DIY 1602 clock with adjustable display

#include
#define uint unsigned int
#define uchar unsigned char

sbit key0 = P3^0; //Time adjustment minute and second switching
sbit key1 = P3^1; //time addition
sbit key2 = P3^2; //time subtraction
sbit lcdrw = P2^5; //Read and write operation selection, 1 for reading and 0 for writing
sbit rs = P2^6; //register selection, 1 data 0 instruction
sbit lcden = P2^7; //enable signal
uchar code table[] = {" 2010-10-22 FRI"};
uchar code table1[] = {"    00:00:00"};
uchar count,shi,fen,miao,s1num;

void delay(uint z)
{
 uint x,y;
 for(x = z;x > 0;x --)
  for(y = 110;y > 0;y --);
}

void write_com(uchar com) //write instruction
{
 rs = 0;
 lcden = 0;
 P0 = with;
 delay(5);
 lcden = 1;
 delay(5);
 lcden = 0; 
}

void write_date(uchar date) //write data
{
 rs = 1;
 lcden = 0;
 P0 = date;
 delay(5);
 lcden = 1;
 delay(5);
 lcden = 0;
}

void init()
{
 flying number;
 lcdrw = 0;
 lcden = 0;
 write_com(0x38);
 write_com(0x0c);
 write_com(0x06);
 write_com(0x01);//clear

 write_com(0x80); //LCD first line address
 for(num = 0;num < 15;num ++)
 {
  write_date(table[num]);
  delay(5); 
 }
 write_com(0x80+0x40); //LCD second line address
 for(num = 0;num < 12;num ++)
 {
  write_date(table1[num]);
  delay(5);
 }

 TMOD = 0x01;
 TH0 = (65536-50000)/256;
 TL0 = (65536-50000)%256;
 EA = 1; // Enable interrupt
 ET0 = 1; //Timer 0 interrupt
 TR0 = 1; //Start the timer
}

void write_sfm(uchar add,uchar date)
{
 flying shi,ge;
 shi = date/10;
 ge = date%10;
 write_com(0x80+0x40+add);
 write_date(0x30+shi);
 write_date(0x30+ge);
}

void keyscan()
{
 if(key0 == 0)
 {
  delay(5);
  if(key0 == 0)
  {
   s1num ++;
   while(!key0);
   if(s1num == 1)
   {
    TR0 = 0;
    write_com(0x80+0x40+10);
    write_com(0x0f);
   }

   if(s1num == 2)
   {
    write_com(0x80+0x40+7);
   }

   if(s1num == 3)
   {
    write_com(0x80+0x40+4);
   }

   if(s1num == 4)
   {
    s1num = 0;
    write_com(0x0c); //No flash mark
    TR0 = 1;
   }
  }
 }

 if(s1num != 0)
  {
   if(key1 == 0)
   {
    delay(5);
    if(key1 == 0)
    {
     while(!key1);
     if(s1num == 1)
     {
      miao ++;
      if(miao == 60)
      miao = 0;
      write_sfm(10,miao);
      write_com(0x80+0x40+10);
 
     }

     if(s1num == 2)
     {
      fen ++;
      if(fen == 60)
      fen = 0;
      write_sfm(7,fen);
      write_com(0x80+0x40+7); 
     }

     if(s1num == 3)
     {
      it ++;
      if(shi == 24)
      it = 0;
      write_sfm(4,shi);
      write_com(0x80+0x40+4); 
     }
    }
   }

   if(key2 == 0)
   {
    delay(5);
    if(key2 == 0)
    {
     while(!key2);
     if(s1num == 1)
     {
       if(miao == 0)
       {
        miao = 60;
        write_sfm(10,miao);
        write_com(0x80+0x40+10);
       }
       miao --;
       write_sfm(10,miao);
       write_com(0x80+0x40+10);
      
     }

     if(s1num == 2)
     {
      if(fen == 0)
       {
        fen = 60;
        write_sfm(7,fen);
        write_com(0x80+0x40+7);
       }
       fen --;
       write_sfm(7,fen);
       write_com(0x80+0x40+7); 
     }

     if(s1num == 3)
     {
        if(shi == 0)
       {
        it = 24;
        write_sfm(4,shi);
        write_com(0x80+0x40+4);
       }
       he --;
       write_sfm(4,shi);
       write_com(0x80+0x40+4);
     }
    }
   }

  } 
}

void main()
{
 heat();
 while(1)
 {
  keyscan();
  
 // while(1);
 }
}

void timer0() interrupt 1
{
 TH0 = (65536-50000)/256;
 TL0 = (65536-50000)%256;
 count ++;
 if(count == 20)
  {
   count = 0;
   miao ++;
   if(miao == 60)
   {
    miao = 0;
    fen ++;
    if(fen == 60)
    {
     fen = 0;
     it ++;
     if(shi ==24)
     {
      it = 0;
     }
     write_sfm(4,shi);
    }
    write_sfm(7,fen);
   }
   write_sfm(10,miao);
  } 
}