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[Qemu-devel] [PULL 2/9] rtl8139: remove muldiv64()
From: |
Laurent Vivier |
Subject: |
[Qemu-devel] [PULL 2/9] rtl8139: remove muldiv64() |
Date: |
Fri, 25 Sep 2015 16:09:03 +0200 |
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 <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
---
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 b0d6c40..68e43f3 100644
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -64,7 +64,7 @@
/* 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) ) )
@@ -2834,8 +2834,7 @@ 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");
@@ -2853,7 +2852,7 @@ 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;
}
@@ -3127,8 +3126,8 @@ 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;
@@ -3222,8 +3221,7 @@ 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
- [Qemu-devel] [PULL 0/9] muldiv64 queue, Laurent Vivier, 2015/09/25
- [Qemu-devel] [PULL 2/9] rtl8139: remove muldiv64(),
Laurent Vivier <=
- [Qemu-devel] [PULL 4/9] mips: remove muldiv64(), Laurent Vivier, 2015/09/25
- [Qemu-devel] [PULL 1/9] i6300esb: remove muldiv64(), Laurent Vivier, 2015/09/25
- [Qemu-devel] [PULL 3/9] pcnet: remove muldiv64(), Laurent Vivier, 2015/09/25
- [Qemu-devel] [PULL 9/9] net: remove muldiv64(), Laurent Vivier, 2015/09/25
- [Qemu-devel] [PULL 8/9] bt: remove muldiv64(), Laurent Vivier, 2015/09/25
- [Qemu-devel] [PULL 7/9] hpet: remove muldiv64(), Laurent Vivier, 2015/09/25
- [Qemu-devel] [PULL 5/9] openrisc: remove muldiv64(), Laurent Vivier, 2015/09/25
- [Qemu-devel] [PULL 6/9] arm: clarify the use of muldiv64(), Laurent Vivier, 2015/09/25
- Re: [Qemu-devel] [PULL 0/9] muldiv64 queue, Peter Maydell, 2015/09/25