MCU learning - independent button P1^0

Title: The first three digits of the digital tube display a stopwatch, which runs from 000 to 999 at a speed of 0.01 seconds. When an independent button is pressed, the stopwatch stops, and it continues to run after the hand is released. (Using the timer interrupt method) 

Solution: (C language programming)

#include
#include
#define uint unsigned int
#define uchar unsigned char
uchar bai,shi,ge,num;
uint shu;
sbit s=P1^0;
sbit le=P3^6;
void delay(uint a);
void dis();
void display(uchar ba,uchar sh,uchar g);
uchar code tabledu[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,
0xf8,0x80, 0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e,0x89,0x86,0xc7,0xc7,0xc0,0xff};
uchar code tablewe[]={0xff,0xfe,0xfd,0xfb,0xf7,0xef,0xdf,0xbf,0x7f};
void init()
{
 shu=0;
 TMOD=0x11;
 TH0=0xd8;
 TL0=0xf0;
 EA=1;
 ET0 =1;
 TR0=1;
}
void main()
{
 init();
 while(1){   
  if(s==0){
   delay(5);
   if(s==0){
      TR0=0;
    dis() ;
    }
   }
  else
    {
     TR0=1;
     dis();
    }
 }
}
void time0() interrupt 1
{
 TH0=0xd8;
 TL0=0xf0;
 num++;
 shu++;
 if(shu==999)
    shu=0;
 bai=shu/ 100;
 shi=shu%100/10;
 ge=shu%10; 
}
void display(uchar ba,uchar sh,uchar g)
{
 le=1;
 P2=tablewe[1];
 le=0;
 le=1;
 P0=tabledu[ba];
 le=0;
 delay(5);
 le=1 ;
 P2=tablewe[2];
 le=0;
 le=1;
 P0=tabledu[sh];
 le=0;
 delay(5);
 le=1;
 P2=tablewe[3];
 le=0;
 le=1 ;
 P0=tabledu[g];
 le=0;
 delay(5); 
}
void dis()
{
 if(num%1==0)
     {
      display(bai,shi,ge);
     }
    if(num%10== 0)
     {
      display(bai,shi,ge);
     }
    if(num==10)
     {
      num=0;
      display(bai,shi,ge);
     }
}

void delay(uint a) {
 uint i,j;
 for(j=a;j>0;j--)
    for(i=250;i>0;i--);
}