Re: int to inet conversion

From: Martijn van Oosterhout <kleptog(at)svana(dot)org>
To: Anton Nikiforov <anton(at)nikiforov(dot)ru>
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 14:23:19
Message-ID: 20051204142313.GA698@svana.org
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-general

On Sun, Dec 04, 2005 at 03:21:47PM +0300, Anton Nikiforov wrote:
> Martijn van Oosterhout wrote:
> >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.....

But there is a log(x,y) function, so log(2,t) would work also. Note
that 255.255.255.0 stored as integer is -256.

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)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.

In response to

Responses

Browse pgsql-general by date

  From Date Subject
Next Message Bruno Wolff III 2005-12-04 15:56:16 Re: Slow COUNT
Previous Message Tino Wildenhain 2005-12-04 13:40:49 Re: Slow COUNT