Re: Ada to C translator for small microcontrollers

[kalvin.news@gmail.com]

lauantaina 31. maaliskuuta 2012 22.52.03 UTC+3 Rugxulo kirjoitti:
> Hi,
> 
> On Mar 31, 10:46 am, kalvin.n...@gmail.com wrote:
> > keskiviikkona 28. maaliskuuta 2012 19.36.37 UTC+3 Niklas Holsti kirjoitti:
> >
> > > It is true that C does not provide all the features of assembly
> > > language, for all that it is called a "portable assembler". But I'm not
> > > sure that this would be a large handicap for an Ada compiler that uses C
> > > as an intermediate language (like the SofCheck one).
> >
> > > The C level could be a performance bottleneck if one wanted to support
> > > wider numbers in Ada than the C compiler supports -- for example, an Ada
> > > 64-bit Long_Integer with a C compiler that supports only 32-bit integers
> > > -- but this is a marginal effect, I think.
> >
> > Yes, the translator should be implemented so, that it would be compatible with the target C ie. no
> > support for 64-bit integers etc. if the target C compiler doesn't support that.
> 
> If you stick to standard C, that shouldn't be a problem. C99 supports
> "long long" (64-bit), and even GCC has supported it for longer than
> that. Besides, it's probably? fairly trivial to hack up similar
> support with only 32-bit ints. (I know there was a small section an
> AMD manual which showed the basic arithmetic in assembly for such
> operations.)
> 
> > Nested procedures are also a bit tricy to implement in C, as the local stack frame needs to made
> > visible to the inner procedure. This is doable with the struct of pointers passed as parameters for
> > the "inner procedure", I guess. It is up to target C compiler optimization how much penalty there will be.
> 
> GCC supports nested procedures. Something like p2c (Pascal to C) had
> some weird workaround to support it in generic C, too. I imagine that
> using p2c is preferable to writing from scratch in C, though I know
> Pascal isn't quite Ada (but still less painful, no?).
> 
> Anyways, it may be easier to just use an interpreter, something like
> old NYU Ada/Ed, which was written in C, but I haven't ever looked
> close enough nor tried to recompile it. In other words, I don't know
> how portable that C code is, it was (AFAIK) 16-bit for an old Intel C
> compiler. Perhaps someone in this newsgroup has recompiled it before,
> who knows. I realize that's not native speed, but it's probably not
> too bad. It certainly is better than nothing.

P2C (Pascal-to-C) might also be a viable starting point for the translator. However, in order to take advantage of mature GNAT compiler front-end, the GCC looks tempting path. GCC seems to be quite complicated beast, but maybe it can be tamed for the purpose.