From patchwork Thu Aug 27 19:33:01 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Vivier X-Patchwork-Id: 511406 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id CEE841401C7 for ; Fri, 28 Aug 2015 05:35:59 +1000 (AEST) Received: from localhost ([::1]:44322 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZV2xp-0002j9-Ua for incoming@patchwork.ozlabs.org; Thu, 27 Aug 2015 15:35:57 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39816) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZV2vF-0006em-Jf for qemu-devel@nongnu.org; Thu, 27 Aug 2015 15:33:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZV2vE-0007y9-QU for qemu-devel@nongnu.org; Thu, 27 Aug 2015 15:33:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53184) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZV2vE-0007xn-MM for qemu-devel@nongnu.org; Thu, 27 Aug 2015 15:33:16 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id 6D24C8E907 for ; Thu, 27 Aug 2015 19:33:16 +0000 (UTC) Received: from thinkpad.redhat.com (vpn1-7-222.ams2.redhat.com [10.36.7.222]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t7RJX7Zk024823; Thu, 27 Aug 2015 15:33:15 -0400 From: Laurent Vivier To: qemu-devel@nongnu.org, Stefan Hajnoczi , "Michael S . Tsirkin" , Paolo Bonzini Date: Thu, 27 Aug 2015 21:33:01 +0200 Message-Id: <1440703987-29012-4-git-send-email-lvivier@redhat.com> In-Reply-To: <1440703987-29012-1-git-send-email-lvivier@redhat.com> References: <1440703987-29012-1-git-send-email-lvivier@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v3 3/9] pcnet: remove muldiv64() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Originally, timers were ticks based, and it made sense to add ticks to current time to know when to trigger an alarm. But since commit: 7447545 change all other clock references to use nanosecond resolution accessors All timers use nanoseconds and we need to convert ticks to nanoseconds, by doing something like: y = muldiv64(x, get_ticks_per_sec(), PCI_FREQUENCY) where x is the number of device ticks and y the number of system ticks. y is used as nanoseconds in timer functions, it works because 1 tick is 1 nanosecond. (get_ticks_per_sec() is 10^9) But as PCI frequency is 33 MHz, we can also do: y = x * 30; /* 33 MHz PCI period is 30 ns */ Which is much more simple. This implies a 33.333333 MHz PCI frequency, but this is correct. Signed-off-by: Laurent Vivier Reviewed-by: Stefan Hajnoczi --- v3: part of "PCI: remove muldiv64()" hw/net/pcnet.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c index 3437376..0eb3cc4 100644 --- a/hw/net/pcnet.c +++ b/hw/net/pcnet.c @@ -670,8 +670,7 @@ static inline hwaddr pcnet_rdra_addr(PCNetState *s, int idx) static inline int64_t pcnet_get_next_poll_time(PCNetState *s, int64_t current_time) { int64_t next_time = current_time + - muldiv64(65536 - (CSR_SPND(s) ? 0 : CSR_POLL(s)), - get_ticks_per_sec(), 33000000L); + (65536 - (CSR_SPND(s) ? 0 : CSR_POLL(s))) * 30; if (next_time <= current_time) next_time = current_time + 1; return next_time;