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Use MACRO C "#define value" in MACRO ASM

I use KeilC uVision4 for 89C51 MCU.
I use "Inline ASM Code", like this :

    void main() {
        #pragma ASM
            MOV R7, #(80000/40000)
        #pragma ENDASM
    }

-> When COMPILE, ASM result file give a wrong value to R7

        MOV R7, #0x00

But when i change like this :

    void main() {
        #pragma ASM
            MOV R7, #(60000/30000)
        #pragma ENDASM
    }

-> The COMPILER give correct value to R7

        MOV R7, #0x02

=> Seem, there must be a restriction when the ASM Compiler calculate (80000/40000) ?
=> And is there any way to pass this restriction. Please help me !
Regards !

Parents

0 Vu Lam Dien over 15 years ago in reply to Andy Neil

Thanks a lot for your helps. In a couple of days, I found that the Macro should be as following :

// Delay Routine
void RoutineDelayMCs(unsigned int interval) {
    #pragma ASM
        DJNZ R7, $
        DJNZ R6, $-2
    #pragma ENDASM
}

// Delay Macro -> Calculate interval to pass into Delay Routine
#define MacroDelayMCs(interval) \ 
    ((!(((interval)/2) - 257*((((interval)/2)+256-1)/257))) ? \ 
    RoutineDelayMCs(257*((((interval)/2)+256-1)/257)) : RoutineDelayMCs(((interval)/2)+256-(((interval)/2)+256-1)/257))

// Offset Macro -> Calculate offset MCs of MOV, LCALL, RET ... command -> for better accuracy
// Accuracy (if interval even, error = 0; if interval odd, error = -1 MCs
// interval apply Range : 14 -> 131592
#define DelayMCs(interval) \ 
    MacroDelayMCs(interval-10)


void main() {
    DelayMCs(14);     // This call delay 14 Machine Cycles
    DelayMCs(512);    // This call delay 512 MCs
    DelayMCs(131592); // This call delay 131592 MCs
}

And ... It works fine !
Of course, manually hacking the registers is really Bad. I will put the RoutineDelayMCs in an ASM Module later.

Thanks again ... all friends, Regards !

Reply

0 Vu Lam Dien over 15 years ago in reply to Andy Neil

Thanks a lot for your helps. In a couple of days, I found that the Macro should be as following :

// Delay Routine
void RoutineDelayMCs(unsigned int interval) {
    #pragma ASM
        DJNZ R7, $
        DJNZ R6, $-2
    #pragma ENDASM
}

// Delay Macro -> Calculate interval to pass into Delay Routine
#define MacroDelayMCs(interval) \ 
    ((!(((interval)/2) - 257*((((interval)/2)+256-1)/257))) ? \ 
    RoutineDelayMCs(257*((((interval)/2)+256-1)/257)) : RoutineDelayMCs(((interval)/2)+256-(((interval)/2)+256-1)/257))

// Offset Macro -> Calculate offset MCs of MOV, LCALL, RET ... command -> for better accuracy
// Accuracy (if interval even, error = 0; if interval odd, error = -1 MCs
// interval apply Range : 14 -> 131592
#define DelayMCs(interval) \ 
    MacroDelayMCs(interval-10)


void main() {
    DelayMCs(14);     // This call delay 14 Machine Cycles
    DelayMCs(512);    // This call delay 512 MCs
    DelayMCs(131592); // This call delay 131592 MCs
}

And ... It works fine !
Of course, manually hacking the registers is really Bad. I will put the RoutineDelayMCs in an ASM Module later.

Thanks again ... all friends, Regards !

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