X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovegen.cpp;h=7cc532aa6e9a6d4a9abdf2cc13e0effb54a18a67;hp=9474bb762f2505589ec14fafdc6a02ceac43efa1;hb=c1257d45b2d8e754572454fb35d676de78f07418;hpb=c852a940094d4f685d7efa4d14ab7e95ddf7ebd2

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 9474bb76..7cc532aa 100644
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -36,13 +36,28 @@ namespace {
   int generate_black_pawn_captures(const Position&, MoveStack*);
   int generate_white_pawn_noncaptures(const Position&, MoveStack*);
   int generate_black_pawn_noncaptures(const Position&, MoveStack*);
-  int generate_knight_moves(const Position&, MoveStack*, Color side, Bitboard t);
-  int generate_bishop_moves(const Position&, MoveStack*, Color side, Bitboard t);
-  int generate_rook_moves(const Position&, MoveStack*, Color side, Bitboard t);
-  int generate_queen_moves(const Position&, MoveStack*, Color side, Bitboard t);
-  int generate_king_moves(const Position&, MoveStack*, Square from, Bitboard t);
+  int generate_piece_moves(PieceType, const Position&, MoveStack*, Color side, Bitboard t);
   int generate_castle_moves(const Position&, MoveStack*, Color us);
 
+  int generate_piece_checks(PieceType pce, const Position& pos, Bitboard target,
+                            Bitboard dc, Square ksq, MoveStack* mlist, int n);
+
+  inline Bitboard next_row_white(Bitboard b) { return b << 8; }
+  inline Bitboard next_row_black(Bitboard b) { return b >> 8; }
+
+  struct PawnOffsets {
+
+      Bitboard Rank3BB;
+      Bitboard Rank8BB;
+      SquareDelta DELTA_N;
+      Color them;
+      Bitboard (*next_row_fn)(Bitboard b);
+  };
+  const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, DELTA_N, BLACK, &next_row_white };
+  const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, DELTA_S, WHITE, &next_row_black };
+
+  int generate_pawn_checks(const PawnOffsets& ofs, const Position& pos, Bitboard dc,
+                           Square ksq, MoveStack* mlist, int n);
 }
 
 
@@ -68,11 +83,9 @@ int generate_captures(const Position& pos, MoveStack* mlist) {
   else
       n = generate_black_pawn_captures(pos, mlist);
 
-  n += generate_knight_moves(pos, mlist+n, us, target);
-  n += generate_bishop_moves(pos, mlist+n, us, target);
-  n += generate_rook_moves(pos, mlist+n, us, target);
-  n += generate_queen_moves(pos, mlist+n, us, target);
-  n += generate_king_moves(pos, mlist+n, pos.king_square(us), target);
+  for (PieceType pce = KNIGHT; pce <= KING; pce++)
+      n += generate_piece_moves(pce, pos, mlist+n, us, target);
+
   return n;
 }
 
@@ -94,11 +107,9 @@ int generate_noncaptures(const Position& pos, MoveStack *mlist) {
   else
       n = generate_black_pawn_noncaptures(pos, mlist);
 
-  n += generate_knight_moves(pos, mlist+n, us, target);
-  n += generate_bishop_moves(pos, mlist+n, us, target);
-  n += generate_rook_moves(pos, mlist+n, us, target);
-  n += generate_queen_moves(pos, mlist+n, us, target);
-  n += generate_king_moves(pos, mlist+n, pos.king_square(us), target);
+  for (PieceType pce = KNIGHT; pce <= KING; pce++)
+      n += generate_piece_moves(pce, pos, mlist+n, us, target);
+
   n += generate_castle_moves(pos, mlist+n, us);
   return n;
 }
@@ -113,216 +124,47 @@ int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
   assert(pos.is_ok());
   assert(!pos.is_check());
 
-  Color us, them;
-  Square ksq, from, to;
-  Bitboard empty, checkSqs, b1, b2, b3;
+  Color us = pos.side_to_move();
+  Square ksq = pos.king_square(opposite_color(us));
   int n = 0;
 
