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bits.c
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bits.c
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/*
* This file is part of ltrace.
* Copyright (C) 2013 Petr Machata, Red Hat Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#include "bits.h"
/* This is called rarely, and any overhead will be lost in ptrace
* noise, so the algorithm doesn't need to be terribly clever. For
* the same reason we don't bother defining the corresponding _32
* variant. */
unsigned
bitcount(uint64_t u)
{
int c = 0;
for (; u > 0; u &= u - 1)
c++;
return c;
}