ps2keyboard demo code for 8052

#pragma code symbols debug objectextend

#include /* special function register declarations */
 /* for the intended 8051 derivative */

#include /* prototype declarations for I/O functions */


#define  BYTE   unsigned char
#define  WORD   unsigned int
#define  LONG   unsigned long
#define  dword  unsigned long
#define  DWORD  unsigned long
#define  byte   unsigned char
#define  word   unsigned int
#define  XBYTE  ((unsigned char volatile xdata *) 0)
#define  XWORD  ((unsigned int  volatile xdata *) 0)


#define NES     0x6000


    data union{
        LONG    l;
        BYTE    b[4];
    }lShift;
   
    data BYTE   bCnt;
/****************/
/* main program */
/****************/
void main (void)  { /* execution starts here after stack init */

#define  KEY_BREAK      0x1f800    
#define  BCNT_VALUE     0

    //BYTE code abBitHi[] ={0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80};
    //BYTE code KeyTable[][2]={}
   
    data BYTE   bKey=0xff, bC, bKeyTmp;
    //data WORD   wKb;
    //data long   lBrk;
    data union{
        LONG    l;
        BYTE    b[4];
    }lTmp;
    bit         fParity, fP;
   
    TCON=0x01;  //bit0: 1/0 falling edge/low level triggered external interrupts
    IP=0x01;    //bit0:Externl interrupt 0 Priority control bit
    IE=0x81;    //bit0:Enable External interrupt 0 control bit
                //bit7:All control bit

    XBYTE[NES]=0x00;  

  ///if (bCnt>=BCNT_VALUE) {
  while(1){
    T0=~T0;
 
    bCnt=BCNT_VALUE;
    lTmp.l=lShift.l;

    if ((((lTmp.b[1] & 0x1f)==0x1f) && ((lTmp.b[2] & 0xfc)==0x80)) ||
        ((lTmp.b[0]==0xfc) && (lTmp.b[1]<=0x10)))
        {
            //fBrk=1;
            bKey &= 0x7f;
    }      
    else if (((lTmp.b[0] & 0xa0)==0x80) &&       //stop bit=1, data bit7=0
             ((lTmp.b[1] & 0x20)==0x00) ){       //start bit==0 bit0 , data bit7==0
            if (lTmp.b[0] & 0x40)   fP=1;   //parity bit    bit9  
            else                    fP=0;
            lTmp.l<<=2;
            bKeyTmp=lTmp.b[0];
            fParity=1;
            for (bC=0; bC<=7; bC++){
                if ((lTmp.b[0] & 0x80)!=0) fParity=~fParity;
                lTmp.b[0]<<=1;
            }
            if (fP==fParity) {
                //fOk=1;
                //bKey=KeyTable[bKeyTmp];
                bKey=bKeyTmp | 0x80;
            }  
        }




    P1=bKey;  
    XBYTE[NES]=bKey;
   
  }
  ////else bCnt++; //while (1)
} //void main (void)



/**/void vInt0() interrupt 0 using 2
{
    bit fT0;
    fT0=INT1;

    lShift.l>>=1;  
    if (fT0==0x01) lShift.b[0] |= 0x80;
    ///bCnt=0;

 
}

/* link
hello.obj

XDATA(0) IDATA(80H) RAMSIZE(256) SYMBOLS

*/