GNU bug report logs - #22689
25.1.50; implement logcount

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From: Mark Oteiza <mvoteiza <at> udel.edu>
To: Benjamin Riefenstahl <b.riefenstahl <at> turtle-trading.net>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 22689 <at> debbugs.gnu.org
Subject: bug#22689: [PATCH] Add logcount
Date: Sat, 30 Sep 2017 12:59:04 -0400

On 30/09/17 at 06:50pm, Benjamin Riefenstahl wrote:
> Hi Mark,
> 
> Just a drive-by note:
> 
> Mark Oteiza writes:
> > +    {
> > +      unsigned int count;
> > +      for (count = 0; v; count++)
> > +        {
> > +          v &= v - 1;
> > +        }
> > +      XSETINT (res, v);
> > +    }
> 
> Isn't this a fancy way of just saying "XSETINT (res, 0)"?  The variable
> "count" is incremented but never used, so without it the loop
> degenerates to
> 
>       while (v)
>         {
>           v &= v - 1;
>         }
> 
> I other words, this just loops until "v == 0".
> 
> Maybe that assignment should be "XSETINT (res, count)"?  That would
> actually use the variable "count".

I think you're right, thank you.

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