object ada, visual c and tasking combined.

[john donoghue <donoghue@chariot.net.au>]

Hi all,

I have a problem that perhaps someoneelse has encountered before and
found a way around.
Firstly, I have some legacy ada code that amongst other things displays
some stuff on a display via a custom graphics controller board.
Recently it has been decided to upgrade that by replacing the existing
graphics code with a visual c front end.

All well and good, I can build a gui in visual c in several cpp files
and link it in after defining a few pragmas to access the c
functionality  - first problem with objectAda ...
it complains about conflicts between libcd.lib having variables that are
alreadt defined.
And also it complains about linking in some of the visual c dll's etc
and unresolved symbols and more.

After getting sick of that, I decided to try compiling the gui part in
to a dll and link that to the ada code ... hey it works ... but to be
compatible with the old graphics stuff, the dll has to also call a few
ada functions that are within the main ada application ... no problem
... let's send a structure from the ada code to the visual c code on
initialization that contains pointers to the functions that the c code
will need to call later.
... It seems to work ... next problem .... The visual c windowing stuff
is in its own task, and there is also another C task that needs to wait
on an ada function to return with data - but everytime I call the
"pointered" functions from these tasks the app spits the dummy (
terminates with a exception that provides no name or message or
anything. )
I am guessing that you cant call the ada functions from the other C
tasks since they are in other tasks to the ada functions :) ... but is
there a way around it?

Cheers,
  John