Rewrite generate_pawn_moves() and simplify evasions

Big cleanup and semplification of pawns evasions that
now are pseudo-legal as the remaining moves. This
allow us to remove a lot of tricky code.

Verified against perft: no functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 0af95e2d34f0b5cc7320201a9afe1f456788bb87..18fb09439791e396b930f53bd0f0c2874ca6bd66 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -57,8 +57,7 @@ namespace {
   MoveStack* generate_castle_moves(const Position&, MoveStack*);
 
   template<Color Us, MoveType Type>
   MoveStack* generate_castle_moves(const Position&, MoveStack*);
 
   template<Color Us, MoveType Type>

-  MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard = EmptyBoardBB,
-                                 Square = SQ_NONE, Bitboard = EmptyBoardBB);
+  MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard, Square);

 
   // Template generate_piece_moves (captures and non-captures) with specializations and overloads
   template<PieceType>
 
   // Template generate_piece_moves (captures and non-captures) with specializations and overloads
   template<PieceType>


@@ -68,19 +67,19 @@ namespace {
   MoveStack* generate_piece_moves<KING>(const Position&, MoveStack*, Color, Bitboard);
 
   template<PieceType Piece, MoveType Type>
   MoveStack* generate_piece_moves<KING>(const Position&, MoveStack*, Color, Bitboard);
 
   template<PieceType Piece, MoveType Type>

-  inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us) {
+  inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us, Bitboard t) {

 
     assert(Piece == PAWN);
 
     assert(Piece == PAWN);

-    assert(Type == CAPTURE || Type == NON_CAPTURE);
+    assert(Type == CAPTURE || Type == NON_CAPTURE || Type == EVASION);

 
 

-    return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m)
-                        : generate_pawn_moves<BLACK, Type>(p, m));
+    return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m, t, SQ_NONE)
+                        : generate_pawn_moves<BLACK, Type>(p, m, t, SQ_NONE));

   }
 
   // Templates for non-capture checks generation
 
   template<PieceType Piece>
   }
 
   // Templates for non-capture checks generation
 
   template<PieceType Piece>

-  MoveStack* generate_discovered_checks(const Position& pos, Square from, MoveStack* mlist);
+  MoveStack* generate_discovered_checks(const Position& pos, MoveStack* mlist, Square from);

 
   template<PieceType>
   MoveStack* generate_direct_checks(const Position&, MoveStack*, Color, Bitboard, Square);
 
   template<PieceType>
   MoveStack* generate_direct_checks(const Position&, MoveStack*, Color, Bitboard, Square);


@@ -91,18 +90,6 @@ namespace {
     return (us == WHITE ? generate_pawn_moves<WHITE, CHECK>(p, m, dc, ksq)
                         : generate_pawn_moves<BLACK, CHECK>(p, m, dc, ksq));
   }
     return (us == WHITE ? generate_pawn_moves<WHITE, CHECK>(p, m, dc, ksq)
                         : generate_pawn_moves<BLACK, CHECK>(p, m, dc, ksq));
   }

-
-  // Template generate_piece_evasions with specializations
-  template<PieceType>
-  MoveStack* generate_piece_evasions(const Position&, MoveStack*, Color, Bitboard, Bitboard);
-
-  template<>
-  inline MoveStack* generate_piece_evasions<PAWN>(const Position& p, MoveStack* m,
-                                                  Color us, Bitboard t, Bitboard pnd) {
-
-    return (us == WHITE ? generate_pawn_moves<WHITE, EVASION>(p, m, pnd, SQ_NONE, t)
-                        : generate_pawn_moves<BLACK, EVASION>(p, m, pnd, SQ_NONE, t));
-  }

 }
 
 
 }
 
 


@@ -126,7 +113,7 @@ MoveStack* generate_captures(const Position& pos, MoveStack* mlist) {
   mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
   mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
   mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
   mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
   mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
   mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);

-  mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us);
+  mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us, target);

   return  generate_piece_moves<KING>(pos, mlist, us, target);
 }
 
   return  generate_piece_moves<KING>(pos, mlist, us, target);
 }
 


@@ -142,7 +129,7 @@ MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist) {
   Color us = pos.side_to_move();
   Bitboard target = pos.empty_squares();
 
   Color us = pos.side_to_move();
   Bitboard target = pos.empty_squares();
 

-  mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us);
+  mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us, target);

   mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
   mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
   mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
   mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
   mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
   mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);


@@ -153,7 +140,7 @@ MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist) {
 }
 
 
 }
 
 

-/// generate_non_capture_checks() generates all pseudo-legal non-captures and
+/// generate_non_capture_checks() generates all pseudo-legal non-captures and knight

 /// underpromotions that give check. Returns a pointer to the end of the move list.
 
 MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
 /// underpromotions that give check. Returns a pointer to the end of the move list.
 
 MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {


@@ -174,10 +161,10 @@ MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bi
      switch (pos.type_of_piece_on(from))
      {
       case PAWN:   /* Will be generated togheter with pawns direct checks */     break;
      switch (pos.type_of_piece_on(from))
      {
       case PAWN:   /* Will be generated togheter with pawns direct checks */     break;

-      case KNIGHT: mlist = generate_discovered_checks<KNIGHT>(pos, from, mlist); break;
-      case BISHOP: mlist = generate_discovered_checks<BISHOP>(pos, from, mlist); break;
-      case ROOK:   mlist = generate_discovered_checks<ROOK>(pos, from, mlist);   break;
-      case KING:   mlist = generate_discovered_checks<KING>(pos, from, mlist);   break;
+      case KNIGHT: mlist = generate_discovered_checks<KNIGHT>(pos, mlist, from); break;
+      case BISHOP: mlist = generate_discovered_checks<BISHOP>(pos, mlist, from); break;
+      case ROOK:   mlist = generate_discovered_checks<ROOK>(pos, mlist, from);   break;
+      case KING:   mlist = generate_discovered_checks<KING>(pos, mlist, from);   break;

       default: assert(false); break;
      }
   }
       default: assert(false); break;
      }
   }


@@ -194,16 +181,15 @@ MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bi
 /// generate_evasions() generates all pseudo-legal check evasions when
 /// the side to move is in check. Returns a pointer to the end of the move list.
 
 /// generate_evasions() generates all pseudo-legal check evasions when
 /// the side to move is in check. Returns a pointer to the end of the move list.
 

-MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
+MoveStack* generate_evasions(const Position& pos, MoveStack* mlist) {

 
   assert(pos.is_ok());
   assert(pos.is_check());
 
   Bitboard b;
 
   assert(pos.is_ok());
   assert(pos.is_check());
 
   Bitboard b;

-  Square from, to, checksq;
+  Square from, checksq;

   int checkersCnt = 0;
   Color us = pos.side_to_move();
   int checkersCnt = 0;
   Color us = pos.side_to_move();

-  Color them = opposite_color(us);

   Square ksq = pos.king_square(us);
   Bitboard checkers = pos.checkers();
   Bitboard sliderAttacks = EmptyBoardBB;
   Square ksq = pos.king_square(us);
   Bitboard checkers = pos.checkers();
   Bitboard sliderAttacks = EmptyBoardBB;


@@ -220,7 +206,7 @@ MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pin
       checkersCnt++;
       checksq = pop_1st_bit(&b);
 
       checkersCnt++;
       checksq = pop_1st_bit(&b);
 

-      assert(pos.color_of_piece_on(checksq) == them);
+      assert(pos.color_of_piece_on(checksq) == opposite_color(us));

 
       switch (pos.type_of_piece_on(checksq))
       {
 
       switch (pos.type_of_piece_on(checksq))
       {


@@ -247,62 +233,15 @@ MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pin
   if (checkersCnt > 1)
       return mlist;
 
   if (checkersCnt > 1)
       return mlist;
 

-  Bitboard target = squares_between(checksq, ksq);
-
-  // Pawn captures
-  b = pos.attacks_from<PAWN>(checksq, them) & pos.pieces(PAWN, us) & ~pinned;
-  while (b)
-  {
-      from = pop_1st_bit(&b);
-      if (relative_rank(us, checksq) == RANK_8)
-      {
-          (*mlist++).move = make_promotion_move(from, checksq, QUEEN);
-          (*mlist++).move = make_promotion_move(from, checksq, ROOK);
-          (*mlist++).move = make_promotion_move(from, checksq, BISHOP);
-          (*mlist++).move = make_promotion_move(from, checksq, KNIGHT);
-      } else
-          (*mlist++).move = make_move(from, checksq);
-  }
-
-  // Pawn blocking evasions (possible only if the checking piece is a slider)
-  if (sliderAttacks)
-      mlist = generate_piece_evasions<PAWN>(pos, mlist, us, target, pinned);
-
-  // Add the checking piece to the target squares
-  target |= checkers;
+  // Find squares where a blocking evasion or a capture of the
+  // checker piece is possible.
+  Bitboard target = squares_between(checksq, ksq) | checkers;

