Re: int to inet conversion

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От Martijn van Oosterhout
Тема Re: int to inet conversion
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Msg-id 20051204115409.GC4883@svana.org
обсуждение исходный текст
Ответ на Re: int to inet conversion  (Anton Nikiforov <anton@nikiforov.ru>)
Ответы Re: int to inet conversion  (Anton Nikiforov <anton@nikiforov.ru>)
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On Sun, Dec 04, 2005 at 02:09:53PM +0300, Anton Nikiforov wrote:
> Sorry for my stupidity but, maybe there is a function that converts mask
> stored in int format to a numer of bits? ;)
> Your function easyly convert this mask to dot decimal notation, but how
> to count the number of 1 in it?

No, but you can write one the same way like so:

Let i be your input.
Calculate t = -i.
If i is in the right format, t will have exactly one bit set.
Test this with t <> 0 and (t & i) == t
If that's ok, then your answer is 32 - log2(t)

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.

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