#include<reg52.h>
#include<intrins.h>
#include<math.h>
#include<stdio.h>
#define uchar unsigned char
#define uint unsigned int
void delay(uint z)
{
uint x,y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}
void main()
{
uchar aa;
P0=0xfc;
while(1)
{
delay(500);
aa=P0;
aa=_crol_(aa,1);
P0=aa;
}
}