 
 

-  // Captures and blocking evasions for the other pieces
+  mlist = generate_piece_moves<PAWN, EVASION>(pos, mlist, us, target);

   mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
   mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
   mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
   mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
   mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
   mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);

-  mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
-
-  // Finally, the special case of en passant captures. An en passant
-  // capture can only be a check evasion if the check is not a discovered
-  // check. If pos.ep_square() is set, the last move made must have been
-  // a double pawn push. If, furthermore, the checking piece is a pawn,
-  // an en passant check evasion may be possible.
-  if (pos.ep_square() != SQ_NONE && (checkers & pos.pieces(PAWN, them)))
-  {
-      to = pos.ep_square();
-      b = pos.attacks_from<PAWN>(to, them) & pos.pieces(PAWN, us);
-
-      // The checking pawn cannot be a discovered (bishop) check candidate
-      // otherwise we were in check also before last double push move.
-      assert(!bit_is_set(pos.discovered_check_candidates(them), checksq));
-      assert(count_1s(b) == 1 || count_1s(b) == 2);
-
-      b &= ~pinned;
-      while (b)
-      {
-          from = pop_1st_bit(&b);
-          // Move is always legal because checking pawn is not a discovered
-          // check candidate and our capturing pawn has been already tested
-          // against pinned pieces.
-          (*mlist++).move = make_ep_move(from, to);
-      }
-  }
-  return mlist;
+  return  generate_piece_moves<QUEEN>(pos, mlist, us, target);

 }
 
 
 }
 
 


@@ -319,7 +258,7 @@ MoveStack* generate_moves(const Position& pos, MoveStack* mlist, bool pseudoLega
 
   // Generate pseudo-legal moves
   if (pos.is_check())
 
   // Generate pseudo-legal moves
   if (pos.is_check())

-      last = generate_evasions(pos, mlist, pinned);
+      last = generate_evasions(pos, mlist);

   else {
       last = generate_captures(pos, mlist);
       last = generate_noncaptures(pos, last);
   else {
       last = generate_captures(pos, mlist);
       last = generate_noncaptures(pos, last);


@@ -348,7 +287,7 @@ bool move_is_legal(const Position& pos, const Move m) {
   MoveStack* last = generate_moves(pos, mlist, true);
   for (MoveStack* cur = mlist; cur != last; cur++)
       if (cur->move == m)
   MoveStack* last = generate_moves(pos, mlist, true);
   for (MoveStack* cur = mlist; cur != last; cur++)
       if (cur->move == m)

-          return pos.pl_move_is_legal(m);
+          return pos.pl_move_is_legal(m, pos.pinned_pieces(pos.side_to_move()));

 
   return false;
 }
 
   return false;
 }


@@ -481,24 +420,6 @@ namespace {
     return mlist;
   }
 
     return mlist;
   }
 

-  template<PieceType Piece>
-  MoveStack* generate_piece_evasions(const Position& pos, MoveStack* mlist,
-                                     Color us, Bitboard target, Bitboard pinned) {
-    Square from;
-    Bitboard b;
-    const Square* ptr = pos.piece_list_begin(us, Piece);
-
-    while ((from = *ptr++) != SQ_NONE)
-    {
-        if (pinned && bit_is_set(pinned, from))
-            continue;
-
-        b = pos.attacks_from<Piece>(from) & target;
-        SERIALIZE_MOVES(b);
-    }
-    return mlist;
-  }
-

   template<Color Us, SquareDelta Direction>
   inline Bitboard move_pawns(Bitboard p) {
 
   template<Color Us, SquareDelta Direction>
   inline Bitboard move_pawns(Bitboard p) {
 


