Andres Djordjalian wrote:
>
> > From:          Shane Nelson <i@CHEETAH.SPOTS.AB.CA>
> > Subject:       clock code challenge:
> > Hi,
> > After having seen the amazing results from other code challenges
> > I thought I would try putting one out there myself.
> > 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.
>
> ; BCD clock code challenge
> ; WARNING: This code is not tested
> ;
> ; The regs must be allocated so that a certain bit is set only for
> ; the hours, for example:
>
> seconds EQU     20
> minutes EQU     21
> hours   EQU     22
> #define hoursFlag               FSR,1
>
> ClockTick:      MOVLW   seconds
> loop:           MOVWF   FSR
>                         INCF            INDF,f
>                         MOVLW   6

 Actually, the next two lines should be deleted. You don't
 want to check for 3 rolling over to 4 if this is the hour's
 pass through the loop. Especially since the roll over from
 23 to 24 is checked a few lines below.

>          xxxxxxxxxxxxxx               BTFSC   hoursFlag
>          xxxxxxxxxxxxxx               MOVLW   11

>                         ADDWF   INDF,f
>                         BTFSS   STATUS,DC
>                         SUBWF   INDF,f
>                         MOVLW   60
>                         BTFSC   hoursFlag
>                         MOVLW   24
>                         SUBWF   INDF,W
>                         BTFSS   STATUS,C
>                         RETURN
>                         CLRF            INDF
>                         INCF            FSR,W
>                         BTFSS   hoursFlag
>                         GOTO            loop
> ; This last instruction is not necessary if the code that's executed
> ; after the routine follows, in that case the "RETURN" of a fwe lines
> ; above should be a "GOTO..."
>                         RETURN