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working with right shift operators in C

ruchi kataria

I am facing a problem in using the right shift operator in C with keil.
The instruction is:for(i=0;i<=8;i++) { j=sum>>i; }
where sum= 32 bit no.
the instruction is not executed if the syntax is as shown above. but if i write a numerical value instead of using the variable name 'sum' then the instruction is easily executed. i need to use the variable name only. how do i fix this problem?

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  • 0 in reply to Andy Neil

    The 'for' loop is to right shift the contents of the variable 'sum'. 'sum' holds my 16 bit result. now i want to move this result in two 8 bits registers of the microcontroller. for that moving the lsb 8 bits of the result is simple. but the msb 8 bits have to be brought to the lsb position first to move it into an 8 bit reg. hence i used the for loop. but now as per your advice i have done away with the for loop and simply used:

    j=sum>>8;


    But still the instruction is not executed.
    is there any other alternate way of moving the 16 bit result in 'sum' to the registers of the microcontroller?

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  • 0 in reply to Andy Neil

    The 'for' loop is to right shift the contents of the variable 'sum'. 'sum' holds my 16 bit result. now i want to move this result in two 8 bits registers of the microcontroller. for that moving the lsb 8 bits of the result is simple. but the msb 8 bits have to be brought to the lsb position first to move it into an 8 bit reg. hence i used the for loop. but now as per your advice i have done away with the for loop and simply used:

    j=sum>>8;


    But still the instruction is not executed.
    is there any other alternate way of moving the 16 bit result in 'sum' to the registers of the microcontroller?

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