-  us = pos.side_to_move();
-  them = opposite_color(us);
-
-  ksq = pos.king_square(them);
-  assert(pos.piece_on(ksq) == king_of_color(them));
+  assert(pos.piece_on(ksq) == king_of_color(opposite_color(us)));
 
   dc = pos.discovered_check_candidates(us);
-  empty = pos.empty_squares();
-  
-  // Pawn moves.  This is somewhat messy, and we use separate code for white
-  // and black, because we can't shift by negative numbers in C/C++.  :-(
-
-  if (us == WHITE)
-  {
-    // Pawn moves which give 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.
-
-    // Find all friendly pawns not on the enemy king's file:
-    b1 = pos.pawns(us) & ~file_bb(ksq);
-
-    // Discovered checks, single pawn pushes:
-    b2 = b3 = ((b1 & dc) << 8) & ~Rank8BB & empty;
-    while(b3) {
-      to = pop_1st_bit(&b3);
-      mlist[n++].move = make_move(to - DELTA_N, to);
-    }
-
-    // Discovered checks, double pawn pushes:
-    b3 = ((b2 & Rank3BB) << 8) & empty;
-    while(b3) {
-      to = pop_1st_bit(&b3);
-      mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
-    }
 
-    // Direct checks.  These are possible only for pawns on neighboring files
-    // of the enemy king:
-
-    b1 &= (~dc & neighboring_files_bb(ksq));
-
-    // Direct checks, single pawn pushes:
-    b2 = (b1 << 8) & empty;
-    b3 = b2 & pos.black_pawn_attacks(ksq);
-    while(b3) {
-      to = pop_1st_bit(&b3);
-      mlist[n++].move = make_move(to - DELTA_N, to);
-    }
-
-    // Direct checks, double pawn pushes:
-    b3 = ((b2 & Rank3BB) << 8) & empty & pos.black_pawn_attacks(ksq);
-    while(b3) {
-      to = pop_1st_bit(&b3);
-      mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
-    }
-  }
-  else { // (us == BLACK)
-
-    // Pawn moves which give 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.
-
-    // Find all friendly pawns not on the enemy king's file:
-    b1 = pos.pawns(us) & ~file_bb(ksq);
-
-    // Discovered checks, single pawn pushes:
-    b2 = b3 = ((b1 & dc) >> 8) & ~Rank1BB & empty;
-    while(b3) {
-      to = pop_1st_bit(&b3);
-      mlist[n++].move = make_move(to - DELTA_S, to);
-    }
-
-    // Discovered checks, double pawn pushes:
-    b3 = ((b2 & Rank6BB) >> 8) & empty;
-    while(b3) {
-      to = pop_1st_bit(&b3);
-      mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
-    }
-
-    // Direct checks.  These are possible only for pawns on neighboring files
-    // of the enemy king:
-
-    b1 &= (~dc & neighboring_files_bb(ksq));
-
-    // Direct checks, single pawn pushes:
-    b2 = (b1 >> 8) & empty;
-    b3 = b2 & pos.white_pawn_attacks(ksq);
-    while(b3) {
-      to = pop_1st_bit(&b3);
-      mlist[n++].move = make_move(to - DELTA_S, to);
-    }
-
-    // Direct checks, double pawn pushes:
-    b3 = ((b2 & Rank6BB) >> 8) & empty & pos.black_pawn_attacks(ksq);
-    while(b3) {
-      to = pop_1st_bit(&b3);
-      mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
-    }
-  }
-
-  // Knight moves
-  b1 = pos.knights(us);
-  if(b1) {
-    // Discovered knight checks:
-    b2 = b1 & dc;
-    while(b2) {
-      from = pop_1st_bit(&b2);
-      b3 = pos.knight_attacks(from) & empty;
-      while(b3) {
-        to = pop_1st_bit(&b3);
-        mlist[n++].move = make_move(from, to);
-      }
-    }
-    
-    // Direct knight checks:
-    b2 = b1 & ~dc;
-    checkSqs = pos.knight_attacks(ksq) & empty;
-    while(b2) {
-      from = pop_1st_bit(&b2);
-      b3 = pos.knight_attacks(from) & checkSqs;
-      while(b3) {
-        to = pop_1st_bit(&b3);
-        mlist[n++].move = make_move(from, to);
-      }
-    }
-  }
+  // Pawn moves
+  if (us == WHITE)    
+     n = generate_pawn_checks(WhitePawnOffsets, pos, dc, ksq, mlist, 0);
+  else
+     n = generate_pawn_checks(BlackPawnOffsets, pos, dc, ksq, mlist, 0);
 
