OpenEuphoria

Re: 2.4 Official Release - machine level exception

• Posted by Robert Craig <rds at RapidEuphoria.com> Jul 09, 2003
• 537 views

Pete Lomax wrote:
> I get a machine-level exception during the statement
> 	pos[P_yto]-=rely
> where
> 	pos = {24646,7901,32476,9990}
> 	rely = -3543
> 	and P_yto is the constant 4
> 
> If I just insert eg 'if integer(rely) then end if' before that
> statement it works fine.
> 
> Worrying.
> 
> If making such a tiny alteration makes the problem go away, it will
> probably work fine on most other machines (or any with a slightly
> different kernel32.dll etc)...
> 
> Any ideas?

Your little code fragment above works fine for me.
I assume it's part of a much bigger program that
has pokes, calls to C routines etc.
Chances are, you have gone out of bounds with a poke,
passed a bad value to a C routine, etc. The program
could work fine on one run, but fail mysteriously
on another, after any kind of trivial and
seemingly irrelevant change. In this particular case
you may be clobbering a Euphoria variable, stored
in memory near one of your allocated blocks. Perhaps this
is showing up now with 2.4, since the memory is organized
differently. When using Win32Lib, I think you are now
more likely to trash a Euphoria variable when you
go out of bounds, rather than trashing another
memory block that you allocated.

I would at least try safe.e (see instructions at top of safe.e).
Since Win32Lib has gone back to using Euphoria's allocate(),
safe.e is now more effective. By default, in 2.4 Official,
safe.e will only check the edges of blocks allocated
by allocate(), so you shouldn't get any false alarms,
but a lot of memory accesses will not be checked.

Regards,
    Rob Craig
    Rapid Deployment Software
    http://www.RapidEuphoria.com