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accessing local "c" variables in inline assembly

MT Ol over 18 years ago

How do I access a local variable in assembly?

I have used the SRC to determine how the compiler created the variable. it changes it's name from variable to variable?nnn where nnn is a number.

How do I determine what nnn is? (other than looking at the .src file)
can I access the variable using the original label name?

If I use the variable:nnn , nnn will occasionally change and ten I get errors!

Help

Parents

0 He Xi over 18 years ago

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;

        //å¯¹RcvFIFOEmptyFlagLoï¼ŒRcvFIFOEmptyFlagHiæ¯ä¸€bitè¿›è¡Œæ£€æµ‹ï¼Œè‹¥ä¸º1ï¼Œåˆ™å¯¹åº"ä¸²å£æœ‰æ•°æ®
        //ç"±äºŽCè¯è¨€å¯¹ä½æ"ä½œæ•ˆçŽ‡ä½Žï¼Œä¸"æ¤å‡½æ•°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);  //è¯»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

}

Reply

0 He Xi over 18 years ago

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;

        //å¯¹RcvFIFOEmptyFlagLoï¼ŒRcvFIFOEmptyFlagHiæ¯ä¸€bitè¿›è¡Œæ£€æµ‹ï¼Œè‹¥ä¸º1ï¼Œåˆ™å¯¹åº"ä¸²å£æœ‰æ•°æ®
        //ç"±äºŽCè¯è¨€å¯¹ä½æ"ä½œæ•ˆçŽ‡ä½Žï¼Œä¸"æ¤å‡½æ•°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);  //è¯»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

}

Children

0 Dan Henry over 18 years ago in reply to He Xi

Forgive my ignorance here, but wouldn't it be ever so much easier to do all that with a little assembly language function?
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0 erik malund over 18 years ago in reply to Dan Henry

Forgive my ignorance here
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0 Andy Neil over 18 years ago in reply to erik malund

Ignorance of all the OP's carefully-considered reasons that made it not ever so much easier to do all that with a little assembly language function in his particular application...

Surely, he must have had plenty...

;-)
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0 HansBernhard Broeker over 18 years ago in reply to He Xi

a Sample:

This sample only proves that if you absolutely insist, you can drive a 10-inch nail into concrete using a fine-tip soldering iron, even if you have a perfectly usable hammer at hand.

It spectacularly fails to answer the actual question, though: why the heck would anyone want to do such a thing?
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0 erik malund over 18 years ago in reply to HansBernhard Broeker
this little snippet

#pragma endasm i=8; ACC=RcvFIFOEmptyFlagHi; #pragma asm

access the accumulator in C and, while it MAY not blow it all up, the practice is, at least, dangerous. Thus it does not matter if you can "access local "c" variables in inline assembly" since the whole mess, most likely, will blow up anyhow.

To the OP
rewrite the mess totally in assembler and look up the OVERLAYABLE command to the assembler, that will give you local variables in an assembler routine.

Erik
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