Re: Where is the elusive jump command?

[Ole-Hjalmar Kristensen <ohk@clustra.com>]

kilgallen@eisner.decus.org (Larry Kilgallen) writes:

> In article <umqvh1wnaad.fsf@gong2.clustra.com>, Ole-Hjalmar Kristensen <ohk@clustra.com> writes:
> > Robert Dewar <dewar@gnat.com> writes:
> 
> >> But in any case, binding to C is hardly a topic that is
> >> appropriate to people first learning the language!
> >> 
> > 
> > Certainly, but writing bindings to C is one of the first things you
> > have to do if you start using Ada for systems programming on Unix,
> > unfortunately.
> 
> I am not sure what you mean by "systems programming" in this case.
> I would presume that writing device drivers requires knowledge of
> internal data structures, but don't vendors like Rational supply
> bindings to Unix entrypoints that might be called by user-mode
> programs ?

I was not thinking device drivers, but systems like communications
systems or DBMS's, which typically will need access to Unix
entrypoints or system calls. A thick binding designed by someone who
is unaware of the specific needs of the system may not be suitable.

An example of the the need for system calls: A couple of months ago I
wanted to test various implementations of asynchronous IO (Sun
asynchronous IO, POSIX asynchronous IO, and Ada). However, to do a
meaningful test, I need to ensure that I/O operations on the file
descriptor complete as defined by synchronized I/O data integrity
rules. This means either using the fcntl or fsync system calls, or
setting the O_SYNC flag in the call to open.

In this case, needing only a few system calls, it may be more cost
effective to write your own binding, as it's usually not difficult.

Yes, it may be possible to buy such a binding, although I have not
seen any reference to it, either on Rational's web pages, nor on
Adahome's list of bindings. 

There is a reference to a POSIX binding, but that seems very much to
be a work in progress.

Ole-Hj. Kristensen

-- 
E pluribus Unix