Bob wrote:

>I don't think this will work. If movff won't work directly to PCL, I doubt
>it will work indirectly.

Yes, I'm afraid of that, too

>
>You might try something like this:
>
>     push
>     movwf    PCLATH
>     movf      TBLPTRL,W
>     movwf    TOSL
>     movf       TBLPTRH,W
>     movwf    TOSH
>     movf       PCLATH,W
>     return


Yep, I've tried that, but the bad thing about it is that one must
control interrupts around it. e.g.


        bcf     0FF2h,7         ; disable INTs
        push                    ; required, as we'll undo it with a return
        clrf    TOSU            ; TOS = jump-to address
        movff   TBLPTRH,TOSH    ;  ""
        movff   TBLPTRL,TOSL    ;  ""
        bsf     0FF2h,7         ; re-enable INTs
        return

And that still won't work if it's called from within an ISR
(unintended re-enabling of interrupts). It does work OK otherwise, at
least in the SIM.

Is it the case that the only instruction that can reliably change PCL
on the 18 is addwf?
--

  ______________________________________
   Andrew E. Kalman, Ph.D.   aek@pumpkininc.com

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