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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: New GNAT ports (was Re: Ada and Automotive Industry)
Date: 1996/12/24
Message-ID: <dewar.851455793@merv>#1/1
X-Deja-AN: 205827031
organization: New York University
newsgroups: comp.lang.ada
Date: 1996-12-24T00:00:00+00:00
List-Id: <comp.lang.ada>


obert Eachus says

  >"   Amen!  If it wasn't clear before, that was exactly my point.  The
  >cost of the port can be academic if you can't guarantee that the
  >compiler will be ready in time.  I'd want a lot of time for an 8051
  >GNAT target, but for many other potential targets (especially if gcc
  >has already been ported) it is possible to get something up and
  >running in a week.  You may spend the next several months getting it
  >thoughly wrung out and tested, getting the some of the annex support
  >working, building high-level bindings to OS specific libraries, etc.,
  >but without much schedule risk involved.  (In case that last part is
  >confusing, there are parts of the annexes that you can spend a lot of
  >time on if you care, for example Interfaces to COBOL, or tweaking the
  >numerics performance.  But there shouldn't be any schedule risk early
  >in a project from that.  Most of the GNAT annex code ports with the
  >compiler with no extra effort.)"


I would amend that slightly to say "get something up and running in a week",
if you do not include tasking. The tasking may be easy if you have a system
that is very close to Posix compliant, but in our experience there are lots
of variations in threads packages that complicate this task, and I would
more comfortably restrict the "in a week" to exclude tasking.

Also, this is assuming everything goes smoothly, and depends on the quality
of the GCC port, and also how unusual the machine is. GNAT tends to excercise
some aspects of a port which are not excercised by GNU C, and so you can find
that a port needs more work than you thought.

Still the bottom line is certainly that GNAT technology can be ported much
more rapidly than other technologies which require a new code generator to
be written.