X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovegen.cpp;h=e7c78bb6e7b43cbf33f477aa635c304438a4dcf8;hp=cf938dadc27d89a93b78b780e6a884f8ccd03d5e;hb=b145e995592c95014a519e91845379d0f9f89ac6;hpb=72289fcfab9750db76d9dab730a7f0c5f405a236

diff --git a/src/movegen.cpp b/src/movegen.cpp
index cf938dad..e7c78bb6 100644
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -1,17 +1,17 @@
 /*
-  Glaurung, a UCI chess playing engine.
-  Copyright (C) 2004-2008 Tord Romstad
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008 Marco Costalba
 
-  Glaurung is free software: you can redistribute it and/or modify
+  Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
-  
-  Glaurung is distributed in the hope that it will be useful,
+
+  Stockfish is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
-  
+
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
@@ -32,36 +32,73 @@
 
 namespace {
 
-  inline Bitboard forward_white(Bitboard b) { return b << 8; }
-  inline Bitboard forward_right_white(Bitboard b) { return b << 9; }
-  inline Bitboard forward_left_white(Bitboard b) { return b << 7; }
-
-  inline Bitboard forward_black(Bitboard b) { return b >> 8; }
-  inline Bitboard forward_right_black(Bitboard b) { return b >> 7; }
-  inline Bitboard forward_left_black(Bitboard b) { return b >> 9; }
-
-  struct PawnOffsets {
-
-      Bitboard Rank3BB, Rank8BB;
-      SquareDelta DELTA_N, DELTA_NE, DELTA_NW;
-      Color us, them;
-      typedef Bitboard (*Shift_fn)(Bitboard b);
-      Shift_fn forward, forward_left, forward_right;
-  };
-  const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, DELTA_N, DELTA_NE, DELTA_NW, WHITE,
-                                         BLACK, &forward_white, forward_left_white, forward_right_white };
-
-  const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, DELTA_S, DELTA_SE, DELTA_SW, BLACK,
-                                         WHITE, &forward_black, &forward_left_black, &forward_right_black };
-  
-  int generate_pawn_captures(const PawnOffsets&, const Position&, MoveStack*);  
-  int generate_pawn_noncaptures(const PawnOffsets&, const Position&, MoveStack*);
-  int generate_pawn_checks(const PawnOffsets&, const Position&, Bitboard dc, Square ksq, MoveStack*, int n);
-  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);
+  // Function
+  int generate_castle_moves(const Position&, MoveStack*);
+
+  // Template generate_pawn_captures() with specializations
+  template<Color, Color, Bitboard, SquareDelta, SquareDelta, SquareDelta>
+  int do_generate_pawn_captures(const Position& pos, MoveStack* mlist);
+
+  template<Color>
+  inline int generate_pawn_captures(const Position& p, MoveStack* m) {
+      return do_generate_pawn_captures<WHITE, BLACK, Rank8BB, DELTA_NE, DELTA_NW, DELTA_N>(p, m);
+  }
+  template<>
+  inline int generate_pawn_captures<BLACK>(const Position& p, MoveStack* m) {
+      return do_generate_pawn_captures<BLACK, WHITE, Rank1BB, DELTA_SE, DELTA_SW, DELTA_S>(p, m);
+  }
+
+  // Template generate_pawn_noncaptures() with specializations
+  template<Color, Color, Bitboard, Bitboard, SquareDelta, SquareDelta, SquareDelta>
+  int do_generate_pawn_noncaptures(const Position& pos, MoveStack* mlist);
+
+  template<Color>
+  inline int generate_pawn_noncaptures(const Position& p, MoveStack* m) {
+      return do_generate_pawn_noncaptures<WHITE, BLACK, Rank8BB, Rank3BB, DELTA_NE, DELTA_NW, DELTA_N>(p, m);
+  }
+  template<>
+  inline int generate_pawn_noncaptures<BLACK>(const Position& p, MoveStack* m) {
+      return do_generate_pawn_noncaptures<BLACK, WHITE, Rank1BB, Rank6BB, DELTA_SE, DELTA_SW, DELTA_S>(p, m);
+  }
+
+  // Template generate_pawn_blocking_evasions() with specializations
+  template<Color Us, Bitboard, Bitboard, SquareDelta>
+  int do_generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned,
+                                         Bitboard blockSquares, MoveStack* mlist);
+  template<Color>
+  inline int generate_pawn_blocking_evasions(const Position& p, Bitboard np, Bitboard bs, MoveStack* m) {
+      return do_generate_pawn_blocking_evasions<WHITE, Rank8BB, Rank3BB, DELTA_N>(p, np, bs, m);
+  }
+  template<>
+  inline int generate_pawn_blocking_evasions<BLACK>(const Position& p, Bitboard np, Bitboard bs, MoveStack* m) {
+      return do_generate_pawn_blocking_evasions<BLACK, Rank1BB, Rank6BB, DELTA_S>(p, np, bs, m);
+  }
+
+  // Template generate_pawn_checks() with specializations
+  template<Color, Color, Bitboard, Bitboard, SquareDelta>
+  int do_generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*);
+
+  template<Color>
+  inline int generate_pawn_checks(const Position& p, Bitboard dc, Square ksq, MoveStack* m) {
+      return do_generate_pawn_checks<WHITE, BLACK, Rank8BB, Rank3BB, DELTA_N>(p, dc, ksq, m);
+  }
+  template<>
+  inline int generate_pawn_checks<BLACK>(const Position& p, Bitboard dc, Square ksq, MoveStack* m) {
+      return do_generate_pawn_checks<BLACK, WHITE, Rank1BB, Rank6BB, DELTA_S>(p, dc, ksq, m);
+  }
+
+  // non-pawn templates
+  template<PieceType>
+  int generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard);
+  template<>
+  int generate_piece_moves<KING>(const Position& pos, MoveStack* mlist, Color us, Bitboard target);
+
+  template<PieceType>
+  int generate_piece_checks(const Position&, Bitboard, Bitboard, Square, MoveStack*);
+  int generate_piece_checks_king(const Position&, Square, Bitboard, Square, MoveStack*);
+
+  template<PieceType>
+  int generate_piece_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*);
 }
 
