#define DicePort  PORTC
#define DicePortDDR  DDRC
 
#define CntrlPortDDR  DDRE
#define CntrlPort  PORTE
#define CntrlPin  PINE
 
#define Dice1CntrlPin  0
#define Dice2CntrlPin  1
#define RollCntrlPin  2
 
 
#define F_CPU    4000000UL
 
#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
 
unsigned char seed = 0;
 

unsigned char digit_to_7segval(unsigned char digit);
void roll_dice(unsigned char times);
void init();
ISR(TIMER0_OVF_vect);
 
 
int main(void)
{  
  unsigned char digit = 6;
  unsigned char digit2 = 6;
 
  init();  
 
    
  while(1)
  {
 
    if(!(CntrlPin & (1<<RollCntrlPin)))
    {
      
      CntrlPort = ~(1<<Dice1CntrlPin | 1<<Dice2CntrlPin);
      roll_dice(2);
 
      
      seed = (seed*17)+21;
      digit = seed % 6;
      digit++;
 
      seed = (seed*17);
      digit2 = seed % 6;
      digit2++; 
    }
 
    
    CntrlPort = ~(1<<Dice1CntrlPin);
    DicePort = digit_to_7segval(digit);
    _delay_ms(10);
    CntrlPort = ~(1<<Dice2CntrlPin);
    DicePort = digit_to_7segval(digit2);
    _delay_ms(10);  
  }    
 
}
 

void init()
{
  
  DicePortDDR = 0xFF;
 
  
  CntrlPortDDR = ~(1<<RollCntrlPin);

  CntrlPort = 1<<RollCntrlPin;
 
  TCCR0 = 1<<CS00;   
  TIMSK = 1<<TOIE0;   
  sei();      
}  
 

unsigned char digit_to_7segval(unsigned char digit)
{
  unsigned char segval = '0';
 
  if(digit == 1)
    segval = 0x06;    
  else if (digit == 2)
    segval = 0x5B;    
  else if (digit == 3)
    segval = 0x4F;    
  else if (digit == 4)
    segval = 0x66;    
  else if (digit == 5)
    segval = 0x6D;    
  else if (digit == 6)
    segval = 0x7D;    
 
  return segval;
}
 

void roll_dice(unsigned char times)
{
  unsigned char i;
 
  for(i=0; i<times; i++)
  {
    DicePort = 0x06;    
    _delay_ms(200);
    DicePort = 0x5B;    
    _delay_ms(200);
    DicePort = 0x4F;    
    _delay_ms(200);
    DicePort = 0x66;    
    _delay_ms(200);
    DicePort = 0x6D;    
    _delay_ms(200);
    DicePort = 0x7D;    
    _delay_ms(200);
 
  }    
}
 

ISR(TIMER0_OVF_vect)
{
  seed++; // Increment the value in the variable seed
}