From: | Anton Nikiforov <anton(at)nikiforov(dot)ru> |
---|---|
To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: int to inet conversion |
Date: | 2005-12-04 12:21:47 |
Message-ID: | 4392DF5B.7010204@nikiforov.ru |
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Lists: | pgsql-general |
Martijn van Oosterhout wrote:
> 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,
Sorry, did not quite catch.
t in this case is int, and there is no log2(int) function.....
Best regards,
Anton
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