From mboxrd@z Thu Jan  1 00:00:00 1970
Received: (from majordomo@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id FAA18878; Mon, 12 Jul 2004 05:39:31 +0200 (MET DST)
X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f
Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id FAA18604 for <caml-list@pauillac.inria.fr>; Mon, 12 Jul 2004 05:39:29 +0200 (MET DST)
Received: from mproxy.gmail.com (rproxy.gmail.com [64.233.170.205])
	by nez-perce.inria.fr (8.12.10/8.12.10) with SMTP id i6C3dSEV021826
	for <caml-list@inria.fr>; Mon, 12 Jul 2004 05:39:28 +0200
Received: by mproxy.gmail.com with SMTP id d19so318428rnf
        for <caml-list@inria.fr>; Sun, 11 Jul 2004 20:39:16 -0700 (PDT)
Received: by 10.38.9.62 with SMTP id 62mr117890rni;
        Sun, 11 Jul 2004 20:39:16 -0700 (PDT)
Message-ID: <d849ad2a04071120394ea28021@mail.gmail.com>
Date: Sun, 11 Jul 2004 23:39:16 -0400
From: John Prevost <j.prevost@gmail.com>
To: ayerkes@speakeasy.net
Subject: Re: [Caml-list] Toplevel crashes when trying to call external functions
Cc: caml-list@inria.fr
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
X-Miltered: at nez-perce with ID 40F207F0.001 by Joe's j-chkmail (http://j-chkmail.ensmp.fr)!
X-Loop: caml-list@inria.fr
X-Spam: no; 0.00; prevost:01 prevost:01 caml-list:01 crashes:01 non-caml:01 curses:01 initscr:01 curses:01 non-caml:01 opaque:01 caml's:01 pointers:01 camlparam:01 camlreturn:01 mng:99 
Sender: owner-caml-list@pauillac.inria.fr
Precedence: bulk

You shouldn't have to package up a non-caml managed pointer in any
sort of caml structure at all.  Take a look at section 18.6 of the
manual, specifically the definitions of curses_initscr and
curses_wrefresh.  Any pointer that's outside the caml heap (that is,
pretty much any pointer that you're getting from a non-caml function)
can simply be treated as opaque, and you can use Caml's type system to
make sure it's valid (as long as the C code always handles these
pointers correctly.)

I'd write your code like the following, based on that:

Caml code:
type sat_manager
external zchaff_InitManager : unit -> sat_manager
external zchall_ReadCnf : sat_manager -> string -> unit

C++ code:
value zchaff_InitManager(void)
{
  CAMLparam0();
  CAMLreturn((value) SAT_InitManager());
}

void zchaff_ReadCnf(value mng, value filename)
{
  CAMLparam2(mng, filename);
  SAT_Manager solver = (void*)mng;
  cout<<"solver = "<<hex <<solver <<endl;
  assert(solver != NULL);  
  char * fn = String_val(filename);  
  cout<<"file = "<<fn <<endl;
  read_cnf(solver, fn);
  CAMLreturn0;
}

One thing I wonder about, though, is the line:

  SAT_Manager solver = (void*)mng;

shouldn't you be casting to something other than (void*) here?  Not
that I know anything about how the type SAT_Manager is represented.

John.

-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners