Fix a warning with MSVC

[stockfish] / src / bitboard.h

diff --git a/src/bitboard.h b/src/bitboard.h
index 77a824ba62106965ba9513803a19c650c092bb4c..a0f7ea8d69b0bfe325f4ceb060d0a91f49055210 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -61,16 +61,6 @@ const Bitboard Rank8BB = Rank1BB << (8 * 7);
 
 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];
@@ -225,6 +215,13 @@ template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_
 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;
@@ -242,6 +239,10 @@ inline unsigned magic_index(Square s, Bitboard occupied) {
 
 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)];
 }
 
@@ -257,6 +258,32 @@ inline Bitboard attacks_bb(Piece pc, Square s, Bitboard 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);
+
+#elif defined(_MSC_VER)
+
+  return (int)__popcnt64(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__)