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/* gtkpopcountprivate.h: Private implementation of popcount
*
* Copyright 2020 GNOME Foundation
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#if defined(_MSC_VER)
#include <intrin.h>
static inline guint
gtk_popcount (guint32 value)
{
return __popcnt (value);
}
#elif defined(__GNUC__) || defined(__clang__)
# define gtk_popcount(v) __builtin_popcount(v)
#else
static inline guint
gtk_popcount (guint32 value)
{
/* http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel */
return (((value & 0xfff) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f) +
((((value & 0xfff000) >> 12) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f) +
(((value >> 24) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f);
}
#endif
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