From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4EB6AD39432 for ; Thu, 2 Apr 2026 14:40:22 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1w8JCv-0001n4-U6; Thu, 02 Apr 2026 10:39:41 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1w8JCs-0001ma-10 for qemu-devel@nongnu.org; Thu, 02 Apr 2026 10:39:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1w8JCq-0007Cz-Gi for qemu-devel@nongnu.org; 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Thu, 2 Apr 2026 14:39:25 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.6]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7746D1800361 for ; Thu, 2 Apr 2026 14:39:25 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id D515321E6A28; Thu, 02 Apr 2026 16:39:22 +0200 (CEST) From: Markus Armbruster To: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Cc: qemu-devel@nongnu.org, Daniel P. =?utf-8?Q?Berrang=C3=A9?= Subject: Re: [PATCH 11/60] ui/console-vc: add UTF-8 input decoding with CP437 rendering In-Reply-To: (=?utf-8?Q?=22Marc-Andr=C3=A9?= Lureau"'s message of "Thu, 2 Apr 2026 15:44:35 +0400") References: <20260317-qemu-vnc-v1-0-48eb1dcf7b76@redhat.com> <20260317-qemu-vnc-v1-11-48eb1dcf7b76@redhat.com> <878qbgpj31.fsf@pond.sub.org> Date: Thu, 02 Apr 2026 16:39:22 +0200 Message-ID: <87se9dtoit.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 7 X-Spam_score: 0.7 X-Spam_bar: / X-Spam_report: (0.7 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.542, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Marc-Andr=C3=A9 Lureau writes: > Hi Markus > > On Wed, Mar 25, 2026 at 10:48=E2=80=AFAM Marc-Andr=C3=A9 Lureau > wrote: >> >> HI >> >> On Wed, Mar 25, 2026 at 9:35=E2=80=AFAM Markus Armbruster wrote: >> > >> > Marc-Andr=C3=A9 Lureau writes: >> > >> > > The text console receives bytes that may be UTF-8 encoded (e.g. from >> > > a guest running a modern distro), but currently treats each byte as a >> > > raw character index into the VGA/CP437 font, producing garbled output >> > > for any multi-byte sequence. >> > > >> > > Add a proper UTF-8 decoder using Bjoern Hoehrmann's DFA. >> > > The DFA inherently rejects overlong encodings, surrogates, and >> > > codepoints above U+10FFFF. Completed codepoints are then mapped to >> > > CP437, unmappable characters are displayed as '?'. >> > > >> > > Signed-off-by: Marc-Andr=C3=A9 Lureau >> > >> > Have you considered the decoder in util/unicode.c? Do we need two >> > decoders, or could we replace one by the other? >> > >> >> Oh! I missed it, I should definitely try to use it. > > The vt100 receives characters one at a time. The DFA is suited for > this. mod_utf8_codepoint() works with whole buffers. It's possible to > write one with the other, but we lose in performance, and we need > extra quirks. I don't think it's worth it. Implementing a buffer interface on top of a character at a time interface should be easier than the other way round. I doubt rewriting mod_utf8_codepoint() to wrap around the DFA would slow things down materially. I'm not demanding you try that! If we decide to go with two decoders, do we want a unit test to ensure they behave the same? [...]