Hello Everyone,

My previous question seems to have gone astray because it still hasn't
appeared on the list after several days. This is good in a way because I have
had a chance to do a little more research and now I almost have the answer.

The follow piece of code, which I borrowed from an anemometer project and
modified to include 16 bit subtraction, is meant to convert a hex number into
a decimal format and display the result on a two line LCD display.

It almost works. The problem is that I have lost the units value (DestL) by
the start of the line that begins with "btfss           STATUS,Z".

I have tried to save the value after the subtraction to a temporary location
but of course that also saves the over-written value as well. I am very much
a beginner and have reached my wit's end. Can someone see how I can get this
going?

Kmail seems to alter the layout of tabbed text so I hope the code is readable
when it arrives on the mailing list.

init    clrf    UNITS
        clrf    TENS
        clrf    HUNDREDS

        movlw   0x10
        movwf   DestL
        movlw   0x00
        movwf   DestH
        movlw   0x0a
        movwf   SourceL
        movlw   0x00
        movwf   SourceH

CnvMax  movf    SourceL,W
        subwf   DestL,1
        movf    SourceH,W
        btfss   STATUS,C
        incfsz  SourceH,W
        subwf   DestH,1         ;dest = dest - source, WITH VALID CARRY

        btfss   STATUS,Z        ; Checks if 10 can be subtracted from ls digit
        goto    PrntMx          ; No, so done and go on
        movwf   UNITS
        incf    TENS,F          ; Yes, so subtract and inc second digit
        movlw   10
        subwf   TENS,W          ; Checks if second digit is greater than 10
        btfss   STATUS,C
        goto    CnvMax
        movwf   TENS
        incf    HUNDREDS,F      ; Yes, so subtract and inc third digit
        goto    CnvMax

PrntMx
        end

--
Regards,
Phil.

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