extern int SquareDistance[SQUARE_NB][SQUARE_NB];
-extern Bitboard RookMasks [SQUARE_NB];
-extern Bitboard RookMagics [SQUARE_NB];
-extern Bitboard* RookAttacks[SQUARE_NB];
-extern unsigned RookShifts [SQUARE_NB];
-
-extern Bitboard BishopMasks [SQUARE_NB];
-extern Bitboard BishopMagics [SQUARE_NB];
-extern Bitboard* BishopAttacks[SQUARE_NB];
-extern unsigned BishopShifts [SQUARE_NB];
-
extern Bitboard SquareBB[SQUARE_NB];
extern Bitboard FileBB[FILE_NB];
extern Bitboard RankBB[RANK_NB];
template<PieceType Pt>
inline unsigned magic_index(Square s, Bitboard occupied) {
+ extern Bitboard RookMasks[SQUARE_NB];
+ extern Bitboard RookMagics[SQUARE_NB];
+ extern unsigned RookShifts[SQUARE_NB];
+ extern Bitboard BishopMasks[SQUARE_NB];
+ extern Bitboard BishopMagics[SQUARE_NB];
+ extern unsigned BishopShifts[SQUARE_NB];
+
Bitboard* const Masks = Pt == ROOK ? RookMasks : BishopMasks;
Bitboard* const Magics = Pt == ROOK ? RookMagics : BishopMagics;
unsigned* const Shifts = Pt == ROOK ? RookShifts : BishopShifts;
template<PieceType Pt>
inline Bitboard attacks_bb(Square s, Bitboard occupied) {
+
+ extern Bitboard* RookAttacks[SQUARE_NB];
+ extern Bitboard* BishopAttacks[SQUARE_NB];
+
return (Pt == ROOK ? RookAttacks : BishopAttacks)[s][magic_index<Pt>(s, occupied)];
}
}
+/// popcount() counts the number of non-zero bits in a bitboard
+
+inline int popcount(Bitboard b) {
+
+#ifndef USE_POPCNT
+
+ extern uint8_t PopCnt16[1 << 16];
+ union { Bitboard bb; uint16_t u[4]; } v = { b };
+ return PopCnt16[v.u[0]] + PopCnt16[v.u[1]] + PopCnt16[v.u[2]] + PopCnt16[v.u[3]];
+
+#elif defined(_MSC_VER) || defined(__INTEL_COMPILER)
+
+ return (int)_mm_popcnt_u64(b);
+
+#else // Assumed gcc or compatible compiler
+
+ return __builtin_popcountll(b);
+
+#endif
+}
+
+
/// lsb() and msb() return the least/most significant bit in a non-zero bitboard
#if defined(__GNUC__)