2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
12 Stockfish 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
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
22 #if !defined(BITCOUNT_H_INCLUDED)
23 #define BITCOUNT_H_INCLUDED
35 /// count_1s() counts the number of nonzero bits in a bitboard.
36 /// We have different optimized versions according if platform
37 /// is 32 or 64 bits, and to the maximum number of nonzero bits.
38 /// We also support hardware popcnt instruction. See Readme.txt
39 /// on how to pgo compile with popcnt support.
40 template<BitCountType> inline int count_1s(Bitboard);
43 inline int count_1s<CNT64>(Bitboard b) {
44 b -= ((b>>1) & 0x5555555555555555ULL);
45 b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
46 b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
47 b *= 0x0101010101010101ULL;
52 inline int count_1s<CNT64_MAX15>(Bitboard b) {
53 b -= (b>>1) & 0x5555555555555555ULL;
54 b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
55 b *= 0x1111111111111111ULL;
60 inline int count_1s<CNT32>(Bitboard b) {
61 unsigned w = unsigned(b >> 32), v = unsigned(b);
62 v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
63 w -= (w >> 1) & 0x55555555;
64 v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
65 w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
66 v = ((v >> 4) + v) & 0x0F0F0F0F; // 0-8 in 8 bits
67 v += (((w >> 4) + w) & 0x0F0F0F0F); // 0-16 in 8 bits
68 v *= 0x01010101; // mul is fast on amd procs
73 inline int count_1s<CNT32_MAX15>(Bitboard b) {
74 unsigned w = unsigned(b >> 32), v = unsigned(b);
75 v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
76 w -= (w >> 1) & 0x55555555;
77 v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
78 w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
79 v += w; // 0-8 in 4 bits
85 inline int count_1s<CNT_POPCNT>(Bitboard b) {
86 #if !defined(USE_POPCNT)
87 return int(b != 0); // Avoid 'b not used' warning
88 #elif defined(_MSC_VER) && defined(__INTEL_COMPILER)
89 return _mm_popcnt_u64(b);
90 #elif defined(_MSC_VER)
92 #elif defined(__GNUC__)
94 __asm__("popcnt %1, %0" : "=r" (ret) : "r" (b));
100 /// cpu_has_popcnt() detects support for popcnt instruction at runtime
101 inline bool cpu_has_popcnt() {
103 int CPUInfo[4] = {-1};
104 __cpuid(CPUInfo, 0x00000001);
105 return (CPUInfo[2] >> 23) & 1;
109 /// CpuHasPOPCNT is a global constant initialized at startup that
110 /// is set to true if CPU on which application runs supports popcnt
111 /// hardware instruction. Unless USE_POPCNT is not defined.
112 #if defined(USE_POPCNT)
113 const bool CpuHasPOPCNT = cpu_has_popcnt();
115 const bool CpuHasPOPCNT = false;
119 /// CpuIs64Bit is a global constant initialized at compile time that
120 /// is set to true if CPU on which application runs is a 64 bits.
121 #if defined(IS_64BIT)
122 const bool CpuIs64Bit = true;
124 const bool CpuIs64Bit = false;
127 #endif // !defined(BITCOUNT_H_INCLUDED)