@@ -512,8 +433,8 @@ namespace {
         return p;
   }
 
         return p;
   }
 

-  template<Color Us, SquareDelta Diagonal>
-  MoveStack* generate_pawn_diagonal_captures(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion) {
+  template<Color Us, MoveType Type, SquareDelta Diagonal>
+  inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool possiblePromotion) {

 
     // Calculate our parametrized parameters at compile time
     const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
 
     // Calculate our parametrized parameters at compile time
     const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);


@@ -527,131 +448,147 @@ namespace {
     // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
     Bitboard b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
 
     // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
     Bitboard b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
 

-    // Capturing promotions
-    if (promotion)
+    // Capturing promotions and under-promotions
+    if (possiblePromotion)

     {
         Bitboard b2 = b1 & TRank8BB;
         b1 &= ~TRank8BB;
         while (b2)
         {
             to = pop_1st_bit(&b2);
     {
         Bitboard b2 = b1 & TRank8BB;
         b1 &= ~TRank8BB;
         while (b2)
         {
             to = pop_1st_bit(&b2);

-            (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
+
+            if (Type == CAPTURE || Type == EVASION)
+                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
+
+            if (Type == NON_CAPTURE || Type == EVASION)
+            {
+                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, ROOK);
+                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, BISHOP);
+                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, KNIGHT);
+            }
+
+            // This is the only possible under promotion that can give a check
+            // not already included in the queen-promotion. It is not sure that
+            // the promoted knight will give check, but it doesn't worth to verify.
+            if (Type == CHECK)
+                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, KNIGHT);

         }
     }
 
         }
     }
 

-    // Capturing non-promotions
-    SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
+    // Serialize standard captures
+    if (Type == CAPTURE || Type == EVASION)
+        SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
+

     return mlist;
   }
 
   template<Color Us, MoveType Type>
     return mlist;
   }
 
   template<Color Us, MoveType Type>

-  MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard dcp,
-                                 Square ksq, Bitboard blockSquares) {
+  MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {

 
     // Calculate our parametrized parameters at compile time
     const Color Them = (Us == WHITE ? BLACK : WHITE);
     const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
     const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
     const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
 
     // Calculate our parametrized parameters at compile time
     const Color Them = (Us == WHITE ? BLACK : WHITE);
     const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
     const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
     const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);

-    const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
-    const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);

     const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
 
     const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
 

-    Bitboard b1, b2, dcPawns1, dcPawns2;

     Square to;
     Square to;

-    Bitboard pawns = (Type == EVASION ? pos.pieces(PAWN, Us) & ~dcp : pos.pieces(PAWN, Us));
+    Bitboard b1, b2, enemyPieces, emptySquares;
+    Bitboard pawns = pos.pieces(PAWN, Us);

     bool possiblePromotion = pawns & TRank7BB;
 
     bool possiblePromotion = pawns & TRank7BB;
 

-    if (Type == CAPTURE)
+    // Standard captures and capturing promotions and underpromotions
+    if (Type == CAPTURE || Type == EVASION || possiblePromotion)

     {
     {

-        // Standard captures and capturing promotions in both directions
-        Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
-        mlist = generate_pawn_diagonal_captures<Us, DELTA_NE>(mlist, pawns, enemyPieces, possiblePromotion);
-        mlist = generate_pawn_diagonal_captures<Us, DELTA_NW>(mlist, pawns, enemyPieces, possiblePromotion);
+        enemyPieces = (Type == CAPTURE ? target : pos.pieces_of_color(opposite_color(Us)));
+
+        if (Type == EVASION)
+            enemyPieces &= target; // Capture only the checker piece
+
+        mlist = generate_pawn_captures<Us, Type, DELTA_NE>(mlist, pawns, enemyPieces, possiblePromotion);
+        mlist = generate_pawn_captures<Us, Type, DELTA_NW>(mlist, pawns, enemyPieces, possiblePromotion);

     }
 
     }
 

+    // Non-capturing promotions and underpromotions

     if (possiblePromotion)
     {
     if (possiblePromotion)
     {

-        // When generating checks consider under-promotion moves (both captures
-        // and non captures) only if can give a discovery check. Note that dcp
-        // is dc bitboard or pinned bitboard when Type == EVASION.
-        Bitboard pp = (Type == CHECK ? pawns & dcp : pawns);
+        b1 = move_pawns<Us, DELTA_N>(pawns) & TRank8BB & pos.empty_squares();

