1/* gtkpopcountprivate.h: Private implementation of popcount
2 *
3 * Copyright 2020 GNOME Foundation
4 *
5 * SPDX-License-Identifier: LGPL-2.1-or-later
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
19 */
20
21#pragma once
22
23#if (defined(_MSC_VER) && !_M_ARM && !_M_ARM64) && (__AVX__ || __SSE4_2__ || __POPCNT__)
24#include <intrin.h>
25
26static inline guint
27gtk_popcount (guint32 value)
28{
29 return __popcnt (value);
30}
31#elif defined(__GNUC__) || defined(__clang__)
32#define gtk_popcount(v) __builtin_popcount (v)
33#else
34static inline guint
35gtk_popcount (guint32 value)
36{
37 /* http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel */
38 return (((value & 0xfff) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f) +
39 ((((value & 0xfff000) >> 12) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f) +
40 (((value >> 24) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f);
41}
42#endif
43

source code of gtk/gtk/gtkpopcountprivate.h