 
@@ -83,18 +120,20 @@ int generate_captures(const Position& pos, MoveStack* mlist) {
   int n;
 
   if (us == WHITE)
-      n = generate_pawn_captures(WhitePawnOffsets, pos, mlist);
+      n = generate_pawn_captures<WHITE>(pos, mlist);
   else
-      n = generate_pawn_captures(BlackPawnOffsets, pos, mlist);
-
-  for (PieceType pce = KNIGHT; pce <= KING; pce++)
-      n += generate_piece_moves(pce, pos, mlist+n, us, target);
+      n = generate_pawn_captures<BLACK>(pos, mlist);
 
+  n += generate_piece_moves<KNIGHT>(pos, mlist+n, us, target);
+  n += generate_piece_moves<BISHOP>(pos, mlist+n, us, target);
+  n += generate_piece_moves<ROOK>(pos, mlist+n, us, target);
+  n += generate_piece_moves<QUEEN>(pos, mlist+n, us, target);
+  n += generate_piece_moves<KING>(pos, mlist+n, us, target);
   return n;
 }
 
 
-/// generate_noncaptures() generates all pseudo-legal non-captures and 
+/// generate_noncaptures() generates all pseudo-legal non-captures and
 /// underpromotions.  The return value is the number of moves generated.
 
 int generate_noncaptures(const Position& pos, MoveStack *mlist) {
@@ -107,21 +146,23 @@ int generate_noncaptures(const Position& pos, MoveStack *mlist) {
   int n;
 
   if (us == WHITE)
-      n = generate_pawn_noncaptures(WhitePawnOffsets, pos, mlist);
+      n = generate_pawn_noncaptures<WHITE>(pos, mlist);
   else
-      n = generate_pawn_noncaptures(BlackPawnOffsets, pos, mlist);
-
-  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);
+      n = generate_pawn_noncaptures<BLACK>(pos, mlist);
+
+  n += generate_piece_moves<KNIGHT>(pos, mlist+n, us, target);
+  n += generate_piece_moves<BISHOP>(pos, mlist+n, us, target);
+  n += generate_piece_moves<ROOK>(pos, mlist+n, us, target);
+  n += generate_piece_moves<QUEEN>(pos, mlist+n, us, target);
+  n += generate_piece_moves<KING>(pos, mlist+n, us, target);
+  n += generate_castle_moves(pos, mlist+n);
   return n;
 }
 
