Re: Ada automatic code generation for Simulink models

[Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>]

John Kern <jkern3@NOSPAM.visteon.com> writes:

> I guess what your are saying is to go ahead and allow code generators to
> use the "Universal Assembly" language, and use Ada for only the parts
> that cannot be modeled.  The auto industry is endeavoring to model the
> whole ECU in either Simulink or UML, leaving no room or need for
> generated Ada code.  

What you are saying is that people are using Simulink or UML as the
source code, rather than C or Ada. There are real reasons for this;
controls engineers like to think in graphical diagrams. I think we
need to focus on getting the MathWorks and UML tool vendors to
appreciate the features of Ada that we like, and get them integrated
into Simulink and UML.

> However we still get bogged down with the standardization 

Standardization of what? The graphical modeling language? yes, that is
a problem, and a reason to use Ada instead of a graphical modeling
language. UML is a standard, but the standard language is _not_
powerful enough to generate a whole system, so people use non-standard
extensions.

Improving the UML standard is the best way forward from here;
hopefully, it will incorporate some of the software engineering
features of Ada.

> and modeling of the tasking kernel, 

If it's not an Ada kernel, you have this problem anyway.

> the unsafe C constructs 

What do you mean, precisely, by "unsafe"? Usually, in the context of
"writing C code", this means "constructs that are easily mis-used,
leading to maintenance problems". That's irrelevant if Simulink or UML
is the source language. 

Of course, there may be "unsafe Simulink constructs" or "unsafe UML
constructs". That would be a reason for using Ada instead, or for
fixing the Simulink or UML languages.

> and MISRA compliance, 

Don't know what this is; some industry standard, I guess.

> weak typing 

C weak typing or Simulink weak typing? C weak typing you don't care
about. Simulink weak typing is a problem (I haven't used it, so I
don't really know if it is weak). I believe UML has fairly strong
typing; on a par with C++ (not quite as good as Ada, but not "weak").

> and the representations of variables, etc. 

I can imagine that defining a "type" in Simulink or UML that matches
some hardware register would be hard, if not impossible.

> which didn't seem to be that big a problem when using Ada.

If the Simulink generated Ada, you still wouldn't be able to define a
Simulink "type" that matched hardware registers. Simulink is _not_
going to generate a representation clause for a bit-mapped record type.

If Simulink did let you define a bit-mapped hardware register, it
could generate a bit-mapped C struct, and hope the C compiler has a
"pack structs" flag; most do. So generated Ada would still not be
necessary. 


Make sure you are fighting the right battle; you need Simulink to be
more like Ada, not just Simulink to generate Ada.

-- 
-- Stephe