Dennis Crawley wrote:
> I wonder if is possible to rotate a 1 in a nibble with out an auxiliary
> register and without change the other nibble. This is my approach with a
> temporary register, rotating the high.
>
>        movfw   Reg         ;Reg= 0001.efgh
>        andlw   0xf0        ;
>        movwf   Tmp         ;
>        rlf     Tmp,F       ;
>        btfsc   STATUS,C    ;
>        bsf     Tmp,4       ;
>        movlw   0x0f        ;Clean before write
>        andwf   Reg,F       ;
>        movfw   Tmp         ;
>        iorwf   Reg ,F      ;Reg= 0010.efgh

     movf   reg, w    ;get entire register to rotate high nibble of
     andlw  b'11110000' ;mask in high nibble only
     addwf  reg       ;double high nibble to shift it 1 bit left
     skip_ncarr       ;the 1 bit didn't shift out the MSB ?
     bsf    reg, 4    ;it did, start a new 1 bit in LSB

That's 5 instructions.  Scott can probably do it in 5 or 6 less.


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