62 lines
1.4 KiB
C
62 lines
1.4 KiB
C
/**
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* Furnace Tracker - multi-system chiptune tracker
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* Copyright (C) 2021-2023 tildearrow and contributors
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#if defined( _MSC_VER )
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#include <intrin.h>
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static inline int bsr(unsigned short v) {
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unsigned long idx;
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if (_BitScanReverse(&idx,(unsigned long)v)) {
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return idx;
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}
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else {
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return -1;
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}
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}
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#elif defined( __GNUC__ )
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static inline int bsr(unsigned short v)
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{
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if (v) {
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return 32 - __builtin_clz(v);
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}
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else{
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return -1;
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}
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}
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#else
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static inline int bsr(unsigned short v)
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{
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unsigned short mask = 0x8000;
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for (int i = 15; i >= 0; --i) {
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if (v&mask)
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return (int)i;
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mask>>=1;
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}
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return -1;
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}
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#endif
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