#define PORTA_DDR*(volatile uint8_t *)0X21
#define PORTA_DATA*(volatile uint8_t *)0X22

#define PORTB_DDR*(volatile uint8_t *)0X24
#define PORTB_DATA*(volatile uint8_t *)0X25

int main(){
  PORTA_DDR=0XFF;
  PORTB_DDR=0XFF;
  volatile long i,j;
  while(1){
    PORTA_DATA=0X00;
    for(i=0;i<=7;i+=2){
      PORTA_DATA|=(1<<i);
      PORTA_DATA|=(1<<i+1);
      for(j=0;j<400000;j++){}
      PORTA_DATA=0X00;
    }
    PORTB_DATA=0X00;
    for(i=0;i<=7;i+=2){
      PORTB_DATA|=(1<<i);
      PORTB_DATA|=(1<<i+1);
      for(j=0;j<400000;j++){}
      PORTB_DATA=0X00;
    }
     PORTB_DATA=0X00;
    for(i=7;i>=0;i-=2){
      PORTB_DATA|=(1<<i);
      PORTB_DATA|=(1<<i-1);
      for(j=0;j<400000;j++){}
      PORTB_DATA=0X00;
    }
     PORTA_DATA=0X00;
    for(i=7;i>=0;i-=2){
      PORTA_DATA|=(1<<i);
      PORTA_DATA|=(1<<i-1);
      for(j=0;j<400000;j++){}
      PORTA_DATA=0X00;
    }
  }
}