4 * Wireshark - Network traffic analyzer
5 * By Gerald Combs <gerald@wireshark.org>
6 * Copyright 1998 Gerald Combs
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version 2
11 * of the License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
23 #ifndef __WSUTIL_BITS_CTZ_H__
24 #define __WSUTIL_BITS_CTZ_H__
28 #if defined(__GNUC__) && ((__GNUC__ > 3) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
32 return __builtin_ctzll(x);
38 /* From http://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightMultLookup */
39 static const int table[32] = {
40 0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
41 31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
44 return table[((guint32)((x & -(gint32)x) * 0x077CB531U)) >> 27];
51 guint32 lo = (guint32) x;
54 return 32 + __ws_ctz32(hi);
56 return __ws_ctz32(lo);
60 #endif /* __WSUTIL_BITS_CTZ_H__ */