On Thu, 2008-06-26 at 01:26 +0300, Tomas Winkler wrote: > On Wed, Jun 25, 2008 at 7:12 PM, Johannes Berg > <johannes@xxxxxxxxxxxxxxxx> wrote: > > On Wed, 2008-06-25 at 11:58 -0400, Pavel Roskin wrote: > > > >> > + unsigned long mid_range = (-1) / 2 + 1; > >> > >> What is that? I guess that's where Riemann's zeta function has its > >> non-trivial roots :-) > > > > > The Pavel hypothesis: "The Riemann hypothesis is correct when calculated > > in 32-bit integers" is obviously wrong ;) > > > Welcome to the Desert of the Real Welcome to C. mid_range is 1, as you can easily check. > >> > + time_diff = jiffies - bss->last_update > mid_range ? > >> > + jiffies - bss->last_update : > >> > + bss->last_update - jiffies; > >> > >> That's pretty hairy. Do we really lack a function to calculate time > >> difference? > > This is simplest as you can get under assumption that times are not > apart more then 1/2 of UL. > It would be overkill to translate it to timeval or anything we have > diff function for. Why would jiffies ever lag behind bss->last_update? When would (bss->last_update - jiffies) make sense? If it makes sense, how about indicating it somehow? It would be a value that decreases over time. > > Actually, come to think of it, isn't just doing the difference as in teh > > original patch correct in 32-bit unsigned integers? It'll wrap around a > > bit but that's ok, no? > > It would make a very recent beacon to be like half an hour old on > wraps, wouldn't it? No. Why would it? Can you give an example? If you are not increasing precision, wraparounds should make no difference. -- Regards, Pavel Roskin -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
