AT89s52-LCD12864 multi-page menu button selection operation

I haven't understood the code of this program yet, and I once again deeply discovered that my algorithm level is not good enough. What I learned today is okay, just some knowledge of those C files. Anyway, they are all optimization things, which will definitely be useful in the future. If you are interested in a few days, I will learn about AVR microcontrollers.

Program code: The hardware is the same as before, with the only difference being two more page-turning buttons. I haven't eaten yet, it's time to go eat. I really won't feel sleepy doing this.


[page]

#include 
#include 

sbit RS = P2^4;
sbit RW = P2^5;
sbit E = P2^6;
sbit PSB= P2^1; //Serial-parallel port selection end parallel high serial low
#define DataPort P0   

sbit KEY_ADD=P3^3; //key
sbit KEY_DEC=P3^4;

unsigned char curr,currold; //global variable, current arrow position

unsigned char code user16x16[]={ //arrow image
0x00,0x00,0x20,0x00,0x30,0x00,0x38,0x00,0x3C,0x00,0x3E,0x00,0x3F,0x00,0x3F,0x80,
0x3F,0xC0,0x3F,0x80,0x3F,0x00,0x3E,0x00,0x3C,0x00,0x38,0x00,0x30,0x00,0x20,0x00,
};

unsigned char code *MainMenu[]=
{
 {"1.Set 1"},
 {"2.Set 2"},
 {"3.Set 3"},
 {"4.Set 4"},
 {"5.Set 5"},
 {"6.Set 6"},
 {"7.Set 7"},
 {"8.Set 8"},
 {"9.Set 9"},
 {"0.Set0"},
};

/**********************************************
                  Delay function
*************************************************/
void DelayUs2x(unsigned char t)
{   
 while(--t);
}

void DelayMs(unsigned char t)
{
     
 while(t--)
 {
     DelayUs2x(245);
  DelayUs2x(245);
 }
}

/**********************************************
                Busy detection function
*************************************************/
void Check_Busy()
{  
    RS=0; //write command
    RW=1; //Read status
    E=1;
    DataPort=0xff;
    while((DataPort&0x80)==0x80);//Wait if busy
    E=0;
}

/**********************************************
                Write Command
*************************************************/
void Write_Cmd(unsigned char Cmd)
{
 Check_Busy();
 RS=0; //write command
 RW=0; //write
 E=1;
 DataPort=Cmd;
 DelayUs2x(5);
 E=0;
 DelayUs2x(5);
}

/**********************************************
                 Writing Data
*************************************************/
void Write_Data(unsigned char Data)
{
 Check_Busy();
 RS=1; //write data
 RW=0; //write
 E=1;
 DataPort=Data;
 DelayUs2x(5);
 E=0;
 DelayUs2x(5);
}

/**********************************************
               LCD screen initialization
*************************************************/
void Init_ST7920()
{  
   DelayMs(40); //Delay program greater than 40MS
   PSB=1; //Set to 8BIT parallel port working mode
   DelayMs(1); //delay
   Write_Cmd(0x30); //Select basic instruction set
   DelayUs2x(50); //delay greater than 100us
   Write_Cmd(0x30); //Select 8bit data stream
   DelayUs2x(20); //Delay greater than 37us
   Write_Cmd(0x0c); //Open the display (no cursor, no highlight)
   DelayUs2x(50); //delay greater than 100us
   Write_Cmd(0x01); //Clear the display and set the address pointer to 00H
   DelayMs(15); //Delay is greater than 10ms
   Write_Cmd(0x06); //Specify when reading and writing data,

Set the cursor moving direction and specify the displayed shift. The cursor moves from right to left by 1 position.
   DelayUs2x(50); //delay greater than 100us
}

/**********************************************
                User defined characters
*************************************************/
void CGRAM()
{
     int i;
     Write_Cmd(0x30);
     Write_Cmd(0x40);
     for(i=0;i<16;i++)
       {
        Write_Data(user16x16[i*2]);
        Write_Data(user16x16[i*2+1]);
      }
}   

/**********************************************
               Display user-defined characters
*************************************************/
void DisplayCGRAM(unsigned char x, unsigned char y)
{
 switch(y)
     {
   case 1: Write_Cmd(0x80+x);break;
   case 2: Write_Cmd(0x90+x);break;
   case 3: Write_Cmd(0x88+x);break;
   case 4: Write_Cmd(0x98+x);break;
      default:break;
  }
    Write_Data(00);
    Write_Data(00);
}         

/**********************************************
                  Display String
            x: horizontal axis value, range 0~8
            y: vertical coordinate value, range 1~4
*************************************************/
void LCD_PutString(unsigned char x, unsigned char y, unsigned char code *s)
{
 switch(y)
     {
   case 1: Write_Cmd(0x80+x);break;
   case 2: Write_Cmd(0x90+x);break;
   case 3: Write_Cmd(0x88+x);break;
   case 4: Write_Cmd(0x98+x);break;
      default:break;
  }
 while(*s>0)
   {
      Write_Data(*s);
      s++;
      DelayUs2x(50);
   }
}

/**********************************************
                     Clear screen
*************************************************/
void ClrScreen()
{
   Write_Cmd(0x01);
   DelayMs(15);
}    
/**********************************************
               Calling Display Update
*************************************************/
void DisplayUpdata(void)
{   
    unsigned char num;
  ClrScreen();
 num=sizeof(MainMenu)/sizeof(MainMenu[0]); //Determine the number of values ​​in the array
 if((0+(curr/4)*4)0)
     { curr--; }
    }
    }
 }  
  }
}