 
 /// generate_checks() generates all pseudo-legal non-capturing, non-promoting
 /// checks, except castling moves (will add this later).  It returns the
-/// number of generated moves.  
+/// number of generated moves.
 
 int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
 
@@ -137,42 +178,33 @@ int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
   dc = pos.discovered_check_candidates(us);
 
   // Pawn moves
-  if (us == WHITE)    
-     n = generate_pawn_checks(WhitePawnOffsets, pos, dc, ksq, mlist, 0);
+  if (us == WHITE)
+     n = generate_pawn_checks<WHITE>(pos, dc, ksq, mlist);
   else
-     n = generate_pawn_checks(BlackPawnOffsets, pos, dc, ksq, mlist, 0);
+     n = generate_pawn_checks<BLACK>(pos, dc, ksq, mlist);
 
   // Pieces moves
   Bitboard b = pos.knights(us);
   if (b)
-      n = generate_piece_checks(KNIGHT, pos, b, dc, ksq, mlist, n);
+      n += generate_piece_checks<KNIGHT>(pos, b, dc, ksq, mlist+n);
 
   b = pos.bishops(us);
   if (b)
-      n = generate_piece_checks(BISHOP, pos, b, dc, ksq, mlist, n);
+      n += generate_piece_checks<BISHOP>(pos, b, dc, ksq, mlist+n);
 
   b = pos.rooks(us);
   if (b)
-      n = generate_piece_checks(ROOK, pos, b, dc, ksq, mlist, n);
+      n += generate_piece_checks<ROOK>(pos, b, dc, ksq, mlist+n);
 
   b = pos.queens(us);
   if (b)
-      n = generate_piece_checks(QUEEN, pos, b, dc, ksq, mlist, n);
+      n += generate_piece_checks<QUEEN>(pos, b, dc, ksq, mlist+n);
 
-  // King moves
-  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);
-      }
-  }
+  // Hopefully we always have a king ;-)
+  n += generate_piece_checks_king(pos, pos.king_square(us), dc, ksq, mlist+n);
 
   // TODO: Castling moves!
-  
+
   return n;
 }
 
@@ -182,235 +214,149 @@ int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
 /// only legal moves.  It returns the number of generated moves.  This
 /// function is very ugly, and needs cleaning up some time later.  FIXME
 
-int generate_evasions(const Position &pos, MoveStack *mlist) {
+int generate_evasions(const Position& pos, MoveStack* mlist) {
 
   assert(pos.is_ok());
   assert(pos.is_check());
 
-  Color us, them;
-  Bitboard checkers = pos.checkers();
-  Bitboard pinned, b1, b2;
-  Square ksq, from, to;
+  Color us = pos.side_to_move();
+  Color them = opposite_color(us);
+  Square ksq = pos.king_square(us);
+  Square from, to;
   int n = 0;
 
-  us = pos.side_to_move();
-  them = opposite_color(us);
-
-  ksq = pos.king_square(us);
   assert(pos.piece_on(ksq) == king_of_color(us));
-  
-  // Generate evasions for king:
-  b1 = pos.king_attacks(ksq) & ~pos.pieces_of_color(us);
-  b2 = pos.occupied_squares();
+
+  // Generate evasions for king
+  Bitboard b1 = pos.piece_attacks<KING>(ksq) & ~pos.pieces_of_color(us);
+  Bitboard b2 = pos.occupied_squares();
   clear_bit(&b2, ksq);
-  while(b1) {
+
+  while (b1)
+  {
     to = pop_1st_bit(&b1);
 
