Le 10/03/2021 à 14:10, Laurent Vivier a écrit : > Le 10/03/2021 à 13:56, Laurent Vivier a écrit : >> Le 10/03/2021 à 13:32, BALATON Zoltan a écrit : >>> On Wed, 10 Mar 2021, Mark Cave-Ayland wrote: >>>> The 60Hz timer is initialised using timer_new_ns() meaning that the timer >>>> interval should be measured in ns, and therefore its period is a thousand >>>> times too short. >>>> >>>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk> >>>> --- >>>> hw/misc/mac_via.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/hw/misc/mac_via.c b/hw/misc/mac_via.c >>>> index f994fefa7c..c6e1552a59 100644 >>>> --- a/hw/misc/mac_via.c >>>> +++ b/hw/misc/mac_via.c >>>> @@ -302,8 +302,8 @@ static void via1_sixty_hz_update(MOS6522Q800VIA1State >>>> *v1s) >>>> MOS6522State *s = MOS6522(v1s); >>>> >>>> /* 60 Hz irq */ >>>> - v1s->next_sixty_hz = (qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 16630) / >>>> - 16630 * 16630; >>>> + v1s->next_sixty_hz = (qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + >>>> 16630000) / >>>> + 16630000 * 16630000; >>> >>> Can you put this magic number in a #define maybe also rewriting it in a way >>> that shows it >>> corresponds to a 60 Hz interval. (There's NANOSECONDS_PER_SECOND defined in >>> include/qemu/timer.h >>> that could be used for that, there's also SCALE_MS that might replace 1000 >>> * 1000 elsewhere in this >>> file). Also NANOSECONDS_PER_SECOND / 60 is 16666666, should that value be >>> used here instead? >> >> In fact, the Mac Frequency is not exactly 60 Hz, in docs we can find 60.147 >> Hz, in kernel 60.15 Hz. >> I Think there are several ways to compute it... >> > > In fact, we can read: > > "the vertical retrace frequency is approximately 60.15 Hz, resulting in a > period of approximately > 16.63 milliseconds" > > https://developer.apple.com/library/archive/documentation/mac/pdf/Processes/Vertical_Retrace_Mgr.pdf
The exact value is 16625800 ns "Macintosh Family Hardware Reference" ISBN 0-201-19255-1 "The video interface" p. 13-3 "[...] This means the full frame is redisplayed every 370 scan lines, or once every 166625.8 µs." Thanks, Laurent
