Communication example between MCU and PC

#define SENDBUFSIZE 0x0f
#define BR_19K2 0xfd
#define RMAX 0x10 //Must be an integer power of 2. Seen on 21ic, seems to be the idea of ​​"Senior Liu"
unsigned char xdata *cpSendBufPtr;
unsigned char cFront;
unsigned char cBack;
unsigned char sendData;
bit cTranFlag;
unsigned char cTranData;
bit cRecFlag;
unsigned char cRecData;
bit cJudge;
unsigned char temp;

void HardWareInit();
void Uart_Init(void);
void Uart_Init(void); 
void COMM_Init(unsigned char cBaudRate, bit bSMOD);   //初始化UART

//sfr AUXR = 0x8E;
//MODE COM4 19200,0,8,1;ASSIGN COM4 SOUT
//The baud rate is 19200Hz. Will the data received by the serial port be forwarded again?
//The data receiving speed may be greater than the sending speed. Increase the buffer and save the received data first.
main()
{
 sendData=0;
 cFront=0; //
 cBack=0;//
 cRecFlag=0; //No data received yet
 cTranFlag=1;//After the system is reset, as long as the queue is not empty, data can be sent at any time
 RS0 = RS1 = 0;// Use register group 0  
    AUXR = 0x01; //Disable ALE signal output
 EA = 0;
 P1 = 0xFF;
    P2 = 0xFF;
    P3 = 0xFF;
    P4 = 0xFF;
 
 ES = 0;
 TR1 = 0;
 TMOD = TMOD & 0x0f | 0x20;
 TH1 = BR_19K2;
 TL1 = BR_19K2; ////------------------------------------------------------------------------------------------
 PCON = 0x80; // If SMOD=1, baud rate multiplication
 
 SCON = 0x50; // 8-bit
 IP = 0x10; // Serial port priority interrupt
 ES = 1;

 // wifi module: baud rate 19200/38400/57600/115200bps data bit: 8bits check bit: none stop bit: 1bit flow control: none
 EA = 1;
 TR1 = 1;
// SBUF=0x12;
 while(1)
 {
/*   
*/// 14 15 16 17 18 19 20 21
   if(cRecFlag)
   {
    temp=((cFront+1)^cBack)&0x0f;
  
    if(temp!=0) //The circular linked list is not full yet, you can continue to add data
    {
    cFront=cFront+1;
    cFront=cFront&(RMAX-1);
  cpSendBufPtr[cFront]=cRecData;
  cRecFlag=0;
  }
   }
   if(cTranFlag) 
   {
  temp=(cBack^cFront)&0x0f;//A new number is sent, this place is cBack instead of cBack+1
  
    if(temp!=0) //Data can be sent when the circular linked list is not empty
    {

    cBack=cBack+1;
    SBUF=cpSendBufPtr[cBack];
    cpSendBufPtr[cBack]=0x00;
    cBack=cBack&(RMAX-1);
    cTranFlag=0;
    }
   }   
 }
}

/*******************************************************************************
// Function: UART completes data transmission and reception and generates an interrupt program
// Input parameter: None
// Output parameter: None
// Return value: None
******************************************************************************/
void COMM_INT() interrupt 4 using 3
{ 
  if(RI)//If the received data is being processed, the data in SBUF is discarded ^cRecFlag
 {
  cRecData=SBUF;
  cRecFlag=1;
  RI=0;
 }
 if(TI) 
 {
  cTranFlag=1;
  TI=0;
 }//Sending is completed, and cTranData is assigned a new value*/
}