 
 

-        if (Type != EVASION && Type != CAPTURE)
-        {
-            Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
-
-            // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
-            b1 = move_pawns<Us, DELTA_NE>(pp) & ~FileABB & enemyPieces & TRank8BB;
-            while (b1)
-            {
-                to = pop_1st_bit(&b1);
-                (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, ROOK);
-                (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, BISHOP);
-                (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, KNIGHT);
-            }
-
-            // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
-            b1 = move_pawns<Us, DELTA_NW>(pp) & ~FileHBB & enemyPieces & TRank8BB;
-            while (b1)
-            {
-                to = pop_1st_bit(&b1);
-                (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, ROOK);
-                (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, BISHOP);
-                (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, KNIGHT);
-            }
-        }
-
-        // Underpromotion pawn pushes. Also queen promotions for evasions and captures.
-        b1 = move_pawns<Us, DELTA_N>(pp) & TRank8BB;
-        b1 &= (Type == EVASION ? blockSquares : pos.empty_squares());
+        if (Type == EVASION)
+            b1 &= target; // Only blocking promotion pushes

 
         while (b1)
         {
             to = pop_1st_bit(&b1);
 
         while (b1)
         {
             to = pop_1st_bit(&b1);

-            if (Type == EVASION || Type == CAPTURE)
+
+            if (Type == CAPTURE || Type == EVASION)

                 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
 
                 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
 

-            if (Type != CAPTURE)
+            if (Type == NON_CAPTURE || Type == EVASION)

             {
                 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
                 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
                 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
             }
             {
                 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
                 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
                 (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
             }

+
+            // This is the only possible under promotion that can give a check
+            // not already included in the queen-promotion.
+            if (Type == CHECK && bit_is_set(pos.attacks_from<KNIGHT>(to), pos.king_square(Them)))
+                (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);

         }
     }
 
         }
     }
 

+    // Standard pawn pushes and double pushes

     if (Type != CAPTURE)
     {
     if (Type != CAPTURE)
     {

-        Bitboard emptySquares = pos.empty_squares();
-        dcPawns1 = dcPawns2 = EmptyBoardBB;
-        if (Type == CHECK && (pawns & dcp))
+        emptySquares = (Type == NON_CAPTURE ? target : pos.empty_squares());
+
+        // Single and double pawn pushes
+        b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
+        b2 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
+
+        // Filter out unwanted pushes according to the move type
+        if (Type == EVASION)

         {
         {

-            // Pawn moves which gives discovered check. This is possible only if the
-            // pawn is not on the same file as the enemy king, because we don't
-            // generate captures.
-            dcPawns1 = move_pawns<Us, DELTA_N>(pawns & dcp & ~file_bb(ksq)) & emptySquares & ~TRank8BB;
-            dcPawns2 = move_pawns<Us, DELTA_N>(dcPawns1 & TRank3BB) & emptySquares;
+            b1 &= target;
+            b2 &= target;

         }
         }

+        else if (Type == CHECK)
+        {
+            // Pawn moves which give direct cheks
+            b1 &= pos.attacks_from<PAWN>(ksq, Them);
+            b2 &= pos.attacks_from<PAWN>(ksq, Them);
+
+            // Pawn moves which gives discovered check. This is possible only if
+            // the pawn is not on the same file as the enemy king, because we
+            //  don't generate captures.
+            if (pawns & target) // For CHECK type target is dc bitboard
+            {
+                Bitboard dc1 = move_pawns<Us, DELTA_N>(pawns & target & ~file_bb(ksq)) & emptySquares & ~TRank8BB;
+                Bitboard dc2 = move_pawns<Us, DELTA_N>(dc1 & TRank3BB) & emptySquares;

 
 

-        // Single pawn pushes
-        b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
-        b2 = (Type == CHECK ? (b1 & pos.attacks_from<PAWN>(ksq, Them)) | dcPawns1 :
-             (Type == EVASION ? b1 & blockSquares : b1));
-        SERIALIZE_MOVES_D(b2, -TDELTA_N);
-
-        // Double pawn pushes
-        b1 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
-        b2 = (Type == CHECK ? (b1 & pos.attacks_from<PAWN>(ksq, Them)) | dcPawns2 :
-             (Type == EVASION ? b1 & blockSquares : b1));
+                b1 |= dc1;
+                b2 |= dc2;
+            }
+        }
+        SERIALIZE_MOVES_D(b1, -TDELTA_N);

