From: Finn Thain <fthain@linux-m68k.org>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
Greg Kurz <groug@kaod.org>
Cc: qemu-ppc@nongnu.org, Laurent Vivier <laurent@vivier.eu>,
qemu-devel@nongnu.org
Subject: [PATCH v1 7/9] hw/mos6522: Avoid using discrepant QEMU clock values
Date: Fri, 24 Sep 2021 08:49:56 +1000 [thread overview]
Message-ID: <cf4fc15d3ecdbb1a22a855244348e7225503637a.1632437396.git.fthain@linux-m68k.org> (raw)
In-Reply-To: <cover.1632437396.git.fthain@linux-m68k.org>
mos6522_read() and mos6522_write() may call various functions to determine
timer irq state, timer counter value and QEMUTimer deadline. All called
functions must use the same value for the present time.
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
Changed since RFC
- Moved the changes to QEMUTimer callbacks to the next patch.
- Fix whitespace.
---
hw/misc/mos6522.c | 47 +++++++++++++++++++++++------------------------
1 file changed, 23 insertions(+), 24 deletions(-)
diff --git a/hw/misc/mos6522.c b/hw/misc/mos6522.c
index bfe1719b18..385ea81b62 100644
--- a/hw/misc/mos6522.c
+++ b/hw/misc/mos6522.c
@@ -39,9 +39,9 @@
/* XXX: implement all timer modes */
static void mos6522_timer1_update(MOS6522State *s, MOS6522Timer *ti,
- int64_t current_time);
+ int64_t now);
static void mos6522_timer2_update(MOS6522State *s, MOS6522Timer *ti,
- int64_t current_time);
+ int64_t now);
static void mos6522_update_irq(MOS6522State *s)
{
@@ -52,13 +52,12 @@ static void mos6522_update_irq(MOS6522State *s)
}
}
-static unsigned int get_counter(MOS6522State *s, MOS6522Timer *ti)
+static unsigned int get_counter(MOS6522State *s, MOS6522Timer *ti, int64_t now)
{
int64_t d;
unsigned int counter;
- d = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - ti->load_time,
- ti->frequency, NANOSECONDS_PER_SECOND);
+ d = muldiv64(now - ti->load_time, ti->frequency, NANOSECONDS_PER_SECOND);
if (ti->index == 0) {
/* the timer goes down from latch to -1 (period of latch + 2) */
@@ -88,7 +87,7 @@ static void set_counter(MOS6522State *s, MOS6522Timer *ti, unsigned int val)
}
static int64_t get_next_irq_time(MOS6522State *s, MOS6522Timer *ti,
- int64_t current_time)
+ int64_t now)
{
int64_t d, next_time;
unsigned int counter;
@@ -98,8 +97,7 @@ static int64_t get_next_irq_time(MOS6522State *s, MOS6522Timer *ti,
}
/* current counter value */
- d = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - ti->load_time,
- ti->frequency, NANOSECONDS_PER_SECOND);
+ d = muldiv64(now - ti->load_time, ti->frequency, NANOSECONDS_PER_SECOND);
/* the timer goes down from latch to -1 (period of latch + 2) */
if (d <= (ti->counter_value + 1)) {
@@ -122,20 +120,19 @@ static int64_t get_next_irq_time(MOS6522State *s, MOS6522Timer *ti,
trace_mos6522_get_next_irq_time(ti->latch, d, next_time - d);
next_time = muldiv64(next_time, NANOSECONDS_PER_SECOND, ti->frequency) +
ti->load_time;
-
- if (next_time <= current_time) {
- next_time = current_time + 1;
- }
return next_time;
}
static void mos6522_timer1_update(MOS6522State *s, MOS6522Timer *ti,
- int64_t current_time)
+ int64_t now)
{
if (!ti->timer) {
return;
}
- ti->next_irq_time = get_next_irq_time(s, ti, current_time);
+ ti->next_irq_time = get_next_irq_time(s, ti, now);
+ if (ti->next_irq_time <= now) {
+ ti->next_irq_time = now + 1;
+ }
if ((s->ier & T1_INT) == 0 || (s->acr & T1MODE) != T1MODE_CONT) {
