Not elegant but seven instructions and free:

    movf    X,W             ; get first number.
    subwf   Y,W             ; sub second number.
    bc      AA              ; result positive? - Yes, go to AA.
    xorlw   h'FF'           ; convert from two's compliment
    addlw   1               ;   negative to positive.
AA  subwf   DIFF,w          ; sub difference from DIFF.
    bc      LESS            ; result + or 0? - Yes, goto LESS.


On Tue, 13 Jan 1998 11:49:18 EST, you wrote:

->Happy New Year,
->   I was just wondering if anyone has an elegant method for
determining
->whether two numbers are within an absolute difference, in the 12 bit
PIC
->universe.
->
->  For example...  the two numbers, X & Y, are in registers which
must
->remain unchanged are to be tested to determine whether they are
within
->DIFF of each other.
->
->  My first try this year is:
->
->          MOVF       X,W        ;Try it this way
->          SUBWF   Y,W
->
->          SKPNC                  ; Positive?
->          GOTO      POS      ; Yes
->
->          MOVF       Y,W       ; No, then do it the other way
->          SUBWF   X,W
->
->POS  SUBWF  DIFF,W  ; Compare against the limit
->
->          SKPNC                  ; The carry knows...
->          GOTO     LESS
->
->
->Thanks in advance,
->   Jen :-)