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https://github.com/HChaZZY/Stockfish.git
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85b08ce3ad
This time, do not break compatibility with some AMD machines that have SSE3 and popcnt, but do not have SSE4.2. No functional change.
105 lines
3.1 KiB
C++
105 lines
3.1 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
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Stockfish 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 3 of the License, or
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(at your option) any later version.
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Stockfish 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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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef BITCOUNT_H_INCLUDED
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#define BITCOUNT_H_INCLUDED
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#include <cassert>
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#include "types.h"
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enum BitCountType {
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CNT_64,
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CNT_64_MAX15,
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CNT_32,
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CNT_32_MAX15,
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CNT_HW_POPCNT
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};
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/// Determine at compile time the best popcount<> specialization according to
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/// whether the platform is 32 or 64 bit, the maximum number of non-zero
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/// bits to count and if the hardware popcnt instruction is available.
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const BitCountType Full = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64 : CNT_32;
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const BitCountType Max15 = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64_MAX15 : CNT_32_MAX15;
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/// popcount() counts the number of non-zero bits in a bitboard
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template<BitCountType> inline int popcount(Bitboard);
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template<>
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inline int popcount<CNT_64>(Bitboard b) {
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b -= (b >> 1) & 0x5555555555555555ULL;
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b = ((b >> 2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
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b = ((b >> 4) + b) & 0x0F0F0F0F0F0F0F0FULL;
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return (b * 0x0101010101010101ULL) >> 56;
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}
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template<>
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inline int popcount<CNT_64_MAX15>(Bitboard b) {
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b -= (b >> 1) & 0x5555555555555555ULL;
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b = ((b >> 2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
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return (b * 0x1111111111111111ULL) >> 60;
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}
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template<>
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inline int popcount<CNT_32>(Bitboard b) {
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unsigned w = unsigned(b >> 32), v = unsigned(b);
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v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
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w -= (w >> 1) & 0x55555555;
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v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
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w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
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v = ((v >> 4) + v + (w >> 4) + w) & 0x0F0F0F0F;
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return (v * 0x01010101) >> 24;
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}
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template<>
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inline int popcount<CNT_32_MAX15>(Bitboard b) {
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unsigned w = unsigned(b >> 32), v = unsigned(b);
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v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
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w -= (w >> 1) & 0x55555555;
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v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
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w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
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return ((v + w) * 0x11111111) >> 28;
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}
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template<>
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inline int popcount<CNT_HW_POPCNT>(Bitboard b) {
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#ifndef USE_POPCNT
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assert(false);
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return b != 0; // Avoid 'b not used' warning
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#elif defined(_MSC_VER) && defined(__INTEL_COMPILER)
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return _mm_popcnt_u64(b);
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#elif defined(_MSC_VER)
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return (int)__popcnt64(b);
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#else
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return __builtin_popcountll(b);
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#endif
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}
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#endif // #ifndef BITCOUNT_H_INCLUDED
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