From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:32979) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUL5X-0004KC-I9 for qemu-devel@nongnu.org; Tue, 25 Aug 2015 16:45:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZUL5W-0000Gz-1I for qemu-devel@nongnu.org; Tue, 25 Aug 2015 16:44:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54520) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUL5V-0000Ge-SR for qemu-devel@nongnu.org; Tue, 25 Aug 2015 16:44:57 -0400 From: Laurent Vivier Date: Tue, 25 Aug 2015 22:44:46 +0200 Message-Id: <1440535491-4511-3-git-send-email-lvivier@redhat.com> In-Reply-To: <1440535491-4511-1-git-send-email-lvivier@redhat.com> References: <1440535491-4511-1-git-send-email-lvivier@redhat.com> Subject: [Qemu-devel] [PATCH 2/7] mips: remove muldiv64() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, Aurelien Jarno , Leon Alrae 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(), TIMER_FREQ) 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 MIPS timer frequency is 100 MHz, we can also do: y = x * 10; /* 100 MHz period is 10 ns */ Signed-off-by: Laurent Vivier --- hw/mips/cputimer.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff --git a/hw/mips/cputimer.c b/hw/mips/cputimer.c index 577c9ae..a74ae5c 100644 --- a/hw/mips/cputimer.c +++ b/hw/mips/cputimer.c @@ -25,7 +25,7 @@ #include "qemu/timer.h" #include "sysemu/kvm.h" -#define TIMER_FREQ 100 * 1000 * 1000 +#define TIMER_PERIOD 10 /* 10 ns period for 100 Mhz frequency */ /* XXX: do not use a global */ uint32_t cpu_mips_get_random (CPUMIPSState *env) @@ -49,9 +49,8 @@ static void cpu_mips_timer_update(CPUMIPSState *env) uint32_t wait; now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - wait = env->CP0_Compare - env->CP0_Count - - (uint32_t)muldiv64(now, TIMER_FREQ, get_ticks_per_sec()); - next = now + muldiv64(wait, get_ticks_per_sec(), TIMER_FREQ); + wait = env->CP0_Compare - env->CP0_Count - (uint32_t)(now / TIMER_PERIOD); + next = now + (uint64_t)wait * TIMER_PERIOD; timer_mod(env->timer, next); } @@ -79,8 +78,7 @@ uint32_t cpu_mips_get_count (CPUMIPSState *env) cpu_mips_timer_expire(env); } - return env->CP0_Count + - (uint32_t)muldiv64(now, TIMER_FREQ, get_ticks_per_sec()); + return env->CP0_Count + (uint32_t)(now / TIMER_PERIOD); } } @@ -95,9 +93,8 @@ void cpu_mips_store_count (CPUMIPSState *env, uint32_t count) env->CP0_Count = count; else { /* Store new count register */ - env->CP0_Count = - count - (uint32_t)muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), - TIMER_FREQ, get_ticks_per_sec()); + env->CP0_Count = count - + (uint32_t)(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) / TIMER_PERIOD); /* Update timer timer */ cpu_mips_timer_update(env); } @@ -121,8 +118,8 @@ void cpu_mips_start_count(CPUMIPSState *env) void cpu_mips_stop_count(CPUMIPSState *env) { /* Store the current value */ - env->CP0_Count += (uint32_t)muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), - TIMER_FREQ, get_ticks_per_sec()); + env->CP0_Count += (uint32_t)(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) / + TIMER_PERIOD); } static void mips_timer_cb (void *opaque) -- 2.1.0