{"id":810768,"url":"http://patchwork.ozlabs.org/api/patches/810768/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20170906184133.25524-5-dgilbert@redhat.com/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20170906184133.25524-5-dgilbert@redhat.com>","list_archive_url":null,"date":"2017-09-06T18:41:29","name":"[PULL,4/8] host-utils: Simplify pow2ceil()","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"f227a38719362d3735db7a9d4ca954daa719d7a8","submitter":{"id":48102,"url":"http://patchwork.ozlabs.org/api/people/48102/?format=json","name":"Dr. David Alan Gilbert","email":"dgilbert@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20170906184133.25524-5-dgilbert@redhat.com/mbox/","series":[{"id":1865,"url":"http://patchwork.ozlabs.org/api/series/1865/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=1865","date":"2017-09-06T18:41:26","name":"[PULL,1/8] migration: Report when bdrv_inactivate_all fails","version":1,"mbox":"http://patchwork.ozlabs.org/series/1865/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/810768/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/810768/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; helo=lists.gnu.org;\n\tenvelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n\treceiver=)","ext-mx04.extmail.prod.ext.phx2.redhat.com;\n\tdmarc=none (p=none dis=none) header.from=redhat.com","ext-mx04.extmail.prod.ext.phx2.redhat.com;\n\tspf=fail smtp.mailfrom=dgilbert@redhat.com"],"Received":["from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11])\n\t(using TLSv1 with cipher AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xnXfD4dXnz9sRV\n\tfor ;\n\tThu, 7 Sep 2017 04:48:20 +1000 (AEST)","from localhost ([::1]:37489 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t)\n\tid 1dpfN4-0008Oi-Op\n\tfor incoming@patchwork.ozlabs.org; Wed, 06 Sep 2017 14:48:18 -0400","from eggs.gnu.org ([2001:4830:134:3::10]:57658)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from ) id 1dpfGm-0002zu-82\n\tfor qemu-devel@nongnu.org; Wed, 06 Sep 2017 14:41:49 -0400","from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from ) id 1dpfGl-0001n7-CB\n\tfor qemu-devel@nongnu.org; Wed, 06 Sep 2017 14:41:48 -0400","from mx1.redhat.com ([209.132.183.28]:43862)\n\tby eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from ) id 1dpfGl-0001lJ-6J\n\tfor qemu-devel@nongnu.org; Wed, 06 Sep 2017 14:41:47 -0400","from smtp.corp.redhat.com\n\t(int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15])\n\t(using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby mx1.redhat.com (Postfix) with ESMTPS id 39DB88553D\n\tfor ; Wed, 6 Sep 2017 18:41:46 +0000 (UTC)","from dgilbert-t530.redhat.com (ovpn-117-207.ams2.redhat.com\n\t[10.36.117.207])\n\tby smtp.corp.redhat.com (Postfix) with ESMTP id 9BD0C5D6A0;\n\tWed, 6 Sep 2017 18:41:44 +0000 (UTC)"],"DMARC-Filter":"OpenDMARC Filter v1.3.2 mx1.redhat.com 39DB88553D","From":"\"Dr. David Alan Gilbert (git)\" ","To":"qemu-devel@nongnu.org","Date":"Wed, 6 Sep 2017 19:41:29 +0100","Message-Id":"<20170906184133.25524-5-dgilbert@redhat.com>","In-Reply-To":"<20170906184133.25524-1-dgilbert@redhat.com>","References":"<20170906184133.25524-1-dgilbert@redhat.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","X-Scanned-By":"MIMEDefang 2.79 on 10.5.11.15","X-Greylist":"Sender IP whitelisted, not delayed by milter-greylist-4.5.16\n\t(mx1.redhat.com [10.5.110.28]);\n\tWed, 06 Sep 2017 18:41:46 +0000 (UTC)","Content-Transfer-Encoding":"quoted-printable","X-detected-operating-system":"by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic]\n\t[fuzzy]","X-Received-From":"209.132.183.28","Subject":"[Qemu-devel] [PULL 4/8] host-utils: Simplify pow2ceil()","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"kwolf@redhat.com, armbru@redhat.com, peterx@redhat.com,\n\tquintela@redhat.com","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"},"content":"From: Markus Armbruster \n\nCc: Radim Krčmář \nSigned-off-by: Markus Armbruster \nMessage-Id: <1501148776-16890-4-git-send-email-armbru@redhat.com>\nReviewed-by: Eric Blake \nSigned-off-by: Dr. David Alan Gilbert \n---\n include/qemu/host-utils.h | 23 ++++++++++++++---------\n 1 file changed, 14 insertions(+), 9 deletions(-)","diff":"diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h\nindex 6c6005f5cf..5ac621cf1f 100644\n--- a/include/qemu/host-utils.h\n+++ b/include/qemu/host-utils.h\n@@ -381,18 +381,23 @@ static inline uint64_t pow2floor(uint64_t value)\n return 0x8000000000000000ull >> clz64(value);\n }\n \n-/* round up to the nearest power of 2 (0 if overflow) */\n+/*\n+ * Return @value rounded up to the nearest power of two modulo 2^64.\n+ * This is *zero* for @value > 2^63, so be careful.\n+ */\n static inline uint64_t pow2ceil(uint64_t value)\n {\n- uint8_t nlz = clz64(value);\n-\n- if (is_power_of_2(value)) {\n- return value;\n- }\n- if (!nlz) {\n- return 0;\n+ int n = clz64(value - 1);\n+\n+ if (!n) {\n+ /*\n+ * @value - 1 has no leading zeroes, thus @value - 1 >= 2^63\n+ * Therefore, either @value == 0 or @value > 2^63.\n+ * If it's 0, return 1, else return 0.\n+ */\n+ return !value;\n }\n- return 1ULL << (64 - nlz);\n+ return 0x8000000000000000ull >> (n - 1);\n }\n \n /**\n","prefixes":["PULL","4/8"]}