-  // Bishop moves
-  b1 = pos.bishops(us);
-  if(b1) {
-    // Discovered bishop checks:
-    b2 = b1 & dc;
-    while(b2) {
-      from = pop_1st_bit(&b2);
-      b3 = pos.bishop_attacks(from) & empty;
-      while(b3) {
-        to = pop_1st_bit(&b3);
-        mlist[n++].move = make_move(from, to);
-      }
-    }
-    
-    // Direct bishop checks:
-    b2 = b1 & ~dc;
-    checkSqs = pos.bishop_attacks(ksq) & empty;
-    while(b2) {
-      from = pop_1st_bit(&b2);
-      b3 = pos.bishop_attacks(from) & checkSqs;
-      while(b3) {
-        to = pop_1st_bit(&b3);
-        mlist[n++].move = make_move(from, to);
-      }
-    }
-  }
+  // Pieces moves
+  Bitboard b = pos.knights(us);
+  if (b)
+      n = generate_piece_checks(KNIGHT, pos, b, dc, ksq, mlist, n);
 
-  // Rook moves
-  b1 = pos.rooks(us);
-  if(b1) {
-    // Discovered rook checks:
-    b2 = b1 & dc;
-    while(b2) {
-      from = pop_1st_bit(&b2);
-      b3 = pos.rook_attacks(from) & empty;
-      while(b3) {
-        to = pop_1st_bit(&b3);
-        mlist[n++].move = make_move(from, to);
-      }
-    }
-    
-    // Direct rook checks:
-    b2 = b1 & ~dc;
-    checkSqs = pos.rook_attacks(ksq) & empty;
-    while(b2) {
-      from = pop_1st_bit(&b2);
-      b3 = pos.rook_attacks(from) & checkSqs;
-      while(b3) {
-        to = pop_1st_bit(&b3);
-        mlist[n++].move = make_move(from, to);
-      }
-    }
-  }
+  b = pos.bishops(us);
+  if (b)
+      n = generate_piece_checks(BISHOP, pos, b, dc, ksq, mlist, n);
 
-  // Queen moves
-  b1 = pos.queens(us);
-  if(b1) {
-    // Discovered queen checks are impossible!
+  b = pos.rooks(us);
+  if (b)
+      n = generate_piece_checks(ROOK, pos, b, dc, ksq, mlist, n);
 
-    // Direct queen checks:
-    checkSqs = pos.queen_attacks(ksq) & empty;
-    while(b1) {
-      from = pop_1st_bit(&b1);
-      b2 = pos.queen_attacks(from) & checkSqs;
-      while(b2) {
-        to = pop_1st_bit(&b2);
-        mlist[n++].move = make_move(from, to);
-      }
-    }
-  }
+  b = pos.queens(us);
+  if (b)
+      n = generate_piece_checks(QUEEN, pos, b, dc, ksq, mlist, n);
 
   // King moves
-  from = pos.king_square(us);
-  if(bit_is_set(dc, from)) {
-    b1 = pos.king_attacks(from) & empty & ~QueenPseudoAttacks[ksq];
-    while(b1) {
-      to = pop_1st_bit(&b1);
-      mlist[n++].move = make_move(from, to);
-    }
+  Square from = pos.king_square(us);
+  if (bit_is_set(dc, from))
+  {
+      b = pos.king_attacks(from) & pos.empty_squares() & ~QueenPseudoAttacks[ksq];
+      while (b)
+      {
+          Square to = pop_1st_bit(&b);
+          mlist[n++].move = make_move(from, to);
+      }
   }
 
   // TODO: Castling moves!
@@ -779,132 +621,145 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) {
 namespace {
 
   int generate_white_pawn_captures(const Position &pos, MoveStack *mlist) {
+
     Bitboard pawns = pos.pawns(WHITE);
     Bitboard enemyPieces = pos.pieces_of_color(BLACK);
-    Bitboard b1, b2;
     Square sq;
     int n = 0;
 
-    // Captures in the a1-h8 direction:
-    b1 = (pawns << 9) & ~FileABB & enemyPieces;
+    // Captures in the a1-h8 direction
+    Bitboard b1 = (pawns << 9) & ~FileABB & enemyPieces;
 
