#include <avr/io.h>
#include <avr/interrupt.h>

#ifndef F_CPU
//define cpu clock speed if not defined
#define F_CPU 8000000
#endif

//set desired baud rate

#define BAUDRATE 9600

//calculate UBRR value

#define UBRRVAL ((F_CPU/(BAUDRATE*16UL))-1)

#include <util/delay.h>
//int out_temp;
//out_temp=0;
int num595;




void
lockdata (void)
{
  PORTB &= ~(1 << PB0);
  _delay_us (1);
  PORTB |= 1 << PB0;
  _delay_us (1);
}

void
loopback595 (void)
{
  if (PINC & 1)
    PORTB |= 1 << PB3;
  else
    PORTB &= ~(1 << PB3);
  PORTB |= (1 << PB5);
  _delay_us (1);
  PORTB &= ~(1 << PB5);
  _delay_us (1);
}

int
writebit595 (int data)
{
  if (data & 1)
    PORTB |= 1 << PB3;
  else
    PORTB &= ~(1 << PB3);
  _delay_us (1);
  PORTB |= (1 << PB5);
  _delay_us (1);
  PORTB &= ~(1 << PB5);
  _delay_us (1);
  //lockdata();
  return PINC & 1;
}

int
writeBit595 (int data)
{
  int i, result;
  result = 0;
  for (i = 0; i < 8; i++)
    {
      result = result << 1;
      result += writebit595 ((data >> i) & 1);
    }
  //result=result/2;
  //PORTC=result;
  //lockdata();
  return result & 0xff;
}

int
count_595port (void)
{
  int result;
  result = 0;
  while (!(writeBit595 (0xaa) == 0xaa))
    {
      result++;
    }
  return result;
}

void
clear595 (void)
{
  int i;
  if (num595 != 0)
    {
      for (i = 0; i < num595; i++)
	writeBit595 (0);
    }
  else
    {
      count_595port ();
      for (i = 0; i < num595; i++)
	writeBit595 (0);
    }
}



ISR (SIG_UART_RECV)
{

  uint8_t Temp;

  while (!(UCSRA & (1 << RXC)))
    {
    };

  Temp = UDR;

  int i;
  PORTC = Temp;
  if (Temp == 0xff)
    {
      for (i = 0; i < (num595 * 8); i++)
	{
	  writebit595 (1);
	}
    }
  else if (Temp == 0)
    clear595 ();
  else
    {
      for (i = 1; i < (num595 * 8 + 1); i++)
	{
	  if (i == (Temp >> 1))
	    writebit595 (Temp & 1);
	  else
	    loopback595 ();
	}
    }
  lockdata ();

  //while (!(UCSRA&(1<<UDRE))){};
  //      if(UCSRA&(1<<UDRE))
  //send received data back

  //              UDR=Temp;

}

void
init (void)
{
//Set baud rate

  UBRRL = UBRRVAL;		//low byte

  UBRRH = (UBRRVAL >> 8);	//high byte


  UCSRC = (1 << URSEL) | (0 << UMSEL) | (0 << UPM1) | (0 << UPM0) |
    (0 << USBS) | (0 << UCSZ2) | (1 << UCSZ1) | (1 << UCSZ0);


  UCSRB = (1 << RXCIE) | (0 << TXCIE) | (1 << RXEN) | (1 << TXEN);
  sei ();
}

int
main (void)
{
  DDRB = 0xff;
  PORTB = 0x01;
  DDRC = 0xfe;
  num595 = 0;
  num595 = count_595port ();
  PORTC = num595 << 1;
  clear595 ();

  init ();

  int n;
  n = 0;
  while (1);

  return 0;

}