To me it looks more like a BCD to binary  conversion. BCD=16*tens+ones. To
get it on to binary you require 10*tens+ones. so you do a BCD-8*tens+2*tens.

If you happen to get a binary to BCD converter, please forward it to be. I'm
really interested.

PS. It might be possible to get a binary to BCD converter using the same logic.
Am trying to work it out.

At 17:01 4/27/98 +0100, John Midgley wrote:
>Dear All
>
>Cannily realising that I'd want a binary to BCD conversion routine
>in the future, I carefully filed and kept a brief thread on the subject
>from a few weeks ago. Slightly less cannily, I can't understand what
>it's doing. Can anyone point me in the right direction, pseudo-code-
>wise? Let's say I have a byte 'count'; if it can run to FFh, I guess I
>need 12 bytes of BCD (3 lots of 4 bytes?) to encode '255'.  Or would
>it be customary to stop at 63h (99 dec.)? Either way, in English (or some
>approximation) what am I doing? This was the routine:
>
>>     rrf   bcd,W
>>     andlw 01111000b  ;W = tens*8
>>     movwf temp
>>     clrc
>>     rrf   temp,f     ;temp = tens*4
>>     rrf   temp,f     ;temp = tens*2
>>     subwf bcd,W      ;W = tens*16 + ones - tens*8
>>                      ;W = tens*8 + ones
>>     addwf temp,W     ;W = tens*10 + ones
>>
>
>I know what all the opcodes mean, but that's not quite the same as
>understanding the whole thing!
>
>And if I wanted to go to 9999 decimal (270Fh) could I scale it up easily?
>
>Any help greatly appreciated.
>
>Regards
>
>John M
>
>
with best wishes and regards
Sujay Sirur

Email: sirur@giasbg01.vsnl.net.in
Home: 604, Chitrapur Housing Society, Plot no 68, 15th Cross, 8th Main,
Malleshwaram
            Bangalore 560 055. INDIA   Tel. no: 91-80-344-3688

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