It does have to work on a 16c55 (actually an SX 28) but can't I just:

        MOVLW 0xEF
        ADDF    BufTyp, W
        SKPNC
        SKPDC
        RETLW 0

???

Seems like that would work and its darn tricky... Nice idea! Thanks.

---
James Newton (PICList Admin #3)
mailto:jamesnewton@piclist.com 1-619-652-0593
PIC/PICList FAQ: http://www.piclist.com or .org

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Andrew Warren
Sent: Tuesday, January 23, 2001 14:22
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC:] code challenge - test both nibbles non-zero


j newton <jamesnewton@geocities.com> wrote:

> Ok, I'm storing two 4 bit wide variables in one byte (file register)
> and I need to test that neither variable is zero. i.e. the byte is not
> 0X or X0 hex were X is any 4 bit value. The best I can do is 7, any
> better?
>
>         P = pic16c55
> ....
>         MOVF BufTyp,w
>         ANDLW 0x0F
>         BTFSC status,z
>          RET
>         SUBWF Buftyp,w
>         BTFSC status,z
>          RET

James:

Does it HAVE to work on a 16C55?  If you had an ADDLW instruction,
you could do this:

    MOVF    BufTyp,W
    ADDLW   0xEF
    SKPNC
    SKPDC
    RETLW   0

-Andy


=== Andrew Warren --- aiw@cypress.com
=== Staff Systems Engineer, IPD
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation.

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