Re: Passing Ada Proc as a C Function Pointer

[Warren <ve3wwg@gmail.com>]

On Aug 4, 8:42 pm, Warren <ve3...@gmail.com> wrote:
..
> OTOH, I could create a Thread_Context that is larger than what
> the C routines expect. The Ada side will always be the one
> setting aside the Context and Stack space. So I suppose I could
> stuff an Ada procedure access (ptr) in it, and have a
> C convention proc (in Ada) invoke that, acting as the
> trampoline.  It just wastes a little more space but is
> simple to do.

Crap! That won't work either because the thread starting up
doesn't know its own context object location.  At least with
the current avr_threads API ;-)

I was trying to avoid modifying the avr_thread code. What it
really needs is a user_data parameter.

Hmmmm...

It seems it boils down to 3 choices:

1) Have the starting thread signal the called thread, when it has
"launched".
2) Add a "avr_get_current_thread" routine to return the current
context object.
3) Add a "avr_start_ada_thread" function, which provides the context
object as one of the local_proc arguments. The it can thunk with a
call to context.ada_access_ptr.all;

Only #1 works without changing the avr_threads C library.  Maybe I'll
try that approach first.

Warren