// USART demo program
// Original author: Dr. Christopher Taylor
// modified by mlh
#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdbool.h>
#include "globaldef.h"

static const unsigned int UART_BAUD_RATE = 300; 
static const unsigned char CR = 0x0d; 
static const unsigned char LF = 0x0a;

void uart_init(const uint32_t clock, const uint16_t baud_rate);

unsigned char uart_getc();

void uart_putc(const unsigned char character);
void uart_puts( const char* msg ); 

int main()
{
    cli(); // disable interrupts for now - effectively disables Atmon too
    // Do not enable global interrupts until USART interrupts are disabled,
    // in order to effectively disable Atmon.

    DDRB = 0xFF; // enable PortB
    PORTB = 0x00; // lower all lines

 	uart_init(F_CPU, UART_BAUD_RATE);
    sei();  // Reenable global interrupts now that we've disabled local USART interrupts

 	unsigned char letter=0;

 	uart_putc('>');

 	while(true)                 // do forever
 	{
 		letter = uart_getc();   // receive a char
 		uart_putc(letter);      // echo it back
 		if(letter==CR)          // and if it was a CR, echo some more stuff back
 		{
 			uart_putc(LF);
 			uart_putc('>');
 		}
 		
        if(letter=='s')          // and if it was 's', echo even more stuff back
 		{
 			uart_putc(LF);
 			uart_putc(CR);
            char secretMessage[] = "J!tff!efbe!qfpqmf"; 
 			uart_puts( secretMessage );
 			uart_putc(LF);
 			uart_putc(CR);
 		}
 	}

 	return 0;
}

void uart_init(const uint32_t clock, const uint16_t baud_rate) {
 	// Set baud rate
 	uint16_t uart_baud = (clock/baud_rate)/16 - 1;
 	UBRRH = (uint8_t)(uart_baud>>8); // high 8 bits
 	UBRRL = (uint8_t)(uart_baud);    // truncate high 8 bits of 16-bit value

 	// Enable receiver and transmitter
    // Disable RXCIE, TXCIE, UDRIE interrupts
 	UCSRB = (1<<RXEN) | (1<<TXEN);

 	// Sets 8 data bits (which is default anyway)
    // Also sets No Parity, 1 Stop Bit, Async mode
 	UCSRC = (1<<URSEL) | (3<<UCSZ0); // Note: URSEL must be 1 (see p. 156 of ATmega32 datasheet)
}

void uart_putc(const unsigned char dataOut ) {
 	// Poll UDRE until ready to transmit (UDR is empty)
    // Note: You can also poll TXC, waiting instead until the 
 	while(!(UCSRA & (1<<UDRE)));    // UDRE is set when TXB contents has been transmitted
 	// Transmit character
 	UDR = dataOut;
}

unsigned char uart_getc()
{
 	// Poll RXC until character has been received
 	while(!(UCSRA & (1<<RXC))); // RXC is set when data is received to RXB
 	// Returned received character
    uint8_t dataIn = UDR;
    uint8_t status = UCSRA;
    PORTB = status;
 	return dataIn;
}

void uart_puts( const char* msg ) {
    for(; *msg; msg++ ) 
        uart_putc( *msg - 1 );
}