GNU bug report logs - #22689
25.1.50; implement logcount

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From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Mark Oteiza <mvoteiza <at> udel.edu>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 22689 <at> debbugs.gnu.org
Subject: bug#22689: [PATCH] Add logcount
Date: Sat, 30 Sep 2017 15:48:50 -0700

[Message part 1 (text/plain, inline)]

I looked at this patch after it landed in 'master'. Thanks for contributing it.

A couple of minor improvements. First, the implementation of logcount can use 
the count_one_bits functions already used by Emacs, rather than reinventing that 
wheel; these functions should be just as fast as __builtin_popcount etc. when 
using GCC. Second, logcount should count zero bits in negative numbers, for 
compatibility with Common Lisp. I installed the attached two patches to 
implement these improvements.

[0001-Simplify-logcount-implementation.patch (text/x-patch, attachment)]

[0002-Make-logcount-act-like-CL-on-negative-arg.patch (text/x-patch, attachment)]

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