From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39794) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZV2vE-0006eZ-Ng for qemu-devel@nongnu.org; Thu, 27 Aug 2015 15:33:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZV2vD-0007xL-BV for qemu-devel@nongnu.org; Thu, 27 Aug 2015 15:33:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53182) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZV2vD-0007xE-3L for qemu-devel@nongnu.org; Thu, 27 Aug 2015 15:33:15 -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 D130C8E907 for ; Thu, 27 Aug 2015 19:33:14 +0000 (UTC) From: Laurent Vivier Date: Thu, 27 Aug 2015 21:33:00 +0200 Message-Id: <1440703987-29012-3-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> Subject: [Qemu-devel] [PATCH v3 2/9] rtl8139: remove muldiv64() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, Stefan Hajnoczi , "Michael S . Tsirkin" , Paolo Bonzini 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 --- v3: part of "PCI: remove muldiv64()" hw/net/rtl8139.c | 14 ++++++-------- tests/rtl8139-test.c | 2 +- 2 files changed, 7 insertions(+), 9 deletions(-) diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c index edbb61c..1e119e6 100644 --- a/hw/net/rtl8139.c +++ b/hw/net/rtl8139.c @@ -63,7 +63,7 @@ /* debug RTL8139 card */ //#define DEBUG_RTL8139 1 -#define PCI_FREQUENCY 33000000L +#define PCI_PERIOD 30 /* 30 ns period = 33.333333 Mhz frequency */ #define SET_MASKED(input, mask, curr) \ ( ( (input) & ~(mask) ) | ( (curr) & (mask) ) ) @@ -2881,8 +2881,7 @@ static void rtl8139_io_writew(void *opaque, uint8_t addr, uint32_t val) static void rtl8139_set_next_tctr_time(RTL8139State *s) { - const uint64_t ns_per_period = - muldiv64(0x100000000LL, get_ticks_per_sec(), PCI_FREQUENCY); + const uint64_t ns_per_period = (uint64_t)PCI_PERIOD << 32; DPRINTF("entered rtl8139_set_next_tctr_time\n"); @@ -2900,7 +2899,7 @@ static void rtl8139_set_next_tctr_time(RTL8139State *s) if (!s->TimerInt) { timer_del(s->timer); } else { - uint64_t delta = muldiv64(s->TimerInt, get_ticks_per_sec(), PCI_FREQUENCY); + uint64_t delta = (uint64_t)s->TimerInt * PCI_PERIOD; if (s->TCTR_base + delta <= qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)) { delta += ns_per_period; } @@ -3174,8 +3173,8 @@ static uint32_t rtl8139_io_readl(void *opaque, uint8_t addr) break; case Timer: - ret = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - s->TCTR_base, - PCI_FREQUENCY, get_ticks_per_sec()); + ret = (qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - s->TCTR_base) / + PCI_PERIOD; DPRINTF("TCTR Timer read val=0x%08x\n", ret); break; @@ -3269,8 +3268,7 @@ static void rtl8139_pre_save(void *opaque) int64_t current_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); /* for migration to older versions */ - s->TCTR = muldiv64(current_time - s->TCTR_base, PCI_FREQUENCY, - get_ticks_per_sec()); + s->TCTR = (current_time - s->TCTR_base) / PCI_PERIOD; s->rtl8139_mmio_io_addr_dummy = 0; } diff --git a/tests/rtl8139-test.c b/tests/rtl8139-test.c index e749be3..ba62851 100644 --- a/tests/rtl8139-test.c +++ b/tests/rtl8139-test.c @@ -20,7 +20,7 @@ static void nop(void) { } -#define CLK 33000000 +#define CLK 33333333 static QPCIBus *pcibus; static QPCIDevice *dev; -- 2.1.0