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 61E8AC2BA4C for ; Wed, 26 Jan 2022 08:53:37 +0000 (UTC) Received: from localhost ([::1]:44720 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nCe3c-00029p-BW for qemu-devel@archiver.kernel.org; Wed, 26 Jan 2022 03:53:36 -0500 Received: from eggs.gnu.org ([209.51.188.92]:53978) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nCdzb-0000Dg-6B for qemu-devel@nongnu.org; Wed, 26 Jan 2022 03:49:27 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:41968) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nCdzV-0003jU-1a for qemu-devel@nongnu.org; Wed, 26 Jan 2022 03:49:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643186913; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=O2RWSpy6J6R0DhgcBUhrNPF9OYUL2WJbwYquq17Mf+0=; b=fwcrd7irw+wRM//fQEOn0MSiU7F56th21imbohBSY1gmxyfnsL+bKqAmIZxxFr5q6VNvr3 z9CScQJMCJj5AbyyGb2pq8v8NBHKU7uYMISKFICPSWFjDpT0pjEeQnDpuuqmx0C+nw5a6W MkESPYPysC0d4pt48ldU+bAf9GBwBXU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-294-QqI5vfYzP-a78CNHIoWb8A-1; Wed, 26 Jan 2022 03:48:29 -0500 X-MC-Unique: QqI5vfYzP-a78CNHIoWb8A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B407183DEAA; Wed, 26 Jan 2022 08:48:28 +0000 (UTC) Received: from sirius.home.kraxel.org (unknown [10.39.193.47]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 31D1F66E00; Wed, 26 Jan 2022 08:48:27 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id D916018000AA; Wed, 26 Jan 2022 09:48:25 +0100 (CET) Date: Wed, 26 Jan 2022 09:48:25 +0100 From: Gerd Hoffmann To: Volker =?utf-8?Q?R=C3=BCmelin?= Subject: Re: [PATCH v2 01/15] audio: replace open-coded buffer arithmetic Message-ID: <20220126084825.uybvjg427lbjjc3y@sirius.home.kraxel.org> References: <20220122125745.5037-1-vr_qemu@t-online.de> <7976963.x2vcT3psHa@silver> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kraxel@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=kraxel@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.155, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , Christian Schoenebeck , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi, > > > --- a/audio/audio_int.h > > > +++ b/audio/audio_int.h > > > @@ -266,6 +266,12 @@ static inline size_t audio_ring_dist(size_t dst, size_t src, size_t len) > > > return (dst >= src) ? (dst - src) : (len - src + dst); > > > } > > You haven't touched this function, but while I am looking at it, all function > > arguments are unsigned. So probably modulo operator might be used to get rid > > of a branch here. > > That would be "return (len - dist + pos) % len;" but on my x86_64 system I > always prefer a conditional move instruction to a 64 bit integer division > instruction. Why? Performance? Don't underestimate the optimizer of a modern compiler. In many cases it simply isn't worth the effort. Better optimize the code for humans, i.e. make it easy to read and understand. take care, Gerd