-    // Promotions:
-    b2 = b1 & Rank8BB;
-    while(b2) {
-      sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, QUEEN);
+    // Capturing promotions
+    Bitboard b2 = b1 & Rank8BB;
+    while (b2)
+    {
+        sq = pop_1st_bit(&b2);
+        mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, QUEEN);
     }
 
-    // Non-promotions:
+    // Capturing non-promotions
     b2 = b1 & ~Rank8BB;
-    while(b2) {
-      sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_move(sq - DELTA_NE, sq);
+    while (b2)
+    {
+        sq = pop_1st_bit(&b2);
+        mlist[n++].move = make_move(sq - DELTA_NE, sq);
     }
 
-    // Captures in the h1-a8 direction:
+    // Captures in the h1-a8 direction
     b1 = (pawns << 7) & ~FileHBB & enemyPieces;
 
-    // Promotions:
+    // Capturing promotions
     b2 = b1 & Rank8BB;
-    while(b2) {
-      sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, QUEEN);
+    while (b2)
+    {
+        sq = pop_1st_bit(&b2);
+        mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, QUEEN);
     }
 
-    // Non-promotions:
+    // Capturing non-promotions
     b2 = b1 & ~Rank8BB;
-    while(b2) {
-      sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_move(sq - DELTA_NW, sq);
+    while (b2)
+    {
+        sq = pop_1st_bit(&b2);
+        mlist[n++].move = make_move(sq - DELTA_NW, sq);
     }
 
-    // Non-capturing promotions:
+    // Non-capturing promotions
     b1 = (pawns << 8) & pos.empty_squares() & Rank8BB;
-    while(b1)  {
-      sq = pop_1st_bit(&b1);
-      mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, QUEEN);
-    }
-
-    // En passant captures:
-    if(pos.ep_square() != SQ_NONE) {
-      assert(square_rank(pos.ep_square()) == RANK_6);
-      b1 = pawns & pos.black_pawn_attacks(pos.ep_square());
-      assert(b1 != EmptyBoardBB);
-      while(b1) {
+    while (b1)
+    {
         sq = pop_1st_bit(&b1);
-        mlist[n++].move = make_ep_move(sq, pos.ep_square());
-      }
+        mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, QUEEN);
     }
 
+    // En passant captures
+    if (pos.ep_square() != SQ_NONE)
+    {
+        assert(square_rank(pos.ep_square()) == RANK_6);
+        b1 = pawns & pos.black_pawn_attacks(pos.ep_square());
+        assert(b1 != EmptyBoardBB);
+        while (b1)
+        {
+            sq = pop_1st_bit(&b1);
+            mlist[n++].move = make_ep_move(sq, pos.ep_square());
+        }
+    }
     return n;
   }
 
 
   int generate_black_pawn_captures(const Position &pos, MoveStack *mlist) {
+
     Bitboard pawns = pos.pawns(BLACK);
     Bitboard enemyPieces = pos.pieces_of_color(WHITE);
-    Bitboard b1, b2;
     Square sq;
     int n = 0;
 
-    // Captures in the a8-h1 direction:
-    b1 = (pawns >> 7) & ~FileABB & enemyPieces;
+    // Captures in the a8-h1 direction
+    Bitboard b1 = (pawns >> 7) & ~FileABB & enemyPieces;
 
-    // Promotions:
-    b2 = b1 & Rank1BB;
-    while(b2) {
-      sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, QUEEN);
+    // Capturing promotions
+    Bitboard b2 = b1 & Rank1BB;
+    while (b2)
+    {
+        sq = pop_1st_bit(&b2);
+        mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, QUEEN);
     }
 
-    // Non-promotions:
+    // Capturing non-promotions
     b2 = b1 & ~Rank1BB;
-    while(b2) {
-      sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_move(sq - DELTA_SE, sq);
+    while (b2)
+    {
+        sq = pop_1st_bit(&b2);
+        mlist[n++].move = make_move(sq - DELTA_SE, sq);
     }
 
-    // Captures in the h8-a1 direction:
+    // Captures in the h8-a1 direction
     b1 = (pawns >> 9) & ~FileHBB & enemyPieces;
 
