#define F_CPU 4000000UL // 4 MHz

#include <util/delay.h>
#include <avr/io.h>

volatile unsigned char k,pa,pc;
volatile unsigned char* port_pointer;
int main (void){
	unsigned char i,j;	
	DDRA=0xff;
	DDRC=0xff;
	PORTA=1;
	PORTC=~(1<<0);	
	while(1){		
		for (i=0;i<7;i++){
			if (j&1){
				port_pointer=&PORTA;
			}else{
				port_pointer=&PORTC;
			}		
			if ((j&2)==0){	//编译器未优化,此为循环移位
				*port_pointer=(*port_pointer>>(8-1))|(*port_pointer<<1);
			}else{
				*port_pointer=(*port_pointer>>1)|(*port_pointer<<(8-1));
			}			
			pa=PORTA;	//使用push pop更佳
			pc=PORTC;
			for (k=0;k<4;k++){		
				PORTA=0;
				if (k&1){
					PORTA=pa;
					PORTC=pc;
				}else{
					PORTA=0b00011000;
					PORTC=~0b00011000;			
				}	
				DDRA=0xff;
				_delay_ms(50);	//proteus不响应快扫,故改慢,增大k的终值减少延时结果相同而且不闪
				DDRA=0x00;
			}
		}
		j++;
	
	}
}