#include <reg51.h>

void delay(unsigned int t);

unsigned char buffer;
sbit PB1 = P3^2;     //設定PB1代表P3.2
sbit PB2 = P3^3;     //設定PB1代表P3.3

void main(void)
{
  buffer = 0;     //設定buffer初值為0
  while(1)
   {
      while(PB1 == 0)       //檢查PB1是否為0
       {
         delay(3);          //延遲, 判斷是否為彈跳訊號
         if (PB1 == 0)        //如果PB1仍然為0, 則
           {
            buffer++;         //buffer內的值加1
            P2 = ~buffer;   //將buffer內的值反向送到P2顯示
           }
         while(PB1 == 0);     //如果PB1仍然為0, 則停在此行，直到放開
       }

      while(PB2 == 0)       //檢查PB2是否為0 
       {
         delay(3);
         if (PB2 == 0)
           {
            buffer--;         //buffer內的值減1
            P2 = ~buffer;   //將buffer內的值反向送到P2顯示
           }
         while(PB2 == 0);
       }
   }
}


void delay(unsigned int t)
{
   unsigned int i;
   while(t--)
     {
      i=10000;
      while(i--);
     }
}