-    // Make sure to is not attacked by the other side.  This is a bit ugly,
-    // because we can't use Position::square_is_attacked.  Instead we use
+    // Make sure to is not attacked by the other side. This is a bit ugly,
+    // because we can't use Position::square_is_attacked. Instead we use
     // the low-level bishop_attacks_bb and rook_attacks_bb with the bitboard
     // b2 (the occupied squares with the king removed) in order to test whether
     // the king will remain in check on the destination square.
-    if(((pos.pawn_attacks(us, to) & pos.pawns(them)) == EmptyBoardBB) &&
-       ((pos.knight_attacks(to) & pos.knights(them)) == EmptyBoardBB) &&
-       ((pos.king_attacks(to) & pos.kings(them)) == EmptyBoardBB) &&
-       ((bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them))
-        == EmptyBoardBB) &&
-       ((rook_attacks_bb(to, b2) & pos.rooks_and_queens(them)) == EmptyBoardBB))
-      mlist[n++].move = make_move(ksq, to);
-  }
+    if (!(   (bishop_attacks_bb(to, b2)     & pos.bishops_and_queens(them))
+          || (rook_attacks_bb(to, b2)       & pos.rooks_and_queens(them))
+          || (pos.piece_attacks<KNIGHT>(to) & pos.knights(them))
+          || (pos.pawn_attacks(us, to)      & pos.pawns(them))
+          || (pos.piece_attacks<KING>(to)   & pos.kings(them))))
 
+        mlist[n++].move = make_move(ksq, to);
+  }
 
-  // Generate evasions for other pieces only if not double check.  We use a
+  // Generate evasions for other pieces only if not double check. We use a
   // simple bit twiddling hack here rather than calling count_1s in order to
   // save some time (we know that pos.checkers() has at most two nonzero bits).
-  if(!(checkers & (checkers - 1))) {
-    Square checksq = first_1(checkers);
-    assert(pos.color_of_piece_on(checksq) == them);
-
-    // Find pinned pieces:
-    pinned = pos.pinned_pieces(us);
-
-    // Generate captures of the checking piece:
-
-    // Pawn captures:
-    b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & ~pinned;
-    while(b1) {
-      from = pop_1st_bit(&b1);
-      if(relative_rank(us, checksq) == RANK_8) {
-        mlist[n++].move = make_promotion_move(from, checksq, QUEEN);
-        mlist[n++].move = make_promotion_move(from, checksq, ROOK);
-        mlist[n++].move = make_promotion_move(from, checksq, BISHOP);
-        mlist[n++].move = make_promotion_move(from, checksq, KNIGHT);
-      }
-      else
-        mlist[n++].move = make_move(from, checksq);
-    }
+  Bitboard checkers = pos.checkers();
 
-    // Knight captures:
-    b1 = pos.knight_attacks(checksq) & pos.knights(us) & ~pinned;
-    while(b1) {
-      from = pop_1st_bit(&b1);
-      mlist[n++].move = make_move(from, checksq);
-    }
+  if (!(checkers & (checkers - 1))) // Only one bit set?
+  {
+      Square checksq = first_1(checkers);
 
-    // Bishop and queen captures:
-    b1 = pos.bishop_attacks(checksq) & pos.bishops_and_queens(us)
-      & ~pinned;
-    while(b1) {
-      from = pop_1st_bit(&b1);
-      mlist[n++].move = make_move(from, checksq);
-    }
+      assert(pos.color_of_piece_on(checksq) == them);
 
-    // Rook and queen captures:
-    b1 = pos.rook_attacks(checksq) & pos.rooks_and_queens(us)
-      & ~pinned;
-    while(b1) {
-      from = pop_1st_bit(&b1);
-      mlist[n++].move = make_move(from, checksq);
-    }
+      // Find pinned pieces
+      Bitboard not_pinned = ~pos.pinned_pieces(us);
 
