Shane Nelson <PICLIST@MITVMA.MIT.EDU> wrote:

> The goal is to have a routine that increments and keeps track of
> time in a BCD format.
>
> Points are scored as follows:
>         1 point for each ROM location used.
>         3 for each RAM.
>
> My code scores 43 points. Best score is the lowest.
> Haven't tested it yet so I dont know if it works or not.

Shane:

Your code doesn't work; neither does Tony Nixon's.

This code DOES work; it increments the time, stored in packed-BCD
format (two decimal digits per byte) in registers HOURS, MINUTES, and
SECONDS.

It uses those three registers plus the FSR, and 24 words of ROM
(including the RETURN).  It'll run on any of the PICs, including the
12-bit parts.

SECONDS, MINUTES, and HOURS must be stored in consecutive registers,
in that order... But they can be on any register-page.

By my count, this routine scores 4 * 3 + 24 = 36 points.  I expect,
of course, that John, Scott or Dmitri will be able to do better.

TICK:   MOVLW   SECONDS
        MOVWF   FSR
        CALL    SUB1
        CALL    SUB0
        CALL    SUB0
        ADDWF   INDF,W
        SKPNC
        CLRF    INDF
        RETURN

SUB0:   INCF    FSR
        SKPNC
SUB1:   INCF    INDF

        MOVLW   6
        ADDWF   INDF,W
        XORWF   INDF,W
        ANDLW   11110000B
        MOVLW   6
        SKPNZ
        ADDWF   INDF

        MOVLW   0100H - 060H
        ADDWF   INDF,W
        SKPNC
        CLRF    INDF

        RETLW   0100H - 024H

-Andy

=== Andrew Warren - fastfwd@ix.netcom.com
=== Fast Forward Engineering - Vista, California
=== http://www.geocities.com/SiliconValley/2499

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