/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2012 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
#if !defined(BITCOUNT_H_INCLUDED)
#define BITCOUNT_H_INCLUDED
+#include <cassert>
#include "types.h"
enum BitCountType {
- CNT64,
- CNT64_MAX15,
- CNT32,
- CNT32_MAX15,
- CNT_POPCNT
+ CNT_64,
+ CNT_64_MAX15,
+ CNT_32,
+ CNT_32_MAX15,
+ CNT_HW_POPCNT
};
-/// count_1s() counts the number of nonzero bits in a bitboard.
-/// We have different optimized versions according if platform
-/// is 32 or 64 bits, and to the maximum number of nonzero bits.
-/// We also support hardware popcnt instruction. See Readme.txt
-/// on how to pgo compile with popcnt support.
-template<BitCountType> inline int count_1s(Bitboard);
+/// Determine at compile time the best popcount<> specialization according if
+/// platform is 32 or 64 bits, to the maximum number of nonzero bits to count or
+/// use hardware popcnt instruction when 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 nonzero bits in a bitboard
+template<BitCountType> inline int popcount(Bitboard);
template<>
-inline int count_1s<CNT64>(Bitboard b) {
+inline int popcount<CNT_64>(Bitboard b) {
b -= ((b>>1) & 0x5555555555555555ULL);
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
}
template<>
-inline int count_1s<CNT64_MAX15>(Bitboard b) {
+inline int popcount<CNT_64_MAX15>(Bitboard b) {
b -= (b>>1) & 0x5555555555555555ULL;
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b *= 0x1111111111111111ULL;
}
template<>
-inline int count_1s<CNT32>(Bitboard b) {
+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;
}
template<>
-inline int count_1s<CNT32_MAX15>(Bitboard b) {
+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;
}
template<>
-inline int count_1s<CNT_POPCNT>(Bitboard b) {
+inline int popcount<CNT_HW_POPCNT>(Bitboard b) {
+
#if !defined(USE_POPCNT)
+
+ assert(false);
return int(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);
-#elif defined(__GNUC__)
+
+#else
+
unsigned long ret;
__asm__("popcnt %1, %0" : "=r" (ret) : "r" (b));
return ret;
+
#endif
}