-    // Promotions:
+    // Capturing promotions
     b2 = b1 & Rank1BB;
-    while(b2) {
-      sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, QUEEN);
+    while (b2)
+    {
+        sq = pop_1st_bit(&b2);
+        mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, QUEEN);
     }
 
-    // Non-promotions:
+    // Capturing Non-promotions
     b2 = b1 & ~Rank1BB;
-    while(b2) {
-      sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_move(sq - DELTA_SW, sq);
+    while (b2)
+    {
+        sq = pop_1st_bit(&b2);
+        mlist[n++].move = make_move(sq - DELTA_SW, sq);
     }
 
-    // Non-capturing promotions:
+    // Non-capturing promotions
     b1 = (pawns >> 8) & pos.empty_squares() & Rank1BB;
-    while(b1)  {
-      sq = pop_1st_bit(&b1);
-      mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, QUEEN);
-    }
-
-    // En passant captures:
-    if(pos.ep_square() != SQ_NONE) {
-      assert(square_rank(pos.ep_square()) == RANK_3);
-      b1 = pawns & pos.white_pawn_attacks(pos.ep_square());
-      assert(b1 != EmptyBoardBB);
-      while(b1) {
+    while (b1)
+    {
         sq = pop_1st_bit(&b1);
-        mlist[n++].move = make_ep_move(sq, pos.ep_square());
-      }
+        mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, QUEEN);
     }
 
+    // En passant captures
+    if (pos.ep_square() != SQ_NONE)
+    {
+        assert(square_rank(pos.ep_square()) == RANK_3);
+        b1 = pawns & pos.white_pawn_attacks(pos.ep_square());
+        assert(b1 != EmptyBoardBB);
+        while (b1)
+        {
+            sq = pop_1st_bit(&b1);
+            mlist[n++].move = make_ep_move(sq, pos.ep_square());
+        }
+    }
     return n;
   }
-    
+
 
   int generate_white_pawn_noncaptures(const Position &pos, MoveStack *mlist) {
+
     Bitboard pawns = pos.pawns(WHITE);
     Bitboard enemyPieces = pos.pieces_of_color(BLACK);
     Bitboard emptySquares = pos.empty_squares();
@@ -1008,149 +863,174 @@ namespace {
   }
 
 
-  int generate_knight_moves(const Position &pos, MoveStack *mlist, 
-                            Color side, Bitboard target) {
+  int generate_piece_moves(PieceType piece, const Position &pos, MoveStack *mlist, 
+                           Color side, Bitboard target) {
+
+    const Piece_attacks_fn mem_fn = piece_attacks_fn[piece];
     Square from, to;
     Bitboard b;
-    int i, n = 0;
-
-    for(i = 0; i < pos.knight_count(side); i++) {
-      from = pos.knight_list(side, i);
-      b = pos.knight_attacks(from) & target;
-      while(b) {
-        to = pop_1st_bit(&b);
-        mlist[n++].move = make_move(from, to);
-      }
+    int n = 0;
+
+    for (int i = 0; i < pos.piece_count(side, piece); i++)
+    {
+        from = pos.piece_list(side, piece, i);
+        b = (pos.*mem_fn)(from) & target;
+        while (b)
+        {
+            to = pop_1st_bit(&b);
+            mlist[n++].move = make_move(from, to);
+        }
     }
     return n;
   }
 
 
-  int generate_bishop_moves(const Position &pos, MoveStack *mlist, 
-                            Color side, Bitboard target) {
-    Square from, to;
-    Bitboard b;
-    int i, n = 0;
-
-    for(i = 0; i < pos.bishop_count(side); i++) {
-      from = pos.bishop_list(side, i);
-      b = pos.bishop_attacks(from) & target;
-      while(b) {
-        to = pop_1st_bit(&b);
-        mlist[n++].move = make_move(from, to);
-      }
-    }
-    return n;
-  }
+  int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) {
+
+    int n = 0;
 
+    if (pos.can_castle(us))
+    {
+        Color them = opposite_color(us);
+        Square ksq = pos.king_square(us);        
 
