Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Wed, 21 Nov 2018 11:02:14 +0100 | Subject | Re: [RFC PATCH v2 09/14] m68k: hp300: Remove hp300_gettimeoffset() |
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Hi Finn,
On Wed, Nov 21, 2018 at 10:47 AM Finn Thain <fthain@telegraphics.com.au> wrote: > On Wed, 21 Nov 2018, Geert Uytterhoeven wrote: > > The 8520 CIA is almost identical to the 6526 CIA, as used in the C64... > > The 6526 CIA datasheet says, "In continuous mode, the timer will count > from the latched value to zero, generate and interrupt, reload the latched > value and repeat the procedure continuously."
I stand corrected...
> This suggests that either 0 or N (the latched value) would result from a > read from the counter immediately following an interrupt. Who can say > which? Just have to try it. The answer should allow us to avoid the risk > of a clocksource that jumps forwards and backwards.
The code in amiga_gettimeoffset() does:
ticks = hi << 8 | lo;
if (ticks > jiffy_ticks / 2) /* check for pending interrupt */ if (cia_set_irq(&ciab_base, 0) & CIA_ICR_TA) offset = 10000;
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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