From owner-svn-src-head@FreeBSD.ORG Tue Aug 31 20:22:02 2010 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6456910656F3; Tue, 31 Aug 2010 20:21:59 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 0CD618FC08; Tue, 31 Aug 2010 20:21:59 +0000 (UTC) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id A60EC46B46; Tue, 31 Aug 2010 16:21:58 -0400 (EDT) Received: from jhbbsd.localnet (smtp.hudson-trading.com [209.249.190.9]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id D16118A03C; Tue, 31 Aug 2010 16:21:57 -0400 (EDT) From: John Baldwin To: Dimitry Andric Date: Tue, 31 Aug 2010 16:21:47 -0400 User-Agent: KMail/1.13.5 (FreeBSD/7.3-CBSD-20100819; KDE/4.4.5; amd64; ; ) References: <201008311811.o7VIBoC5037894@svn.freebsd.org> <201008311537.51825.jhb@freebsd.org> <4C7D5DD2.40407@FreeBSD.org> In-Reply-To: <4C7D5DD2.40407@FreeBSD.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201008311621.48087.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Tue, 31 Aug 2010 16:21:57 -0400 (EDT) X-Virus-Scanned: clamav-milter 0.95.1 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.6 required=4.2 tests=AWL,BAYES_00 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r212064 - head/sys/boot/pc98/boot2 X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 31 Aug 2010 20:22:02 -0000 On Tuesday, August 31, 2010 3:53:54 pm Dimitry Andric wrote: > On 2010-08-31 21:37, John Baldwin wrote: > >> - return *(p + 0x401) * 128 * 1024 + *(u_int16_t *)(p + 0x594) * 1024 * 1024; > >> + return *p * 128 * 1024 + *(u_int16_t *)(p + (0x594 - 0x401)) * 1024 * 1024; > >> } > > > > Perhaps replace '(p + 0x594 - 0x401)' with just 'PTOV(0x594)'? > > > > I would actually find it cleaner to remove 'p' altogether perhaps: > > > > return (*(u_char *)PTOV(0x401) * 128 * 1024 + > > *(uint16_t *)PTOV(0x594) * 1024 * 1024); > > Yes, I attempted this variation at first, but it made the code bigger, > which I wanted to avoid: it went from "11 bytes available" to "7 bytes" > available. > > I tried several semantically equivalent permutations of the expression, > and the one I committed gave no increase or decrease in code size. > > Apparently the code size produced by gcc is very sensitive to even > minimal changes. For example, a lot of the PTOV() pointer dereferences > should really be qualified with 'volatile', but that even causes boot2 > to become too big to fit! > > If the 4 extra bytes are no problem, then I would be glad to change it > to the above expression, though. It is certainly clearer. :) I would go with cleaner as long as it fits. I would only resort to weird tricks such as the 'p' one used previously if they are actually needed. -- John Baldwin