Yes this is quite hard.

I find it easier to show the state of the flags in a table, consider:

movfw X
subwf Y,w

This subtracts X from Y and leaves the result in W.

Now look at flags for the compare operations:

X<Y       C=1, Z=0
X<=Y     C=1  Z=Don't Care
X==Y     C=1 Z=1
X>=Y     C=0 Z=Don't Care
X>Y       C=0, Z=0
X!=Y      Z=1

Hope this helps! (Mind you it would have been easier if Microchip had simply
put the logic in Hardware to "correct" the carry flag after a subtraction !

Robin Abbott - robin.abbott@dial.pipex.com

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----- Original Message -----
From: Tony Nixon <Tony.Nixon@ENG.MONASH.EDU.AU>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: 30 September 1999 01:59
Subject: Compares


> Hi all,
>
> I don't know why, but I "still" get confused when doing things like this
> in assembler.
>
>    if RAMx > RAMy then
>
> I just can't seem to keep in my mind what is needed especially when a
> SUBLW instruction is involved.
>
> So, to make it easier on myself and others, I've posted a small text
> file which lists probably all the variations for basic number
> comparisons in 8 and 16 bit format. There are two sets, one give a true
> branch and the other gives a false branch.
>
> If anyones interested, the link is
>
> http://www.picnpoke.com/projects/compares.txt
>
> --
> Best regards
>
> Tony
>
> http://www.picnpoke.com
> Email sales@picnpoke.com