forked from osmocom/wireshark
47 lines
1.4 KiB
C
47 lines
1.4 KiB
C
/*
|
|
* bitz_ctz.h
|
|
*
|
|
* Wireshark - Network traffic analyzer
|
|
* By Gerald Combs <gerald@wireshark.org>
|
|
* Copyright 1998 Gerald Combs
|
|
*
|
|
* 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 Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
*/
|
|
|
|
#ifndef __WSUTIL_BITS_CTZ_H__
|
|
#define __WSUTIL_BITS_CTZ_H__
|
|
|
|
#include <glib.h>
|
|
|
|
static inline int
|
|
ws_ctz(guint32 x)
|
|
{
|
|
#if defined(__GNUC__) && ((__GNUC__ > 3) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
|
|
g_assert(x != 0);
|
|
|
|
return __builtin_ctz(x);
|
|
#else
|
|
/* From http://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightMultLookup */
|
|
static const int table[32] = {
|
|
0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
|
|
31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
|
|
};
|
|
|
|
return table[((guint32)((x & -(gint32)x) * 0x077CB531U)) >> 27];
|
|
#endif
|
|
}
|
|
|
|
#endif /* __WSUTIL_BITS_CTZ_H__ */
|