Re: Augusta: An open source Ada 2012 compiler (someday?)

[Brian Drummond <brian3@shapes.demon.co.uk>]

On Thu, 20 Mar 2014 11:35:37 -0700, Shark8 wrote:

> On 19-Mar-14 16:04, Brian Drummond wrote:
>> I strongly believe Ada and VHDL users should talk to each other more
>> than they do!
> 
> Isn't that because VHDL is essentially concerned about hardware and
> [most] programmers are essentially worried about software? 

These days most hardware designers worry about software too. For testing 
and verification, but also much hardware requires software in the form of 
drivers, API, applications, or contains its own CPU and requires embedded 
SW.

Add in the need to verify DSP algorithms, and hardware designers would 
love to see a language that natively supported fixed-point arithmetic.

instead, SystemC adds C++ classes to support user-specified datatypes 
including fixed point and is becoming popular...

There is also the move towards "high level synthesis" that can take code 
developed in a "high level language" meaning some dialect of C (or 
SystemC) and synthesise to hardware, bringing all the benefits of C to 
hardware design.

(now why do I find this depressing?)

>-- That said,
> would if be possible/feasible to have a compiler that takes a VHDL
> description of some architecture and Ada source and compile it to run on
> that architecture?

Not at all easy. An instruction set description of some architecture 
would be much easier - and allow a compiler to target any CPU for which 
such a description can be written.

I am more interested in the synergies between Ada and VHDL as languages. 
For example : 
A decent subset of Ada is nearly identical to VHDL, allowing users to 
switch between them quite painlessly.

The ability to model floating and fixed point and compare accuracy is 
very useful (VHDL doesn't natively support fixed point, but having a 
proven model to port to the fixed point libraries would be very useful)

Despite the long time use of formal tools (eg static timing analysis) in 
HW design, Ada is ahead in formal tools for correctness (SPARK et al)

The Spark restrictions on Ada share quite a lot with the restrictions 
inherent in the synthesisable subset of VHDL. 

High level synthesis techniques developed for other languages should be 
equally applicable to Ada and VHDL.

The only HLS work I know about for Ada is the York Hardware Ada Compiler

http://www.cs.york.ac.uk/ftpdir/reports/2005/YCST/09/YCST-2005-09.pdf

which is an interesting paper, but slightly undermined by the fact that 
the subset of Ada (at least in the published example) is essentially 
synthesisable VHDL!

- Brian