Thank you very much to all that helped me, especially
to Andrew and Dmitriy.
I=B4m going to do some tests to INC/DEC the high byte
using the last example of Dmitriy.

Luis F.


----- Original Message -----=20
From: "Dmitriy Kiryashov" <vze27bym@verizon.net>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Monday, August 01, 2005 6:48 PM
Subject: Re: [PIC]: INC/DEC 2 PACKED BCD NUMBERS


> Hi Andy.
>
> Squeezing the lemon :)
>
> incf reg,F ;INCF    REG
> movlw 0x66 ;MOVLW   0x06
> addwf reg,F ;ADDWF   REG
> skpndc ;SKPDC
> andlw 0xF0 ;SUBWF   REG
> skpnc ;MOVLW   0x60
> andlw 0x0F ;ADDWF   REG
> subwf reg,F ;SKPC
> ;SUBWF   REG ;;btw here Cy is always=3D1
>
>
> movlw 0x01 ;MOVLW   1
> subwf reg,W ;SUBWF   REG
> skpdc ;MOVLW   0x06
> xorlw 0x06 ;SKPDC
> skpc ;XORWF   REG
> xorlw 0x60 ;MOVLW   0x60
> movwf reg ;SKPC
> ;XORWF   REG
>
>
> I think it is in piclist archive somewhere.
>
>
> WBR Dmitry.
>
>
>
> Andrew Warren wrote:
>>
>> Luis:
>>
>> This comes up every once in a while and is likely to be in the
>> archives somewhere.
>>
>> The last time I answered the question, I came up with these.  I
>> didn't assemble or test them, but no one complained that they failed
>> to work...
>>
>> To increment one byte:
>>
>>     INCF    REG
>>
>>     MOVLW   0x06
>>     ADDWF   REG
>>     SKPDC
>>     SUBWF   REG
>>
>>     MOVLW   0x60
>>     ADDWF   REG
>>     SKPC
>>     SUBWF   REG
>>
>> To decrement one byte:
>>
>>     MOVLW   1
>>     SUBWF   REG
>>
>>     MOVLW   0x06
>>     SKPDC
>>     XORWF   REG
>>
>>     MOVLW   0x60
>>     SKPC
>>     XORWF   REG
>>
>> The Carry flag is valid after each of those, so first inc/dec the low
>> byte, then use the carry to decide whether to inc/dec the high byte.
>>
>> -Andy
>>
>> =3D=3D=3D Andrew Warren - fastfwd@ix.netcom.com
>>
>> --
>> http://www.piclist.com PIC/SX FAQ & list archive
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>> http://mailman.mit.edu/mailman/listinfo/piclist
> --=20
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