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1 office 1 /* popcount.c
2 *
3 * popcount() replacement function for systems that don't provide their own.
4 *
5 * Wireshark - Network traffic analyzer
6 * By Gerald Combs <gerald@wireshark.org>
7 * Copyright 1998 Gerald Combs
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version 2
12 * of the License, or (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22 */
23  
24 #include "config.h"
25  
26 #include "wsutil/popcount.h"
27  
28 int
29 popcount(unsigned int mask)
30 {
31 #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
32 /* GCC 3.4 or newer */
33 return __builtin_popcount(mask);
34 #else
35 /* HACKMEM 169 */
36 unsigned long y;
37  
38 y = (mask >> 1) &033333333333;
39 y = mask - y - ((y >>1) & 033333333333);
40 return (((y + (y >> 3)) & 030707070707) % 077);
41 #endif
42 }