Re: Ada to C translator for small microcontrollers

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 12-03-26 15:48 , Tomi Saarnio wrote:
> Hi all,
>
> As there exists at least one free decent C cross-compiler for smaller
> 8-bit and 16-bit architectures (Pic, Avr, 8051 etc.), but none Ada
> compiler that I know of,

A partial port of GNAT for the AVR exists: 
sourceforge.net/apps/mediawiki/avr-ada/.

> I was wondering whether there is a demand for
> an Ada to C translator, that would implement some sort of Ada subset
> and output corresponding ANSI C source code.

SofCheck (www.sofcheck.com) provides such an Ada (95) compiler, a 
version of their AdaMagic front-end.

> I am not a compiler or
> Ada expert, so I cannot really estimate the effort how hard this would
> be.

Quite large, I think, unless you take a very small subset. But one would 
really like the subset to provide most of the compile-time advantages of 
Ada: packages, user-defined types, type attributes, generics.

I think the realistic approach for an open-source implementation would 
be to take the existing GNAT front-end and try to generate C code from 
the intermediate representation, either the gcc IR or the llvm IR.

> As far as I can see the problem, the first thing is to identify a
> suitable subset(s) to be implemented, and then to come up with the
> corresponding C source idioms.

In the GNAT-based approach that I suggest above, the bottleneck is in 
the IR-to-C translator. I don't know much about the gcc or llvm IRs, but 
I would expect the subset to be defined by the limitations of whatever 
IR-to-C translator is created, and it may not be easy to define the 
corresponding subset on the Ada level. In any case, it seems simpler to 
start building an IR-to-C translator and accept whatever limitations it 
turns out to have.

There are some "Ada to C/C++" translators that work on the pure 
source-to-source "idiom" basis, but I believe they are intended to help 
porting Ada projects from Ada to C or C++, and probably require manual 
assistance to finish the translation. The SofCheck tool is a fully 
automatic, real compiler that generates complete and finished C source.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
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