On Wed, 14 Jan 1998 23:57:38 -0600 John Payson <supercat@MCS.NET> writes:
>If you can spare another register which holds the value (2diff) and you
>use the same value of "diff" a lot, you could use:
>
>        ; First get the difference
>        movf    x,w
>        subwf   y,w
>        ; Now see if it's in the range -diff..diff
>        addwf   diff,w                  ; i.e. in 0..2diff
>        subwf   diff2,w                 ; If was in range, result >= 0
>
>Perhaps more of a sacrifice than a known-zero register, but I don't
think
>you can do it in four cycles any other way.

    Cute!   Only 6 instructions after the conditional test is appended.
Very useful in the target application.   It is worth the couple extra
instructions of overhead to initialize the 2DIFF register, since there
are many tests with the same DIFF value.

Thanks for the suggested algorithms!
   Jen :-)