Thanks Bob Ammerman.
You help me a lot. See how I coded the program:

     clrf acionador    ;string to AND with portB
     movf canal, w
     movwf valor            ;a channel copy
     movwf contador     ; set the counter
     bsf status, c
     rlf acionador, f        ; rotates the control word
     decfsz contador
     goto $ - 2
     movf sendreg, w
     andwf acionador, w    ;verify if the channel is on low or high level
     btfsc status, z
     goto _seta                    ; go to the set routine
     comf acionador, w
     andwf sendreg, w        ;clear bit
     call ser_out                ;put the value on portb
     return
_seta
     movf acionador, w        ;set bit
     iorwf sendreg, w
     call ser_out                    ;put the value on portb
     return

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