-  int generate_rook_moves(const Position &pos, MoveStack *mlist, 
-                          Color side, Bitboard target) {
-    Square from, to;
-    Bitboard b;
-    int i, n = 0;
-
-    for(i = 0; i < pos.rook_count(side); i++) {
-      from = pos.rook_list(side, i);
-      b = pos.rook_attacks(from) & target;
-      while(b) {
-        to = pop_1st_bit(&b);
-        mlist[n++].move = make_move(from, to);
-      }
-    }
-    return n;
-  }
+        assert(pos.piece_on(ksq) == king_of_color(us));
 
+        if (pos.can_castle_kingside(us))
+        {
+            Square rsq = pos.initial_kr_square(us);
+            Square g1 = relative_square(us, SQ_G1);
+            Square f1 = relative_square(us, SQ_F1);
+            Square s;
+            bool illegal = false;
 
-  int generate_queen_moves(const Position &pos, MoveStack *mlist, 
-                           Color side, Bitboard target) {
-    Square from, to;
-    Bitboard b;
-    int i, n = 0;
-
-    for(i = 0; i < pos.queen_count(side); i++) {
-      from = pos.queen_list(side, i);
-      b = pos.queen_attacks(from) & target;
-      while(b) {
-        to = pop_1st_bit(&b);
-        mlist[n++].move = make_move(from, to);
+            assert(pos.piece_on(rsq) == rook_of_color(us));
+
+            for (s = Min(ksq, g1); s <= Max(ksq, g1); s++)
+                if (  (s != ksq && s != rsq && pos.square_is_occupied(s))
+                    || pos.square_is_attacked(s, them))
+                    illegal = true;
+
+            for (s = Min(rsq, f1); s <= Max(rsq, f1); s++)
+                if (s != ksq && s != rsq && pos.square_is_occupied(s))
+                    illegal = true;
+
+            if (!illegal)
+                mlist[n++].move = make_castle_move(ksq, rsq);
+      }
+
+      if (pos.can_castle_queenside(us))
+      {
+          Square rsq = pos.initial_qr_square(us);
+          Square c1 = relative_square(us, SQ_C1);
+          Square d1 = relative_square(us, SQ_D1);
+          Square s;
+          bool illegal = false;        
+
+          assert(pos.piece_on(rsq) == rook_of_color(us));
+
+          for (s = Min(ksq, c1); s <= Max(ksq, c1); s++)
+              if (  (s != ksq && s != rsq && pos.square_is_occupied(s))
+                  || pos.square_is_attacked(s, them))
+                  illegal = true;
+
+          for (s = Min(rsq, d1); s <= Max(rsq, d1); s++)
+              if (s != ksq && s != rsq && pos.square_is_occupied(s))
+                  illegal = true;
+
+        if (   square_file(rsq) == FILE_B
+            && (   pos.piece_on(relative_square(us, SQ_A1)) == rook_of_color(them)
+                || pos.piece_on(relative_square(us, SQ_A1)) == queen_of_color(them)))
+            illegal = true;
+                         
+        if (!illegal)
+            mlist[n++].move = make_castle_move(ksq, rsq);
       }
     }
     return n;
   }
 
+  int generate_piece_checks(PieceType pce, const Position& pos, Bitboard target,
+                          Bitboard dc, Square ksq, MoveStack* mlist, int n) {
+
+    const Piece_attacks_fn mem_fn = piece_attacks_fn[pce];
+
+    // Discovered checks
+    Bitboard b = target & dc;
+    while (b)
+    {
+        Square from = pop_1st_bit(&b);
+        Bitboard bb = (pos.*mem_fn)(from) & pos.empty_squares();
+        while (bb)
+        {
+            Square to = pop_1st_bit(&bb);
+            mlist[n++].move = make_move(from, to);
+        }
+    }
 
-  int generate_king_moves(const Position &pos, MoveStack *mlist, 
-                          Square from, Bitboard target) {
-    Square to;
-    Bitboard b;
-    int n = 0;
-    
-    b = pos.king_attacks(from) & target;
-    while(b) {
-      to = pop_1st_bit(&b);
-      mlist[n++].move = make_move(from, to);
+    // Direct checks
+    b = target & ~dc;
+    Bitboard checkSqs = (pos.*mem_fn)(ksq) & pos.empty_squares();
+    while (b)
+    {
+        Square from = pop_1st_bit(&b);
+        Bitboard bb = (pos.*mem_fn)(from) & checkSqs;
+        while (bb)
+        {
+            Square to = pop_1st_bit(&bb);
+            mlist[n++].move = make_move(from, to);
+        }
     }
     return n;
   }
 