-    // Blocking check evasions are possible only if the checking piece is
-    // a slider:
-    if(checkers & pos.sliders()) {
-      Bitboard blockSquares = squares_between(checksq, ksq);
-      assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
-
-      // Pawn moves.  Because a blocking evasion can never be a capture, we
-      // only generate pawn pushes.  As so often, the code for pawns is a bit
-      // ugly, and uses separate clauses for white and black pawns. :-(
-      if(us == WHITE) {
-        // Find non-pinned pawns:
-        b1 = pos.pawns(WHITE) & ~pinned;
-
-        // Single pawn pushes.  We don't have to AND with empty squares here,
-        // because the blocking squares will always be empty.
-        b2 = (b1 << 8) & blockSquares;
-        while(b2) {
-          to = pop_1st_bit(&b2);
-          assert(pos.piece_on(to) == EMPTY);
-          if(square_rank(to) == RANK_8) {
-            mlist[n++].move = make_promotion_move(to - DELTA_N, to, QUEEN);
-            mlist[n++].move = make_promotion_move(to - DELTA_N, to, ROOK);
-            mlist[n++].move = make_promotion_move(to - DELTA_N, to, BISHOP);
-            mlist[n++].move = make_promotion_move(to - DELTA_N, to, KNIGHT);
-          }
-          else
-            mlist[n++].move = make_move(to - DELTA_N, to);
-        }
-        // Double pawn pushes.
-        b2 = (((b1 << 8) & pos.empty_squares() & Rank3BB) << 8) & blockSquares;
-        while(b2) {
-          to = pop_1st_bit(&b2);
-          assert(pos.piece_on(to) == EMPTY);
-          assert(square_rank(to) == RANK_4);
-          mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
-        }
-      }
-      else { // (us == BLACK)
-        // Find non-pinned pawns:
-        b1 = pos.pawns(BLACK) & ~pinned;
-
-        // Single pawn pushes.  We don't have to AND with empty squares here,
-        // because the blocking squares will always be empty.
-        b2 = (b1 >> 8) & blockSquares;
-        while(b2) {
-          to = pop_1st_bit(&b2);
-          assert(pos.piece_on(to) == EMPTY);
-          if(square_rank(to) == RANK_1) {
-            mlist[n++].move = make_promotion_move(to - DELTA_S, to, QUEEN);
-            mlist[n++].move = make_promotion_move(to - DELTA_S, to, ROOK);
-            mlist[n++].move = make_promotion_move(to - DELTA_S, to, BISHOP);
-            mlist[n++].move = make_promotion_move(to - DELTA_S, to, KNIGHT);
-          }
-          else
-            mlist[n++].move = make_move(to - DELTA_S, to);
-        }
-        // Double pawn pushes.
-        b2 = (((b1 >> 8) & pos.empty_squares() & Rank6BB) >> 8) & blockSquares;
-        while(b2) {
-          to = pop_1st_bit(&b2);
-          assert(pos.piece_on(to) == EMPTY);
-          assert(square_rank(to) == RANK_5);
-          mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
-        }
-      }
+      // Generate captures of the checking piece
 
