From patchwork Fri Jan 20 09:17:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bharata B Rao X-Patchwork-Id: 9527845 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 1A66860459 for ; Fri, 20 Jan 2017 09:32:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0BEAD2841D for ; Fri, 20 Jan 2017 09:32:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0054528595; Fri, 20 Jan 2017 09:32:37 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 687422841D for ; Fri, 20 Jan 2017 09:32:37 +0000 (UTC) Received: from localhost ([::1]:53336 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cUVYh-0000wz-S9 for patchwork-qemu-devel@patchwork.kernel.org; Fri, 20 Jan 2017 04:32:35 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34191) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cUVKh-0006BC-IQ for qemu-devel@nongnu.org; Fri, 20 Jan 2017 04:18:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cUVKc-0004Z8-IJ for qemu-devel@nongnu.org; Fri, 20 Jan 2017 04:18:07 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:35808 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cUVKc-0004Y8-Cj for qemu-devel@nongnu.org; Fri, 20 Jan 2017 04:18:02 -0500 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v0K9DhWa121205 for ; Fri, 20 Jan 2017 04:18:00 -0500 Received: from e28smtp06.in.ibm.com (e28smtp06.in.ibm.com [125.16.236.6]) by mx0b-001b2d01.pphosted.com with ESMTP id 283fpgg8f7-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 20 Jan 2017 04:17:59 -0500 Received: from localhost by e28smtp06.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Fri, 20 Jan 2017 14:47:55 +0530 Received: from d28relay06.in.ibm.com (d28relay06.in.ibm.com [9.184.220.150]) by d28dlp03.in.ibm.com (Postfix) with ESMTP id 8DA301258061; Fri, 20 Jan 2017 14:49:32 +0530 (IST) Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay06.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v0K9HsaL19595494; Fri, 20 Jan 2017 14:47:54 +0530 Received: from d28av01.in.ibm.com (localhost [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v0K9HrNM026119; Fri, 20 Jan 2017 14:47:54 +0530 Received: from bharata.in.ibm.com ([9.79.205.184]) by d28av01.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id v0K9HqIW026089; Fri, 20 Jan 2017 14:47:52 +0530 From: Bharata B Rao To: qemu-devel@nongnu.org Date: Fri, 20 Jan 2017 14:47:46 +0530 X-Mailer: git-send-email 2.7.4 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17012009-0020-0000-0000-000000A984A6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17012009-0021-0000-0000-000002644075 Message-Id: <1484903866-17940-1-git-send-email-bharata@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-01-20_06:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=4 spamscore=4 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=1 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1701200135 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.158.5 Subject: [Qemu-devel] [RFC PATCH v1] softfloat: Add round-to-odd rounding mode X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, nikunj@linux.vnet.ibm.com, qemu-ppc@nongnu.org, Bharata B Rao , david@gibson.dropbear.id.au, rth@twiddle.net Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Power ISA 3.0 introduces a few quadruple precision floating point instructions that support round-to-odd rounding mode. The round-to-odd mode is explained as under: Let Z be the intermediate arithmetic result or the operand of a convert operation. If Z can be represented exactly in the target format, the result is Z. Otherwise the result is either Z1 or Z2 whichever is odd. Here Z1 and Z2 are the next larger and smaller numbers representable in the target format respectively. Signed-off-by: Bharata B Rao --- Changes in v1: - Addressed rounding to infinity in roundAndPackFloat128(). - Added 64bit round to odd implementation(roundAndPackFloat64()) as it is needed by xscvqpdp instruction of Power ISA 3.0. v0: http://patchwork.ozlabs.org/patch/716956/ fpu/softfloat.c | 10 ++++++++++ include/fpu/softfloat.h | 2 ++ 2 files changed, 12 insertions(+) diff --git a/fpu/softfloat.c b/fpu/softfloat.c index c295f31..b9b36ad 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -623,6 +623,9 @@ static float64 roundAndPackFloat64(flag zSign, int zExp, uint64_t zSig, case float_round_down: roundIncrement = zSign ? 0x3ff : 0; break; + case float_round_to_odd: + roundIncrement = (zSig & 0x200) ? 0 : 0x3ff; + break; default: abort(); } @@ -1149,6 +1152,9 @@ static float128 roundAndPackFloat128(flag zSign, int32_t zExp, case float_round_down: increment = zSign && zSig2; break; + case float_round_to_odd: + increment = !(zSig1 & 0x1) && zSig2; + break; default: abort(); } @@ -1168,6 +1174,7 @@ static float128 roundAndPackFloat128(flag zSign, int32_t zExp, if ( ( roundingMode == float_round_to_zero ) || ( zSign && ( roundingMode == float_round_up ) ) || ( ! zSign && ( roundingMode == float_round_down ) ) + || ( roundingMode == float_round_to_odd ) ) { return packFloat128( @@ -1215,6 +1222,9 @@ static float128 roundAndPackFloat128(flag zSign, int32_t zExp, case float_round_down: increment = zSign && zSig2; break; + case float_round_to_odd: + increment = !(zSig1 & 0x1) && zSig2; + break; default: abort(); } diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h index 842ec6b..8a39028 100644 --- a/include/fpu/softfloat.h +++ b/include/fpu/softfloat.h @@ -180,6 +180,8 @@ enum { float_round_up = 2, float_round_to_zero = 3, float_round_ties_away = 4, + /* Not an IEEE rounding mode: round to the closest odd mantissa value */ + float_round_to_odd = 5, }; /*----------------------------------------------------------------------------