         SERIALIZE_MOVES_D(b2, -TDELTA_N -TDELTA_N);
     }
         SERIALIZE_MOVES_D(b2, -TDELTA_N -TDELTA_N);
     }

-    else if (pos.ep_square() != SQ_NONE) // En passant captures
+
+    // En passant captures
+    if ((Type == CAPTURE || Type == EVASION) && pos.ep_square() != SQ_NONE)

     {
         assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6);
         assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3);
 
     {
         assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6);
         assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3);
 

+        // An en passant capture can be an evasion only if the checking piece
+        // is the double pushed pawn and so is in the target. Otherwise this
+        // is a discovery check and we are forced to do otherwise.
+        if (Type == EVASION && !bit_is_set(target, pos.ep_square() - TDELTA_N))
+            return mlist;
+

         b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);
         b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);

+

         assert(b1 != EmptyBoardBB);
 
         while (b1)
         assert(b1 != EmptyBoardBB);
 
         while (b1)


@@ -664,7 +601,7 @@ namespace {
   }
 
   template<PieceType Piece>
   }
 
   template<PieceType Piece>

-  MoveStack* generate_discovered_checks(const Position& pos, Square from, MoveStack* mlist) {
+  MoveStack* generate_discovered_checks(const Position& pos, MoveStack* mlist, Square from) {

 
     assert(Piece != QUEEN);
 
 
     assert(Piece != QUEEN);
 

diff --git a/src/movegen.h b/src/movegen.h
index fdc90139850c8db8ec360da408ac8312846d46a5..7d2efec37883bafd5ec457a8232cfa80ce05e086 100644 (file)
--- a/src/movegen.h
+++ b/src/movegen.h
@@ -35,7 +35,7 @@
 extern MoveStack* generate_captures(const Position& pos, MoveStack* mlist);
 extern MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist);
 extern MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc);
 extern MoveStack* generate_captures(const Position& pos, MoveStack* mlist);
 extern MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist);
 extern MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc);

-extern MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned);
+extern MoveStack* generate_evasions(const Position& pos, MoveStack* mlist);

 extern MoveStack* generate_moves(const Position& pos, MoveStack* mlist, bool pseudoLegal = false);
 extern bool move_is_legal(const Position& pos, const Move m, Bitboard pinned);
 extern bool move_is_legal(const Position& pos, const Move m);
 extern MoveStack* generate_moves(const Position& pos, MoveStack* mlist, bool pseudoLegal = false);
 extern bool move_is_legal(const Position& pos, const Move m, Bitboard pinned);
 extern bool move_is_legal(const Position& pos, const Move m);

diff --git a/src/movepick.cpp b/src/movepick.cpp
index a2ea3a7354f951dcb9edce6007118874db36e832..a562662e359e514d878b17879dcd18395d940553 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -144,7 +144,7 @@ void MovePicker::go_next_phase() {
 
   case PH_EVASIONS:
       assert(pos.is_check());
 
   case PH_EVASIONS:
       assert(pos.is_check());

-      lastMove = generate_evasions(pos, moves, pinned);
+      lastMove = generate_evasions(pos, moves);

       score_evasions();
       return;
 
       score_evasions();
       return;
 

diff --git a/src/position.cpp b/src/position.cpp
index be4e234d99d9b937036ee9d6fabb9cec170a0e40..306cebfc75f0947f55f8bcc5bef18392a90b87da 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -458,13 +458,6 @@ void Position::find_checkers() {
 
 /// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
 
 
 /// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
 

-bool Position::pl_move_is_legal(Move m) const {
-
-  // If we're in check, all pseudo-legal moves are legal, because our
-  // check evasion generator only generates true legal moves.
-  return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move()));
-}
-

 bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
 
   assert(is_ok());
 bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
 
   assert(is_ok());


@@ -1337,7 +1330,6 @@ int Position::see(Square from, Square to) const {
 
   Bitboard attackers, stmAttackers, b;
 
