Keith Burzinski <tsk3000@Prodigy.Net> wrote:

> I am using 'subwf' on a 16C54 to compare two bytes, and I saw in the
> programmers manual how the Carry flag is set... the Zero flag is
> still set according to the result, correct?

    Correct, Keith.

> Really, I'm doing a greater than/less than/equal to thing, so,
> first I should check the Z flag to see if the result was zero, if
> it was, I'll branch, if not, then test the C flag and go from
> there, right?

    Actually, it'll be faster to check the C flag first, then only
    check the Z flag if the C flag was set... That way, you only
    check one flag when the result is negative (a much more-likely
    occurence than a "0" result).

> So, when using 'subwf':
> If (f) - (W) is positive,
>    (f) > (W) / Z = 0, C = 1.
> If (f) - (W) is zero,
>    (f) = (W) / Z = 1, C = 1.
> If (f) - (W) is negative,
>    (f) < (W) / Z = 0, C = 0.
>
> Is everything I said about the flags correct?

    Yes, if you treat the contents of "f" and "w" as unsigned (i.e.,
    non-negative) numbers.

    -Andy

=== Andrew Warren - fastfwd@ix.netcom.com
=== Fast Forward Engineering - Vista, California
=== http://www.geocities.com/SiliconValley/2499