keil C ´ÓÁãѧÆð ½Ìѵ1

#include<reg52.h>
#define uchar unsigned char
#define uint unsigned int
uchar num;
void main()
{
 TMOD=0x01;
 TH0=(65536-45872)/256;
 TL0=(65536-45872)%256;
 EA=1;
 ET0=1;
 TR0=1;
 P1=0xFF;
 while(1);
}
void T0_time() interrupt 1
{
               TH0=(65536-45872)/256;
               TL0=(65536-45872)%256;
               num++;
               if(num==20)
 {
               num=0;
               if(P1==0x00)
  {
              P1=0xFF;
  
  }
               else
               P1=P1>>1;
 }
}
Èç¹ûÔÚinterrupt·þÎñº¯ÊýÖУ¬ifÅжÏP1==0x00д³ÉP1=0x00£¬ÄǾͳöÏÖ±àÒ뾯ºÅ£¨²¢·Ç´íÎó£©
warning C276: constant in condition expression ¾¯¸æ¡£
½ñÌì¸É¸É¿ªÊ¼Ñ§Ï°£¬¾ÍÓöµ½ÁËÓÉÓÚ´ÖÐÄÒýÆðµÄÎÊÌâ¡£
¿´À´Ò»¸öºÃµÄ±à³ÌÏ°¹ßÊDZà³ÌÕßʵ¼ùµÄ±ØÒªËØÖÊ¡£