 
   Bitboard attackers, stmAttackers, b;
 

-  assert(!shortcut || from != SQ_NONE);

   assert(square_is_ok(from) || from == SQ_NONE);
   assert(square_is_ok(to));
 
   assert(square_is_ok(from) || from == SQ_NONE);
   assert(square_is_ok(to));
 

diff --git a/src/position.h b/src/position.h
index f2f517e219445a601f4d90690572cb1a40e1b288..2568563cb5d335147d700e509a6349ea14f250df 100644 (file)
--- a/src/position.h
+++ b/src/position.h
@@ -202,7 +202,6 @@ public:
   template<PieceType> Bitboard attacks_from(Square s, Color c) const;
 
   // Properties of moves
   template<PieceType> Bitboard attacks_from(Square s, Color c) const;
 
   // Properties of moves

-  bool pl_move_is_legal(Move m) const;

   bool pl_move_is_legal(Move m, Bitboard pinned) const;
   bool move_is_check(Move m) const;
   bool move_is_check(Move m, Bitboard dcCandidates) const;
   bool pl_move_is_legal(Move m, Bitboard pinned) const;
   bool move_is_check(Move m) const;
   bool move_is_check(Move m, Bitboard dcCandidates) const;

diff --git a/src/san.cpp b/src/san.cpp
index 0e9b531003cb9c69595b84ee6540aec4d0689532..f155887809f6cccca81d672de3c52f674ba6fa50 100644 (file)
--- a/src/san.cpp
+++ b/src/san.cpp
@@ -142,13 +142,14 @@ Move move_from_san(const Position& pos, const string& movestr) {
   assert(pos.is_ok());
 
   MovePicker mp = MovePicker(pos, MOVE_NONE, OnePly, H);
   assert(pos.is_ok());
 
   MovePicker mp = MovePicker(pos, MOVE_NONE, OnePly, H);

+  Bitboard pinned = pos.pinned_pieces(pos.side_to_move());

 
   // Castling moves
   if (movestr == "O-O-O" || movestr == "O-O-O+")
   {
       Move m;
       while ((m = mp.get_next_move()) != MOVE_NONE)
 
   // Castling moves
   if (movestr == "O-O-O" || movestr == "O-O-O+")
   {
       Move m;
       while ((m = mp.get_next_move()) != MOVE_NONE)

-          if (move_is_long_castle(m) && pos.pl_move_is_legal(m))
+          if (move_is_long_castle(m) && pos.pl_move_is_legal(m, pinned))

               return m;
 
       return MOVE_NONE;
               return m;
 
       return MOVE_NONE;


@@ -157,7 +158,7 @@ Move move_from_san(const Position& pos, const string& movestr) {
   {
       Move m;
       while ((m = mp.get_next_move()) != MOVE_NONE)
   {
       Move m;
       while ((m = mp.get_next_move()) != MOVE_NONE)

-          if (move_is_short_castle(m) && pos.pl_move_is_legal(m))
+          if (move_is_short_castle(m) && pos.pl_move_is_legal(m, pinned))

               return m;
 
     return MOVE_NONE;
               return m;
 
     return MOVE_NONE;


@@ -367,11 +368,12 @@ namespace {
         return AMBIGUITY_NONE;
 
     MovePicker mp = MovePicker(pos, MOVE_NONE, OnePly, H);
         return AMBIGUITY_NONE;
 
     MovePicker mp = MovePicker(pos, MOVE_NONE, OnePly, H);

+    Bitboard pinned = pos.pinned_pieces(pos.side_to_move());

     Move mv, moveList[8];
 
     int n = 0;
     while ((mv = mp.get_next_move()) != MOVE_NONE)
     Move mv, moveList[8];
 
     int n = 0;
     while ((mv = mp.get_next_move()) != MOVE_NONE)

-        if (move_to(mv) == to && pos.piece_on(move_from(mv)) == pc && pos.pl_move_is_legal(mv))
+        if (move_to(mv) == to && pos.piece_on(move_from(mv)) == pc && pos.pl_move_is_legal(mv, pinned))

             moveList[n++] = mv;
 
     if (n == 1)
             moveList[n++] = mv;
 
     if (n == 1)