint32_t err16 = abs(fcpu16 - F_CPU);
	
	uint16_t prescale = prescale16;
	if (err8 < err16)
	{
		prescale = prescale8;
		
		// Double UART speed
		UCSR0A |= 1 << U2X0;
	}
	
	// Set baud rate
	uint16_t reg = prescale - 1;
	UBRR0L  = (uint8_t)reg;
	UBRR0H = (uint8_t)(reg >> 8);
	
	// Enable receiver and transmitter
	UCSR0B = (1<<TXEN0)|(1<<RXEN0);
	
	// Enable RX interrupt
	UCSR0B |= (1<<RXCIE0);
	
}

void uart_putc(char c)
{
	while((UCSR0A & (1<<UDRE0)) == 0)
	{
	}
	UDR0 = c;
}

int uart_putchar(char c, FILE *stream)
{
	uart_putc(c);
	if (c == 0x0A)
	{
		uart_putc(0x0D);
	}
	return 0;
}

void uart_puts(char const *str)
{
	while(*str)
	{
		char c = *(str++);
		uart_putc(c);
		if (c == 0x0A)
		{
			uart_putc(0x0D);
		}
	}
}