Re: [PATCH] qemu: aspeed_timer: Use signed muldiv for timer resets

[Christian Svensson <blue@cmd.nu>]

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Ping. What's left to be done here?

On Tue, Nov 13, 2018 at 9:58 AM Christian Svensson <blue@cmd.nu> wrote:

>
>
> On Tue, Nov 13, 2018 at 1:27 AM Andrew Jeffery <andrew@aj.id.au> wrote:
> > By inspection the concept of the patch seems okay to me. However, the
> issue
> > that host-utils.h takes care of in addition to providing helpers is
> support for
> > those helpers on systems that don't support 128-bit integers. The patch
> should
> > be sent to the upstream lists, and I don't think we should be breaking
> > qemu-arm-* generally for systems that we might not care about.
>
> Ah, yes - I missed that there were two - one for systems with int128 and
> one for them
> without. Hm, that does complicate things.
>
> Given that we only have one operand that is ever negative, how do you feel
> about a patch
> that goes along the lines of:
>
> if (delta >= 0) {
>   t->start += muldiv64(delta, NANOSECONDS_PER_SECOND, rate);
> } else {
>    t->start = (int64_t)t->start - muldiv64(-delta, NANOSECONDS_PER_SECOND,
> rate);
> }
>
> That should avoid any issues I think, save us/me from implementing a
> signed muldiv,
> but cost a bit on the readable code side.
>
>

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