> -----Original Message-----
> From: WEBB,TIM (A-Sonoma,ex1) [mailto:tim_webb@AGILENT.COM]
> Sent: Wednesday, December 19, 2001 2:58 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [PIC]: Moving from f to f register
>
>
> So I can:
>
>         movwf   f               move w to f
>         movf    f, w    move f to w
>

keep in mind that 'f' has a special meaning if you use the include file
(which you should use): it means the destination is a file register. the
assembler substitues a '1' for the 'f'. In the example, i guess it would
move register #1 (TMR0) to w, then w back to register #1. That's probably
not what you had in mind. If you aren't using the include file, then this
doesn't apply.

> But can I:
>
>         movf    f1, f2    move f1, f2
>
> MPLAB says: Warning[202] Argument out of range.  Least
> significant bits
> used.
>

you can't do this. well, you can, but the results won't be what you
intended. the second argument (f2 in your example) specifies the
destination. However, the destination can only be one of two values: 0 or 1.
a zero means store it in W. a 1 means store it in file register. In the
example, f2 has some address, and the assembler substituted the address of
f2. That of course is illegal, because the destination must be 0 or 1.

> Or do I have to:
>
>         movf    f1, w   move f1 to w
>         movwf   f2              move w to f2
>
> No warnings here....
>

yup, to move one register to another, you have to go through the w register.

here's yet another summary of movf. It assumes you are using the include
file:

        movf    <register>, <destination>

        <register> is the register you want to move. <destination> is where
you want to put the result. *BUT* the <destination> can only be f (1) or w
(0). that means you can move the register to itself, or to the working
register. And that's it. BTW, this information is in the datasheet, it's
just a matter of learning the language. To most of us, it's
self-explanatory. But not to everyone. Hope this clears things up.



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