Hi Rich.

incf FSR,F will destroy zero flag.
Let's try to use incfsz FSR,F instead.

WBR Dmitry.


PS. modified variant of your code:

; given address of 32 bit little-endian counter in W,
; decrement the counter and return Z set if zero
; 99.2% of the time, this takes 10 cycles w/call

dec32:
        movwf   FSR
        decfsz  INDF,F
        goto    dec32nz

        incf    FSR,F
        movfw   INDF

        incf    FSR,F
        iorwf   INDF,W

        incf    FSR,F
        iorwf   INDF,W  ;get _Z finally
        return

dec32nz:
        clrz            ;set _Z=0
        incfsz  INDF,W
        return

        incfsz  FSR,F   ;doesn't corrupt _Z
        decfsz  INDF,F
        incfsz  INDF,W
        return

        incfsz  FSR,F   ;...
        decfsz  INDF,F
        incfsz  INDF,W
        return

        incfsz  FSR,F   ;...
        decfsz  INDF,F
        return
        return