+  int generate_pawn_checks(const PawnOffsets& ofs, const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist, int n)
+  {
+    // Pawn moves which give 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.
+    Bitboard empty = pos.empty_squares();
 
-  int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) {
-    int n = 0;
-
-    if(pos.can_castle(us)) {
-      Color them = opposite_color(us);
-      Square ksq = pos.king_square(us);
-      assert(pos.piece_on(ksq) == king_of_color(us));
-      
-      if(pos.can_castle_kingside(us)) {
-        Square rsq = pos.initial_kr_square(us);
-        Square g1 = relative_square(us, SQ_G1);
-        Square f1 = relative_square(us, SQ_F1);
-        Square s;
-        bool illegal = false;
-
-        assert(pos.piece_on(rsq) == rook_of_color(us));
+    // Find all friendly pawns not on the enemy king's file
+    Bitboard b1 = pos.pawns(pos.side_to_move()) & ~file_bb(ksq), b2, b3;
 
-        for(s = Min(ksq, g1); s <= Max(ksq, g1); s++)
-          if((s != ksq && s != rsq && pos.square_is_occupied(s))
-             || pos.square_is_attacked(s, them))
-            illegal = true;
-        for(s = Min(rsq, f1); s <= Max(rsq, f1); s++)
-          if(s != ksq && s != rsq && pos.square_is_occupied(s))
-            illegal = true;
+    // Discovered checks, single pawn pushes
+    b2 = b3 = (ofs.next_row_fn)(b1 & dc) & ~ofs.Rank8BB & empty;
+    while (b3)
+    {
+        Square to = pop_1st_bit(&b3);
+        mlist[n++].move = make_move(to - ofs.DELTA_N, to);
+    }
 
-        if(!illegal)
-          mlist[n++].move = make_castle_move(ksq, rsq);
-      }
+    // Discovered checks, double pawn pushes
+    b3 = (ofs.next_row_fn)(b2 & ofs.Rank3BB) & empty;
+    while (b3)
+    {
+        Square to = pop_1st_bit(&b3);
+        mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
+    }
 
-      if(pos.can_castle_queenside(us)) {
-        Square rsq = pos.initial_qr_square(us);
-        Square c1 = relative_square(us, SQ_C1);
-        Square d1 = relative_square(us, SQ_D1);
-        Square s;
-        bool illegal = false;
+    // Direct checks. These are possible only for pawns on neighboring files
+    // of the enemy king
 
-        assert(pos.piece_on(rsq) == rook_of_color(us));
+    b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
 
-        for(s = Min(ksq, c1); s <= Max(ksq, c1); s++)
-          if((s != ksq && s != rsq && pos.square_is_occupied(s))
-             || pos.square_is_attacked(s, them))
-            illegal = true;
-        for(s = Min(rsq, d1); s <= Max(rsq, d1); s++)
-          if(s != ksq && s != rsq && pos.square_is_occupied(s))
-            illegal = true;
-        if(square_file(rsq) == FILE_B &&
-           (pos.piece_on(relative_square(us, SQ_A1)) == rook_of_color(them) ||
-            pos.piece_on(relative_square(us, SQ_A1)) == queen_of_color(them)))
-           illegal = true;
-                         
-        if(!illegal)
-          mlist[n++].move = make_castle_move(ksq, rsq);
-      }
+    // Direct checks, single pawn pushes
+    b2 = (ofs.next_row_fn)(b1) & empty;
+    b3 = b2 & pos.pawn_attacks(ofs.them, ksq);
+    while (b3)
+    {
+        Square to = pop_1st_bit(&b3);
+        mlist[n++].move = make_move(to - ofs.DELTA_N, to);
     }
 
+    // Direct checks, double pawn pushes
+    b3 = (ofs.next_row_fn)(b2 & ofs.Rank3BB) & empty & pos.pawn_attacks(ofs.them, ksq);
+    while (b3)
+    {
+        Square to = pop_1st_bit(&b3);
+        mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
+    }
     return n;
   }
-    
 }