timer_del(ti->timer);
} else {
@@ -144,12 +141,15 @@ static void mos6522_timer1_update(MOS6522State *s, MOS6522Timer *ti,
}
static void mos6522_timer2_update(MOS6522State *s, MOS6522Timer *ti,
- int64_t current_time)
+ int64_t now)
{
if (!ti->timer) {
return;
}
- ti->next_irq_time = get_next_irq_time(s, ti, current_time);
+ ti->next_irq_time = get_next_irq_time(s, ti, now);
+ if (ti->next_irq_time <= now) {
+ ti->next_irq_time = now + 1;
+ }
if ((s->ier & T2_INT) == 0) {
timer_del(ti->timer);
} else {
@@ -227,12 +227,12 @@ uint64_t mos6522_read(void *opaque, hwaddr addr, unsigned size)
val = s->dira;
break;
case VIA_REG_T1CL:
- val = get_counter(s, &s->timers[0]) & 0xff;
+ val = get_counter(s, &s->timers[0], now) & 0xff;
s->ifr &= ~T1_INT;
mos6522_update_irq(s);
break;
case VIA_REG_T1CH:
- val = get_counter(s, &s->timers[0]) >> 8;
+ val = get_counter(s, &s->timers[0], now) >> 8;
break;
case VIA_REG_T1LL:
val = s->timers[0].latch & 0xff;
@@ -241,12 +241,12 @@ uint64_t mos6522_read(void *opaque, hwaddr addr, unsigned size)
val = (s->timers[0].latch >> 8) & 0xff;
break;
case VIA_REG_T2CL:
- val = get_counter(s, &s->timers[1]) & 0xff;
+ val = get_counter(s, &s->timers[1], now) & 0xff;
s->ifr &= ~T2_INT;
mos6522_update_irq(s);
break;
case VIA_REG_T2CH:
- val = get_counter(s, &s->timers[1]) >> 8;
+ val = get_counter(s, &s->timers[1], now) >> 8;
break;
case VIA_REG_SR:
val = s->sr;
@@ -356,10 +356,9 @@ void mos6522_write(void *opaque, hwaddr addr, uint64_t val, unsigned size)
}
mos6522_update_irq(s);
/* if IER is modified starts needed timers */
- mos6522_timer1_update(s, &s->timers[0],
- qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
- mos6522_timer2_update(s, &s->timers[1],
- qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
+ now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ mos6522_timer1_update(s, &s->timers[0], now);
+ mos6522_timer2_update(s, &s->timers[1], now);
break;
default:
g_assert_not_reached();
--
2.26.3
next prev parent reply other threads:[~2021-09-24 0:10 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 22:49 [PATCH v1 0/9] hw/mos6522: VIA timer emulation fixes and improvements Finn Thain
2021-09-23 22:49 ` [PATCH v1 9/9] hw/mos6522: Implement oneshot mode Finn Thain
2021-09-23 22:49 ` [PATCH v1 1/9] hw/mos6522: Remove get_load_time() methods and functions Finn Thain
2021-09-23 22:49 ` [PATCH v1 8/9] hw/mos6522: Synchronize timer interrupt and timer counter Finn Thain
2021-09-23 22:49 ` Finn Thain [this message]
2021-09-23 22:49 ` [PATCH v1 4/9] hw/mos6522: Rename timer callback functions Finn Thain
2021-09-23 22:49 ` [PATCH v1 3/9] hw/mos6522: Remove redundant mos6522_timer1_update() calls Finn Thain
2021-09-23 22:49 ` [PATCH v1 6/9] hw/mos6522: Call mos6522_update_irq() when appropriate Finn Thain
2021-09-23 22:49 ` [PATCH v1 5/9] hw/mos6522: Fix initial timer counter reload Finn Thain
2021-09-23 22:49 ` [PATCH v1 2/9] hw/mos6522: Remove get_counter_value() methods and functions Finn Thain
2021-11-17 3:03 ` [PATCH v1 0/9] hw/mos6522: VIA timer emulation fixes and improvements Finn Thain
2021-11-18 11:13 ` Mark Cave-Ayland
2021-11-19 8:39 ` Finn Thain
2021-11-20 21:53 ` Mark Cave-Ayland
2021-11-20 23:38 ` Finn Thain
2021-11-22 17:00 ` Peter Maydell
2021-11-22 22:34 ` Finn Thain
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