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 <fth...@linux-m68k.org> Reviewed-by: Philippe Mathieu-Daudé <f4...@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