Below is some working code. Note that the branch instruction is two
bytes long, but the goto is four, thus some of the problem. Also, you
need to use the rlncf so you don't accidentally end up on an odd address
(though that might be thrown out when it gets loaded into the pc).

Harold

        movlw   high(RXJA)
        movwf   pclath          ; Update pc latch for table calls
        rlncf   RxState,0       ; Get receive state*2 in W since bra instructions are 2
bytes long
        andlw   0x07            ; Get rid of invalid states
        addlw   low(RXJA)       ; w now holds low half of address we want to jump to
        skpnc
        incf    pclath,1        ; Add carry into pclath if needed
        movwf   pcl             ; Jump into table
RXJA
        bra     RxState0        ; Go handle wait for FE (state 0)
        bra     RxState1        ; Go handle wait for start code (state 1)
        bra     RxState2        ; Go handle receive data (state 2)
        return                  ; should never be executed (invalid state 3)



On Tue, 13 Aug 2002 11:21:49 -0300 "Edson Brusque (Listas)"
<brusque.listas@CITRONICS.COM.BR> writes:
> Hello,
>
>     I'm porting a software that is running ok on a PIC16F877 to a
> PIC18F452
> and now I'm having problems with the computed goto's.
>
>     On the PIC16:
>
>     MOVLW  0x01
>     MOVWF  PCLATH
>     MOVF   state,W_
>     ADDWF  PCL,F_
>     GOTO   case0
>     GOTO   case1
>     GOTO   case2
>     etc
>
>     On the PIC18 strange things happen:
>     MOVLW  0x01
>     MOVWF  PCLATH
>     RLCF   dkstate, W_
>     ADDWF  PCL
>     GOTO   case0
>     GOTO   case1
>     GOTO   case2
>     etc
>
>     Someone have an example code about computed goto's on a PIC18?
>
>     I've seen the "Unlimited computed goto (or table lookup)" page
> by Bob
> Ammerman on PICLIST, but it seens overkill. I need very fast code.
>
>     Thank you very much,
>
>     Brusque
>
> -----------------------------------------------------------------
> Edson Brusque                 C.I.Tronics Lighting Designers Ltda
> Research and Development               Blumenau  -  SC  -  Brazil
> Say NO to HTML mail                          www.citronics.com.br
> -----------------------------------------------------------------
>
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>
>

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