[Flashforth-devel] Bug report: Can't write beyond $a300

[Pablo M. M. <ea...@ho...>]

I think I have found a (small) bug.

In FF 3.8 (original) compiled for a 18F2620, trying to write beyond $a300 gives an "AD?" error. 

I have found the problem here:

ISTORECHK:
        movlw    HIGH dpcode ;(dp_user_dictionary>>8) ;
        subwf    Srw, W, A
        btfsc   STATUS, N, A
        bra     ISTORERR
        return

The instruction subwf gives a signed result, and sets N if (Srw) - W > $7f

This can be solved with an unsigned compare:

ISTORECHK:
        movlw    HIGH dpcode ;(dp_user_dictionary>>8) ;
        cpfslt  Srw, A
        return
        bra     ISTORERR

With this change, writes work OK from $2300 to $ebff.

I made this change in order to put the help system at the end of the flash space.


Regards, 

    Pablo.