Re: Converting Ada Tasks To VxWorks Tasks?

[Tucker Taft <stt@averstar.com>]

Michael Hartsough wrote:
> ...
> 
> Semaphores have priority queues, but I haven't figured out a way
> to implement a Select statement that'll use semaphores and be
> able to handle a guarded accept without performing some sort
> of polling.
> 
> Anyways, if anyone can provide me with some references to work that's
> already been accomplished in this area I'd be mighty grateful.

Most Ada run-times are built on just a few low-level primitives of the
underlying system, in part because the required high-level Ada semantics
rarely match exactly the high-level primitives provided by a given
RTOS.  

As far as select statements, these require some relatively complex
data structures built up by the Ada run-time system, plus some
fairly low level signaling primitives (e.g. binary semaphores,
event flags, etc.) provided by the underlying RTOS.

Since the GNAT run-time is open source, you could conceivably
just go and read the implementation for select statements, etc.
and figure out what you need to do.  It is straightforward,
but far from trivial...

I might put in a plug for our Ada 95 compiler that uses optimized ANSI C
as its intermediate language.  This would allow you to
reuse the existing Ada code, and easily interface with
C/C++ code, and give your boss some readable C code to study
when he is curious what you are doing...
  
> 
> Thanks,
>                 MJH

-- 
-Tucker Taft   stt@averstar.com   http://www.averstar.com/~stt/
Technical Director, Distributed IT Solutions  (www.averstar.com/tools)
AverStar (formerly Intermetrics, Inc.)   Burlington, MA  USA