Array memory allocation

[Mark Newman]

I'm using a DLL function that accepts an integer array from VB, does some
hardware I/O, modifies the VB array and exits. I'm passing the VB array
as outlined in Appendix A of the PB manual, so that should be okay. The
trouble is that the PB DLL function needs to allocate an integer array for
temporary use with the I/O driver; how can I be sure that the local array
memory won't conflict with the passed VB array?

The hardware I/O driver has a debug mode that shows the memory addresses
of the arrays passed to it, and it appears that there is a memory
overlap. If true, I could pass all of the needed arrays from VB to PB, but
that would really gum up the VB code (more than it already is ).

Any ideas?


------------------
Mark Newman

[Tom Hanlin]

Arrays allocated in PB will never overlap with arrays allocated in VB, unless you specifically use the DIM..AT syntax to override this behavior.

------------------
Tom Hanlin
PowerBASIC Staff

[Mark Newman]

Tom,

Thanks for the reply; this is the behavior that I would expect.
I'll keep digging!



------------------
Mark Newman

[Mark Newman]

...um, found it...

I was passing the I/O driver the addresses of the array pointers,
not the addresses of the arrays themselves. Using BYVAL VARPTR(array(0))
instead of VARPTR(array(0)) did the trick.

As a lame defense of this "oversight" I'll add that I was porting
the function declares and function stubs from a VB file to PB
format. Yes, that's it, I'll blame the sometimes-bizarre VB-to-DLL
calling convention...



------------------
Mark Newman