From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: ludo@gnu.org (Ludovic =?iso-8859-1?Q?Court=E8s?=) Newsgroups: gmane.lisp.guile.devel Subject: Re: ffi docs Date: Tue, 27 Jul 2010 10:24:10 +0200 Message-ID: <87mxtdxrh1.fsf@gnu.org> References: <87ljco1gyc.fsf@ossau.uklinux.net> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: dough.gmane.org 1280219075 11663 80.91.229.12 (27 Jul 2010 08:24:35 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Tue, 27 Jul 2010 08:24:35 +0000 (UTC) To: guile-devel@gnu.org Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Tue Jul 27 10:24:32 2010 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1OdfSe-0006T8-DG for guile-devel@m.gmane.org; Tue, 27 Jul 2010 10:24:28 +0200 Original-Received: from localhost ([127.0.0.1]:41924 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OdfSd-0002mr-Of for guile-devel@m.gmane.org; Tue, 27 Jul 2010 04:24:27 -0400 Original-Received: from [140.186.70.92] (port=42943 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OdfSZ-0002kp-1T for guile-devel@gnu.org; Tue, 27 Jul 2010 04:24:24 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OdfSX-0001od-HY for guile-devel@gnu.org; Tue, 27 Jul 2010 04:24:22 -0400 Original-Received: from lo.gmane.org ([80.91.229.12]:41538) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OdfSX-0001oR-B7 for guile-devel@gnu.org; Tue, 27 Jul 2010 04:24:21 -0400 Original-Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1OdfSU-0006QD-VV for guile-devel@gnu.org; Tue, 27 Jul 2010 10:24:18 +0200 Original-Received: from yoda.fdn.fr ([80.67.169.18]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 27 Jul 2010 10:24:18 +0200 Original-Received: from ludo by yoda.fdn.fr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 27 Jul 2010 10:24:18 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 37 Original-X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: yoda.fdn.fr X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 9 Thermidor an 218 de la =?iso-8859-1?Q?R=E9volution?= X-PGP-Key-ID: 0xEA52ECF4 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 83C4 F8E5 10A3 3B4C 5BEA D15D 77DD 95E2 EA52 ECF4 X-OS: x86_64-unknown-linux-gnu User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) Cancel-Lock: sha1:xD8U8/yZhwry+X2CzgqUj9uYz+8= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:10736 Archived-At: Hi! Neil Jerram writes: >> Void pointers may be accessed as bytevectors. >> >> -- Scheme Procedure: foreign->bytevector foreign [uvec_type [offset >> [len]]] >> -- C Function: scm_foreign_to_bytevector foreign uvec_type offset len >> Return a bytevector aliasing the memory pointed to by FOREIGN. >> >> FOREIGN must be a void pointer, a foreign whose type is VOID. By >> default, the resulting bytevector will alias all of the memory >> pointed to by FOREIGN, from beginning to end, treated as a `vu8' >> array. > > It feels like we're missing a unification trick here. > > Thought #1: if we have, e.g., an int8 pointer ip, why not just use > (foreign-ref ip n) to interpret the pointer as pointing to an array, and > get its nth element? > > Thought #2: but if we do that we'll be duplicating the bytevector API. > So instead, shouldn't the fundamental operation be (foreign->bytevector > NAME TYPE LIBRARY [LEN]), and get/set then done using the bytevector > API? Andy and I discussed it at GHM, which led to this simplification of the API: http://git.savannah.gnu.org/cgit/guile.git/commit/?id=d4149a510e4a87915b625255f4de3301510d810c There are a few more changes coming: renaming some of the procedures from ‘foreign’ to ‘pointer’, and adding more convenience procedures (C string manipulation notably). Thanks, Ludo’.