Remove BetweenBB Array #2076

[stockfish] / src / bitboard.h

diff --git a/src/bitboard.h b/src/bitboard.h
index af7b592ad564cb5a3af85ca97173d5259e390484..b1d961f4d9fc2b018a9084e66510004b7594a779 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -68,13 +68,12 @@ constexpr Bitboard Center      = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
 extern uint8_t PopCnt16[1 << 16];
 extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
 
-extern Bitboard SquareBB[SQUARE_NB];
-extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
 extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
 extern Bitboard DistanceRingBB[SQUARE_NB][8];
 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
 extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
 extern Bitboard KingFlank[FILE_NB];
+extern Bitboard SquareBB[SQUARE_NB];
 
 
 /// Magic holds all magic bitboards relevant data for a single square
@@ -102,34 +101,19 @@ struct Magic {
 extern Magic RookMagics[SQUARE_NB];
 extern Magic BishopMagics[SQUARE_NB];
 
-
-/// Overloads of bitwise operators between a Bitboard and a Square for testing
-/// whether a given bit is set in a bitboard, and for setting and clearing bits.
-
-inline Bitboard operator&(Bitboard b, Square s) {
+inline Bitboard square_bb(Square s) {
   assert(s >= SQ_A1 && s <= SQ_H8);
-  return b & SquareBB[s];
+  return SquareBB[s];
 }
 
-inline Bitboard operator|(Bitboard b, Square s) {
-  assert(s >= SQ_A1 && s <= SQ_H8);
-  return b | SquareBB[s];
-}
-
-inline Bitboard operator^(Bitboard b, Square s) {
-  assert(s >= SQ_A1 && s <= SQ_H8);
-  return b ^ SquareBB[s];
-}
-
-inline Bitboard& operator|=(Bitboard& b, Square s) {
-  assert(s >= SQ_A1 && s <= SQ_H8);
-  return b |= SquareBB[s];
-}
+/// Overloads of bitwise operators between a Bitboard and a Square for testing
+/// whether a given bit is set in a bitboard, and for setting and clearing bits.
 
-inline Bitboard& operator^=(Bitboard& b, Square s) {
-  assert(s >= SQ_A1 && s <= SQ_H8);
-  return b ^= SquareBB[s];
-}
+inline Bitboard  operator&( Bitboard  b, Square s) { return b &  square_bb(s); }
+inline Bitboard  operator|( Bitboard  b, Square s) { return b |  square_bb(s); }
+inline Bitboard  operator^( Bitboard  b, Square s) { return b ^  square_bb(s); }
+inline Bitboard& operator|=(Bitboard& b, Square s) { return b |= square_bb(s); }
+inline Bitboard& operator^=(Bitboard& b, Square s) { return b ^= square_bb(s); }
 
 constexpr bool more_than_one(Bitboard b) {
   return b & (b - 1);
@@ -200,13 +184,12 @@ inline Bitboard adjacent_files_bb(File f) {
 }
 
 
-/// between_bb() returns a bitboard representing all the squares between the two
-/// given ones. For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with
-/// the bits for square d5 and e6 set. If s1 and s2 are not on the same rank,
-/// file or diagonal, 0 is returned.
+/// between_bb() returns squares that are linearly between the given squares
+/// If the given squares are not on a same file/rank/diagonal, return 0.
 
 inline Bitboard between_bb(Square s1, Square s2) {
-  return BetweenBB[s1][s2];
+  return LineBB[s1][s2] & ( (AllSquares << (s1 +  (s1 < s2)))
+                           ^(AllSquares << (s2 + !(s1 < s2))));
 }
 
 
@@ -263,6 +246,9 @@ template<typename T1, typename T2> inline int distance(T2 x, T2 y);
 template<> inline int distance<File>(Square x, Square y) { return distance(file_of(x), file_of(y)); }
 template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_of(x), rank_of(y)); }
 
+template<class T> constexpr const T& clamp(const T& v, const T& lo, const T&  hi) {
+  return v < lo ? lo : v > hi ? hi : v;
+}
 
 /// attacks_bb() returns a bitboard representing all the squares attacked by a
 /// piece of type Pt (bishop or rook) placed on 's'.