43 lines
1.5 KiB
C
43 lines
1.5 KiB
C
/* gtkpopcountprivate.h: Private implementation of popcount
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*
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* Copyright 2020 GNOME Foundation
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*
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* SPDX-License-Identifier: LGPL-2.1-or-later
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#if (defined(_MSC_VER) && !_M_ARM && !_M_ARM64) && (__AVX__ || __SSE4_2__ || __POPCNT__)
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#include <intrin.h>
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static inline guint
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gtk_popcount (guint32 value)
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{
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return __popcnt (value);
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}
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#elif defined(__GNUC__) || defined(__clang__)
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#define gtk_popcount(v) __builtin_popcount (v)
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#else
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static inline guint
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gtk_popcount (guint32 value)
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{
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/* http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel */
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return (((value & 0xfff) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f) +
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((((value & 0xfff000) >> 12) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f) +
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(((value >> 24) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f);
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}
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#endif
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