【单片机期中测试】3.按键控制流水灯循环

#include<reg52.h>
#define uc unsigned char
sbit KEY1 = P3^1;
void delay(uc c)
{
  uc a,b;
  for(;c>0;c--)
    for(a=38;a>0;a--)
      for(b=130;b>0;b--);
}
void main()
{
  uc i=1,dir=0;
  P2 = ~i;
  while(1)
  {
    if(KEY1 == 0)
    { 
      delay(1);
      while(KEY1 == 0);
      delay(1);
      while(1)
      {
        if(dir==0)
        {
          i<<=1;
          if(i==0) 
          {
            i=0x80;
            dir=1;
          }
        }
        if(dir==1)
        {
          i>>=1;
          if(i==0)
          {
            i=1;
            dir=0;
          }
        }     
        P2=~i;
        delay(20);
      } 
    }
  }
}