I'm very confused here.

By XOR'ing DATA1 with W - you are putting 0000 0000 into DATA3, is that correct?

If DATA0 IN = 1111 1111 and you want after processing DATA0 OUT to = 111 0 AAA,

Then why not mask the bottom 4 bits off with b' 1110 000 then
use an intermediate register an copy DATA1 into it and again mask that off with b' 1110 0000
Then SWAPF DATA0, OR DATA0 and DATA1_copy together and SWAPF again?

If the bottom bits of DATA0 are still needed, then use a DAT0_copy register here as well.

I think if you need to RLF you need to use copy registers. It might be easier if you used a circular buffer, and rotated via FSR.

Colin

:: The data wil be send serial true some MCU pin using a DCC
:: TrainControl
:: Booster.
:: This pattern is generated in the Booster:
:: ; 1111111111   0  AAAAAAAA     0   DDDDDDDD    0   EEEEEEEE    1
:: ;    DATA0     0    DATA1      0    DATA2      0     DATA3     1
::
:: And the result i need for testing must be:
:: ; '1111 0 AAA'    'AAAAA0DD'   'DDDDDD0E'     'EEEEEEE1'
:: ;    DATA0           DATA1        DATA2          DATA3
::
:: I tryed this code allready but i seem to mis some bts during
:: prosessing:
::                bsf                NEW_PACKET                ;*new
:: packet
:: received
::                bcf                DCC4BYTE                ;*if set
:: there is a
:: 4 byte packet
::                movlw        b'11111111'
::                movwf        DATA0                        ;*Set
:: preamble
::                movlw        b'11111111'
::                movwf        DATA1                        ;*Set
:: Byte One
::                movlw        b'11111111'
::                movwf        DATA2                        ;*Set
:: Byte Two
::                xorwf        DATA1, W
::                movwf        DATA3                        ;*Set
:: Byte Three
::                rlf                DATA3, f
::                rlf                DATA2, f
::                rlf                DATA1, f
::                rlf                DATA0, f
::                rlf                DATA00,f
::                rlf                DATA2, f
::                rlf                DATA1, f
::                rlf                DATA0, f
::                rlf                DATA00,f
::                rlf                DATA1, f
::                rlf                DATA0, f
--
cdb, colin@btech-online.co.uk on 10/08/2008
 
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