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SubjectRe: [PATCH] resizeable printk ring buffer


On Mon, 21 Aug 2000, Paul Gortmaker wrote:

> + i = 128;
> + while (i != len && i != 4) i>>=1;
> + if (i != len)
> + goto out;

just as an aside, there's a cute operation which tells you if there's
exactly 1 bit on in a word, which in this case would look like:

if (len & (len - 1))
goto out; /* not a power of 2 */

it's easiest to prove it with pencil and paper, and represent len in
binary form.

(there's a natural extension of this to counting 1-bits in a word...
which is a fun interview question i hear.)

-dean

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