accessing local "c" variables in inline assembly

How do I access a local variable in assembly?

Only slightly simplified answer: you don't. Inline assembly in C51 isn't integrated anywhere near well enough with the C compiler to allow such tricks.

Generally, the best idea is to re-evaluate the whole plan: are you absolutely sure that you need inline assembly for the task at hand?

Try writing a dummy C subroutine passing the variable to it as an argument & returning it unchanged. Check the compiled assembly code & add any instructions to the code between the subroutines entry point & it's return of the value.

Don

here is a Sample:

void ProcessSerialSwitch()
{
        data unsigned char i;
        data unsigned char RcvFIFOEmptyFlagLo;
        data unsigned char RcvFIFOEmptyFlagHi;
//      char code Mask[8]={0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80};

/*      MemSwitchReg();
        RcvFIFOEmptyFlagLo=XBYTE[RegAddrReceiveFIFOEmpty];
        RcvFIFOEmptyFlagHi=XBYTE[RegAddrReceiveFIFOEmpty+1];
        MemSwitchRam();
*/
RcvFIFOEmptyFlagLo=0xFF;
RcvFIFOEmptyFlagHi=0xFF;

        //对RcvFIFOEmptyFlagLo，RcvFIFOEmptyFlagHiæ¯ä¸€bit进行检测，若为1，则对åº"串å£æœ‰æ•°æ®
        //ç"±äºŽC语言对ä½æ"作效率低，ä¸"此函数ç»å¸¸è¢«è°ƒç"¨ï¼Œæ"¹ä¸ºæ±‡ç¼–
        //for (i=0;i<SerialCount;i++) {
        //      if (i<8) {if (RcvFIFOEmptyFlagLo&Mask[i]) SerialSwitchReadChar(i);}
        //              else if (RcvFIFOEmptyFlagHi&Mask[i-8]) SerialSwitchReadChar(i);
        //}


        ACC=RcvFIFOEmptyFlagLo;

#pragma asm

        checklo:
                //MOV      A,RcvFIFOEmptyFlagLo
                JZ      checkhi

//              CLR      A
#pragma endasm
                i=0;
#pragma asm

//              MOV      i,A

        testlo:
#pragma endasm
        ACC=RcvFIFOEmptyFlagLo;
#pragma asm
//              MOV      A,RcvFIFOEmptyFlagLo
                JZ       checkhi
        lblrorlo:
                CLR      C
                RRC      A
                JC               doreceivelo
                JZ       checkhi
//              INC              i
#pragma endasm
                i++;
#pragma asm
                JMP              lblrorlo

        doreceivelo:
        //      MOV              RcvFIFOEmptyFlagLo, A
#pragma endasm
        RcvFIFOEmptyFlagLo=ACC;
        SerialSwitchReadChar(i);  //读å–æ•°æ®
        i++;
        ACC=RcvFIFOEmptyFlagLo;
#pragma asm
                //inc      i
                //MOV      A, RcvFIFOEmptyFlagLo
                JNZ      lblrorlo

        checkhi:

#pragma endasm
                i=8;
                ACC=RcvFIFOEmptyFlagHi;
#pragma asm
//              MOV      i,8
//      testhi:
                //MOV      A, RcvFIFOEmptyFlagHi
                JZ       returnintr

        lblrorhi:
                CLR      C
                RRC      A
                JC       doreceivehi
                JZ       returnintr
#pragma endasm
                i++;
#pragma asm
                //INC      i
                JMP      lblrorhi
        doreceivehi:
//              MOV              RcvFIFOEmptyFlagHi, A
#pragma endasm
        RcvFIFOEmptyFlagHi=ACC;
        SerialSwitchReadChar(i);
        i++;
        ACC=RcvFIFOEmptyFlagHi;
#pragma asm
                //inc      i
        //      MOV      A,RcvFIFOEmptyFlagHi
                JNZ      lblrorhi

        returnintr:
                RET


#pragma endasm

}