mirror of
https://github.com/peterosterlund2/droidfish.git
synced 2024-11-28 14:33:54 +01:00
105 lines
3.1 KiB
C++
105 lines
3.1 KiB
C++
/*
|
|
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
|
|
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
|
|
Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
|
|
|
|
Stockfish is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
|
|
Stockfish 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 General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#ifndef BITCOUNT_H_INCLUDED
|
|
#define BITCOUNT_H_INCLUDED
|
|
|
|
#include <cassert>
|
|
#include "types.h"
|
|
|
|
enum BitCountType {
|
|
CNT_64,
|
|
CNT_64_MAX15,
|
|
CNT_32,
|
|
CNT_32_MAX15,
|
|
CNT_HW_POPCNT
|
|
};
|
|
|
|
/// Determine at compile time the best popcount<> specialization according to
|
|
/// whether the platform is 32 or 64 bit, the maximum number of non-zero
|
|
/// bits to count and if the hardware popcnt instruction is available.
|
|
const BitCountType Full = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64 : CNT_32;
|
|
const BitCountType Max15 = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64_MAX15 : CNT_32_MAX15;
|
|
|
|
|
|
/// popcount() counts the number of non-zero bits in a bitboard
|
|
template<BitCountType> inline int popcount(Bitboard);
|
|
|
|
template<>
|
|
inline int popcount<CNT_64>(Bitboard b) {
|
|
b -= (b >> 1) & 0x5555555555555555ULL;
|
|
b = ((b >> 2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
|
|
b = ((b >> 4) + b) & 0x0F0F0F0F0F0F0F0FULL;
|
|
return (b * 0x0101010101010101ULL) >> 56;
|
|
}
|
|
|
|
template<>
|
|
inline int popcount<CNT_64_MAX15>(Bitboard b) {
|
|
b -= (b >> 1) & 0x5555555555555555ULL;
|
|
b = ((b >> 2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
|
|
return (b * 0x1111111111111111ULL) >> 60;
|
|
}
|
|
|
|
template<>
|
|
inline int popcount<CNT_32>(Bitboard b) {
|
|
unsigned w = unsigned(b >> 32), v = unsigned(b);
|
|
v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
|
|
w -= (w >> 1) & 0x55555555;
|
|
v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
|
|
w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
|
|
v = ((v >> 4) + v + (w >> 4) + w) & 0x0F0F0F0F;
|
|
return (v * 0x01010101) >> 24;
|
|
}
|
|
|
|
template<>
|
|
inline int popcount<CNT_32_MAX15>(Bitboard b) {
|
|
unsigned w = unsigned(b >> 32), v = unsigned(b);
|
|
v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
|
|
w -= (w >> 1) & 0x55555555;
|
|
v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
|
|
w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
|
|
return ((v + w) * 0x11111111) >> 28;
|
|
}
|
|
|
|
template<>
|
|
inline int popcount<CNT_HW_POPCNT>(Bitboard b) {
|
|
|
|
#ifndef USE_POPCNT
|
|
|
|
assert(false);
|
|
return b != 0; // Avoid 'b not used' warning
|
|
|
|
#elif defined(_MSC_VER) && defined(__INTEL_COMPILER)
|
|
|
|
return _mm_popcnt_u64(b);
|
|
|
|
#elif defined(_MSC_VER)
|
|
|
|
return (int)__popcnt64(b);
|
|
|
|
#else
|
|
|
|
return __builtin_popcountll(b);
|
|
|
|
#endif
|
|
}
|
|
|
|
#endif // #ifndef BITCOUNT_H_INCLUDED
|