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Problem with function call

Mohammad Adel

In the following code:
********************************************
#include <REG51.H>

unsigned char rem(unsigned char d1,unsigned char d2)
{

B=d2;
ACC=d1;
#pragma asm
DIV AB;
#pragma endasm
return B;
}

void main(void)
{
while(1)
{
unsigned char x,y,z;
P0=255;
x=65;
y=10;

z=rem(x,y);
P0=z;
}
}

*****************************************
I noticed that the instruction d1=ACC is not converted into assembly (Keil ignores this line).

Is this any reason behind that?..How can I solve the problem?

Thanks

Parents
  • 0

    hi,
    why do you try to play with ASM for such purposes? Next C lines produce the same result:

    unsigned char div(unsigned char x, unsigned char y)
{
	return (x/y);
}

unsigned char rem(unsigned char x, unsigned char y)
{
	return  (x%y);
}

    Output file produced with compiler is:
    unsigned char div(unsigned char x, unsigned char y)
MOV      A,R7
MOV      B(0xF0),R5
DIV      AB
MOV      R7,A
RET

unsigned char rem(unsigned char x, unsigned char y)
MOV      A,R7
MOV      B(0xF0),R5
DIV      AB
MOV      R7,B(0xF0)
RET

    So what is the reason to do same things which compiler may do itself?

    Regards,
    Oleg

Reply
  • 0

    hi,
    why do you try to play with ASM for such purposes? Next C lines produce the same result:

    unsigned char div(unsigned char x, unsigned char y)
{
	return (x/y);
}

unsigned char rem(unsigned char x, unsigned char y)
{
	return  (x%y);
}

    Output file produced with compiler is:
    unsigned char div(unsigned char x, unsigned char y)
MOV      A,R7
MOV      B(0xF0),R5
DIV      AB
MOV      R7,A
RET

unsigned char rem(unsigned char x, unsigned char y)
MOV      A,R7
MOV      B(0xF0),R5
DIV      AB
MOV      R7,B(0xF0)
RET

    So what is the reason to do same things which compiler may do itself?

    Regards,
    Oleg

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