bits.c revision 1721fc956dfe30fd5dc5a49238c376ccbfdfd9d9 
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.  */
27unsigned
28bitcount(uint64_t u)
29{
30	int c = 0;
31	for (; u > 0; u &= u - 1)
32		c++;
33	return c;
34}
35