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      1 /*
      2  * This file is part of ltrace.
      3  * Copyright (C) 2013 Petr Machata, Red Hat Inc.
      4  *
      5  * This program is free software; you can redistribute it and/or
      6  * modify it under the terms of the GNU General Public License as
      7  * published by the Free Software Foundation; either version 2 of the
      8  * License, or (at your option) any later version.
      9  *
     10  * This program is distributed in the hope that it will be useful, but
     11  * WITHOUT ANY WARRANTY; without even the implied warranty of
     12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13  * General Public License for more details.
     14  *
     15  * You should have received a copy of the GNU General Public License
     16  * along with this program; if not, write to the Free Software
     17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
     18  * 02110-1301 USA
     19  */
     20 
     21 #include "bits.h"
     22 
     23 /* This is called rarely, and any overhead will be lost in ptrace
     24  * noise, so the algorithm doesn't need to be terribly clever.  For
     25  * the same reason we don't bother defining the corresponding _32
     26  * variant.  */
     27 unsigned
     28 bitcount(uint64_t u)
     29 {
     30 	int c = 0;
     31 	for (; u > 0; u &= u - 1)
     32 		c++;
     33 	return c;
     34 }
     35