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Groups > linux.kernel > #1293965
| From | Johannes Berg <johannes@sipsolutions.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 1/1] mac80211: improve the contiguous mask checking |
| Date | 2015-12-17 16:10 +0100 |
| Message-ID | <qGIlP-154-7@gated-at.bofh.it> (permalink) |
| References | <qGIlP-154-9@gated-at.bofh.it> <qGIlP-154-11@gated-at.bofh.it> <qGIlP-154-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, 2015-12-17 at 22:59 +0800, Zeng Zhaoxiu wrote:
> If the result of adding the first set bit to the mask is power of 2,
> the mask must be contiguous. "mask & -mask" can get the first set bit
> of mask gracefully.
> - if (__ffs64(mask) + hweight64(mask) != fls64(mask))
> {
> + inc = (mask & -mask);
> + val = mask + inc;
> + if ((val & (val - 1)) != 0) {
> /* not a contiguous mask ... not handled now! */
Hm. Ok, I can see how that would work, but it doesn't really seem like
much of an "improvement" to me? Surely I seem to need much more
thinking to understand this. There's no reason to optimise it either,
so why should we change it?
johannes
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Re: [PATCH 1/1] mac80211: improve the contiguous mask checking Johannes Berg <johannes@sipsolutions.net> - 2015-12-17 16:10 +0100
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