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/*
* 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>
#if defined(__GNUC__) && ((__GNUC__ > 3) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
static inline int
ws_ctz(guint64 x)
{
return __builtin_ctzll(x);
}
#else
static inline int
__ws_ctz32(guint32 x)
{
/* 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];
}
static inline int
ws_ctz(guint64 x)
{
guint32 hi = x >> 32;
guint32 lo = (guint32) x;
if (lo == 0)
return 32 + __ws_ctz32(hi);
else
return __ws_ctz32(lo);
}
#endif
#endif /* __WSUTIL_BITS_CTZ_H__ */
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