From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:56305) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UMTLH-0004EJ-LL for qemu-devel@nongnu.org; Sun, 31 Mar 2013 21:15:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UMTLD-00079W-AX for qemu-devel@nongnu.org; Sun, 31 Mar 2013 21:15:23 -0400 Received: from mail-pa0-f47.google.com ([209.85.220.47]:59353) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UMTLD-00079J-4T for qemu-devel@nongnu.org; Sun, 31 Mar 2013 21:15:19 -0400 Received: by mail-pa0-f47.google.com with SMTP id bj3so1059183pad.34 for ; Sun, 31 Mar 2013 18:15:18 -0700 (PDT) Sender: Richard Henderson Message-ID: <5158DFA2.9080609@twiddle.net> Date: Sun, 31 Mar 2013 18:15:14 -0700 From: Richard Henderson MIME-Version: 1.0 References: <1364687686-6006-1-git-send-email-aurelien@aurel32.net> <5158C491.4010509@twiddle.net> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] target-ppc: fix nego and subf*o instructions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: qemu-devel@nongnu.org, Aurelien Jarno , Alexander Graf On 03/31/2013 04:50 PM, Peter Maydell wrote: >> > I'm a bit confused. This is the exact same algorithm that's used on ARM and >> > i386. And as far as I can determine, all three platforms have the same >> > definition of "overflow". > I think it's not quite the same as ARM because the two arguments > to subtract are reversed for PPC (ie PPC is 'subtract from', not > 'subtract'). I think that means you want 'xor_tl(cpu_ov, arg0, arg2)' > for your first xor, maybe? (untested) Oh, duh. Of course. r~