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 RAA16518; Wed, 14 Nov 2001 17:05:27 +0100 (MET) 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 RAA11637 for ; Wed, 14 Nov 2001 17:05:26 +0100 (MET) Received: from relay.rinet.ru (relay.rinet.ru [195.54.192.35]) by nez-perce.inria.fr (8.11.1/8.10.0) with ESMTP id fAEG5PL21943 for ; Wed, 14 Nov 2001 17:05:25 +0100 (MET) Received: (from uucp@localhost) by relay.rinet.ru (8.11.6/8.11.6) with UUCP id fAEG5Lk03266 for caml-list@inria.fr; Wed, 14 Nov 2001 19:05:21 +0300 (MSK) X-Envelope-To: caml-list@inria.fr Received: from bely.stormoff (BELY) [192.168.0.10] by stormoff with esmtp (Exim 2.05 #1 (Debian)) id 1642U7-0005PZ-00; Wed, 14 Nov 2001 19:01:55 +0300 X-Comment-To: "Marcin 'Qrczak' Kowalczyk" To: caml-list@inria.fr Subject: Re: [Caml-list] camlidl and pointer to function References: <3BF23EE4.BB444C5C@crf.canon.fr> <9stni6$hh6$1@qrnik.zagroda> From: Dmitry Bely Date: 14 Nov 2001 19:02:59 +0300 In-Reply-To: Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.4 (Civil Service (Windows)) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk "Marcin 'Qrczak' Kowalczyk" writes: > > The problem is that C library is binary-only (Intel image processing > > library), and CallBack type is exactly > > > > typedef int (*CallBack)(int); > > Converting a function closure to a C function pointer can't be done > portably, but it can be done with lots of ugly magic. > > Glasgow Haskell does this (by generating a piece of assembler on > the heap) and it's convenient to use from the level of Haskell. > Such functions need to be explicitly freed of course. > > GNU C does this for local functions, but only "downwards". If the > function pointer doesn't need to live longer than the function which > installs the callback, the GNU C extension can be used. It generates > the piece of assembler on the stack. To use it - just define a function > inside a function and take its address. Hmm, this trick assumes that the stack is executable (IMHO, the serious security hole). Don't know about Linux/x86 page/segment attributes policy, but I am almost sure that Windows NT/2000 x86 (which is my platform) will not allow to execute the code in data/stack pages. > It would be nice if OCaml provided this functionality because not > all C libraries provide the extra argument for simulating closures. > Unfortunately it can't be implemented nicely. > > I've once seen a C library which tries to provide it for several > platforms but I forgot its name. It would be nice if you recall it :-) Hope to hear from you soon, Dmitry ------------------- Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr