Re: GUI Design for Ada

["Andrew" <mysig@fast.net>]

Thanks everyone for your suggestions.



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Andrew

Ted Dennison <dennison@telepath.com> wrote in message
news:7vcd4p$r9q$1@nnrp1.deja.com...
> In article <7vb03r$1ea$1@news5.fast.net>,
>   "Andrew" <mysig@fast.net> wrote:
>
> > However, the project I'm working on is a multi-process  simulation
> > that runs on a dual PowerPC system.
>
> Out of curiosity, what OS are you using?

PowerMAX OS


> > I'm looking for a good reference/tutorial type book that discusses
> > real-time programming in Ada that's new to this field.
>
> I'm not aware of an Ada book specific to real-time. Chapters 17 and 18
> in Cohen's Ada as a Second Language cover a lot of the issues.
> We also have a couple of copies of A Practitioner's Handbook for
> Real-Time Analysis, which covers a lot of issues related to
> Rate-Monotonic systems in a language-neutral manner.
>
> In Ada you can make a simple rate-monotonic system by putting each
> scheduled item in its own task. Each task should set its priority
> relative to the other tasks to be the same as its iteration rate
> relative to the other tasks (using Ada.Dynamic_Priorities). A global
> package that keeps track of everyone's priority and rate (perhaps as
> read from a configuration file) can be useful for this purpose.
>
> Before its first iteration, each task should save the current value of
> Ada.Real_Time.Clock. At the end of each iteration, the task will add its
> iteration rate to the saved time, and perform a "delay until" that time.
> More sophistacted logic can be added to detect and handle overruns.

we are using IRIG time. The code was originally written in Ada83.

>
> We discovered on our project that with careful attention given to using
> standard Ada constructs rather than their OS equivalents, one can create
> an entire real-time simulation in Ada that is souce code portable to
> other OS/compiler combinations (excepting specialized hardware
> interfaces, of course).

unfortunately, we use OS calls and have an enhanced Ada83 compiler.


   For instance, when hardware availability turned
> out to be a problem, we were able to compile and test early versions of
> our entire system on NT boxes using Gnat, even though the code was
> written for the GreenHills Ada cross-compiler for vxWorks. Of course you
> don't quite get real-time performance in NT. But if we needed to change
> RTOS's or compiler vendors, it would be an almost painless process. I am
> unaware of *any* other language that could provide this.
>
> --
> T.E.D.
>
>
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