Use opposite_color_squares() instead of same_color_squares()

[stockfish] / src / endgame.cpp

diff --git a/src/endgame.cpp b/src/endgame.cpp
index bb756f3b20cd558922c4fc6c416b055e962c3b6d..348feecf70bf5e170211460a23145a55749610dd 100644 (file)
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -155,7 +155,7 @@ Value EvaluationFunction<KBNK>::apply(const Position& pos) const {
   // kbnk_mate_table() tries to drive toward corners A1 or H8,
   // if we have a bishop that cannot reach the above squares we
   // mirror the kings so to drive enemy toward corners A8 or H1.
-  if (!same_color_squares(bishopSquare, SQ_A1))
+  if (opposite_color_squares(bishopSquare, SQ_A1))
   {
       winnerKSq = flop_square(winnerKSq);
       loserKSq = flop_square(loserKSq);
@@ -401,7 +401,7 @@ ScaleFactor ScalingFunction<KBPsK>::apply(const Position& pos) const {
       Square queeningSq = relative_square(strongerSide, make_square(pawnFile, RANK_8));
       Square kingSq = pos.king_square(weakerSide);
 
-      if (  !same_color_squares(queeningSq, bishopSq)
+      if (   opposite_color_squares(queeningSq, bishopSq)
           && file_distance(square_file(kingSq), pawnFile) <= 1)
       {
           // The bishop has the wrong color, and the defending king is on the
@@ -446,8 +446,8 @@ ScaleFactor ScalingFunction<KQKRPs>::apply(const Position& pos) const {
   Square kingSq = pos.king_square(weakerSide);
   if (   relative_rank(weakerSide, kingSq) <= RANK_2
       && relative_rank(weakerSide, pos.king_square(strongerSide)) >= RANK_4
-      && (pos.pieces(ROOK, weakerSide) & relative_rank_bb(weakerSide, RANK_3))
-      && (pos.pieces(PAWN, weakerSide) & relative_rank_bb(weakerSide, RANK_2))
+      && (pos.pieces(ROOK, weakerSide) & rank_bb(relative_rank(weakerSide, RANK_3)))
+      && (pos.pieces(PAWN, weakerSide) & rank_bb(relative_rank(weakerSide, RANK_2)))
       && (pos.attacks_from<KING>(kingSq) & pos.pieces(PAWN, weakerSide)))
   {
       Square rsq = pos.piece_list(weakerSide, ROOK, 0);
@@ -678,12 +678,12 @@ ScaleFactor ScalingFunction<KBPKB>::apply(const Position& pos) const {
   // Case 1: Defending king blocks the pawn, and cannot be driven away
   if (   square_file(weakerKingSq) == square_file(pawnSq)
       && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq)
-      && (  !same_color_squares(weakerKingSq, strongerBishopSq)
+      && (   opposite_color_squares(weakerKingSq, strongerBishopSq)
           || relative_rank(strongerSide, weakerKingSq) <= RANK_6))
       return SCALE_FACTOR_ZERO;
 
   // Case 2: Opposite colored bishops
-  if (!same_color_squares(strongerBishopSq, weakerBishopSq))
+  if (opposite_color_squares(strongerBishopSq, weakerBishopSq))
   {
       // We assume that the position is drawn in the following three situations:
       //
@@ -699,11 +699,12 @@ ScaleFactor ScalingFunction<KBPKB>::apply(const Position& pos) const {
           return SCALE_FACTOR_ZERO;
       else
       {
-          Bitboard ray = ray_bb(pawnSq, (strongerSide == WHITE)? SIGNED_DIR_N : SIGNED_DIR_S);
-          if (ray & pos.pieces(KING, weakerSide))
+          Bitboard path = squares_in_front_of(strongerSide, pawnSq);
+
+          if (path & pos.pieces(KING, weakerSide))
               return SCALE_FACTOR_ZERO;
 
-          if (  (pos.attacks_from<BISHOP>(weakerBishopSq) & ray)
+          if (  (pos.attacks_from<BISHOP>(weakerBishopSq) & path)
               && square_distance(weakerBishopSq, pawnSq) >= 3)
               return SCALE_FACTOR_ZERO;
       }
@@ -727,8 +728,7 @@ ScaleFactor ScalingFunction<KBPPKB>::apply(const Position& pos) const {
   Square wbsq = pos.piece_list(strongerSide, BISHOP, 0);
   Square bbsq = pos.piece_list(weakerSide, BISHOP, 0);
 
-  if (same_color_squares(wbsq, bbsq))
-      // Not opposite-colored bishops, no scaling
+  if (!opposite_color_squares(wbsq, bbsq))
       return SCALE_FACTOR_NONE;
 
   Square ksq = pos.king_square(weakerSide);
@@ -756,7 +756,7 @@ ScaleFactor ScalingFunction<KBPPKB>::apply(const Position& pos) const {
     // some square in the frontmost pawn's path.
     if (   square_file(ksq) == square_file(blockSq1)
         && relative_rank(strongerSide, ksq) >= relative_rank(strongerSide, blockSq1)
-        && !same_color_squares(ksq, wbsq))
+        && opposite_color_squares(ksq, wbsq))
         return SCALE_FACTOR_ZERO;
     else
         return SCALE_FACTOR_NONE;
@@ -766,14 +766,14 @@ ScaleFactor ScalingFunction<KBPPKB>::apply(const Position& pos) const {
     // in front of the frontmost pawn's path, and the square diagonally behind
     // this square on the file of the other pawn.
     if (   ksq == blockSq1
-        && !same_color_squares(ksq, wbsq)
+        && opposite_color_squares(ksq, wbsq)
         && (   bbsq == blockSq2
             || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(BISHOP, weakerSide))
             || rank_distance(r1, r2) >= 2))
         return SCALE_FACTOR_ZERO;
 
     else if (   ksq == blockSq2
-             && !same_color_squares(ksq, wbsq)
+             && opposite_color_squares(ksq, wbsq)
              && (   bbsq == blockSq1
                  || (pos.attacks_from<BISHOP>(blockSq1) & pos.pieces(BISHOP, weakerSide))))
         return SCALE_FACTOR_ZERO;
@@ -807,7 +807,7 @@ ScaleFactor ScalingFunction<KBPKN>::apply(const Position& pos) const {
 
   if (   square_file(weakerKingSq) == square_file(pawnSq)
       && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq)
-      && (  !same_color_squares(weakerKingSq, strongerBishopSq)
+      && (   opposite_color_squares(weakerKingSq, strongerBishopSq)
           || relative_rank(strongerSide, weakerKingSq) <= RANK_6))
       return SCALE_FACTOR_ZERO;