软件查询方式实现数码管闪烁

#include <reg52.h>
#define uint unsigned int 
#define uchar unsigned char 
sbit led1 = P1^7 ;
sbit led2 = P2^3 ;
uint i,num ;

void init(){
    TMOD = 0X01;
    TR0 = 1;
}
void main()
{
    while(1)
        {
        init();
        for(i=0;i<2;i++)
            {
          while(num>50000)
                    {
              num = TH0*256+TL0;
            }
                    TH0 = 0;
                    TL0 = 0;
      }
            led1 = ~led1;
            led2 = ~led2;
      }
}