-      // Knight moves
-      b1 = pos.knights(us) & ~pinned;
-      while(b1) {
-        from = pop_1st_bit(&b1);
-        b2 = pos.knight_attacks(from) & blockSquares;
-        while(b2) {
-          to = pop_1st_bit(&b2);
-          mlist[n++].move = make_move(from, to);
-        }
-      }
-      
-      // Bishop moves
-      b1 = pos.bishops(us) & ~pinned;
-      while(b1) {
-        from = pop_1st_bit(&b1);
-        b2 = pos.bishop_attacks(from) & blockSquares;
-        while(b2) {
-          to = pop_1st_bit(&b2);
-          mlist[n++].move = make_move(from, to);
-        }
-      }
-      
-      // Rook moves
-      b1 = pos.rooks(us) & ~pinned;
-      while(b1) {
-        from = pop_1st_bit(&b1);
-        b2 = pos.rook_attacks(from) & blockSquares;
-        while(b2) {
-          to = pop_1st_bit(&b2);
-          mlist[n++].move = make_move(from, to);
-        }
+      // Pawn captures
+      b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & not_pinned;
+      while (b1)
+      {
+          from = pop_1st_bit(&b1);
+          if (relative_rank(us, checksq) == RANK_8)
+          {
+              mlist[n++].move = make_promotion_move(from, checksq, QUEEN);
+              mlist[n++].move = make_promotion_move(from, checksq, ROOK);
+              mlist[n++].move = make_promotion_move(from, checksq, BISHOP);
+              mlist[n++].move = make_promotion_move(from, checksq, KNIGHT);
+          } else
+              mlist[n++].move = make_move(from, checksq);
       }
-      
-      // Queen moves
-      b1 = pos.queens(us) & ~pinned;
-      while(b1) {
-        from = pop_1st_bit(&b1);
-        b2 = pos.queen_attacks(from) & blockSquares;
-        while(b2) {
-          to = pop_1st_bit(&b2);
-          mlist[n++].move = make_move(from, to);
-        }
+
+      // Pieces captures
+      b1 = (  (pos.piece_attacks<KNIGHT>(checksq) & pos.knights(us))
+            | (pos.piece_attacks<BISHOP>(checksq) & pos.bishops_and_queens(us))
+            | (pos.piece_attacks<ROOK>(checksq)   & pos.rooks_and_queens(us)) ) & not_pinned;
+
+      while (b1)
+      {
+          from = pop_1st_bit(&b1);
+          mlist[n++].move = make_move(from, checksq);
       }
+
+      // Blocking check evasions are possible only if the checking piece is
+      // a slider
+      if (checkers & pos.sliders())
+      {
+          Bitboard blockSquares = squares_between(checksq, ksq);
+
+          assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
+
+          // Pawn moves. Because a blocking evasion can never be a capture, we
+          // only generate pawn pushes.
+          if (us == WHITE)
+              n += generate_pawn_blocking_evasions<WHITE>(pos, not_pinned, blockSquares, mlist+n);
+          else
+              n += generate_pawn_blocking_evasions<BLACK>(pos, not_pinned, blockSquares, mlist+n);
+
+          // Pieces moves
+          b1 = pos.knights(us) & not_pinned;
+          if (b1)
+              n += generate_piece_blocking_evasions<KNIGHT>(pos, b1, blockSquares, mlist+n);
+
+          b1 = pos.bishops(us) & not_pinned;
+          if (b1)
+              n += generate_piece_blocking_evasions<BISHOP>(pos, b1, blockSquares, mlist+n);
+
+          b1 = pos.rooks(us) & not_pinned;
+          if (b1)
+              n += generate_piece_blocking_evasions<ROOK>(pos, b1, blockSquares, mlist+n);
+
+          b1 = pos.queens(us) & not_pinned;
+          if (b1)
+              n += generate_piece_blocking_evasions<QUEEN>(pos, b1, blockSquares, mlist+n);
     }
 
-    // Finally, the ugly special case of en passant captures.  An en passant
+    // Finally, the ugly 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,
+    // 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.pawns(them))) {
-      to = pos.ep_square();
-      b1 = pos.pawn_attacks(them, to) & pos.pawns(us);
-      assert(b1 != EmptyBoardBB);
-      b1 &= ~pinned;
-      while(b1) {
-        from = pop_1st_bit(&b1);
-
-        // Before generating the move, we have to make sure it is legal.
-        // This is somewhat tricky, because the two disappearing pawns may
-        // cause new "discovered checks".  We test this by removing the
-        // two relevant bits from the occupied squares bitboard, and using
-        // the low-level bitboard functions for bishop and rook attacks.
-        b2 = pos.occupied_squares();
-        clear_bit(&b2, from);
-        clear_bit(&b2, checksq);
-        if(((bishop_attacks_bb(ksq, b2) & pos.bishops_and_queens(them))
-            == EmptyBoardBB) &&
-           ((rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them))
-            == EmptyBoardBB))
-          mlist[n++].move = make_ep_move(from, to);
-      }
+    if (pos.ep_square() != SQ_NONE && (checkers & pos.pawns(them)))
+    {
+        to = pos.ep_square();
+        b1 = pos.pawn_attacks(them, to) & pos.pawns(us);
+
+        assert(b1 != EmptyBoardBB);
+
+        b1 &= not_pinned;
+        while (b1)
+        {
+            from = pop_1st_bit(&b1);
+
+            // Before generating the move, we have to make sure it is legal.
+            // This is somewhat tricky, because the two disappearing pawns may
+            // cause new "discovered checks".  We test this by removing the
+            // two relevant bits from the occupied squares bitboard, and using
+            // the low-level bitboard functions for bishop and rook attacks.
+            b2 = pos.occupied_squares();
+            clear_bit(&b2, from);
+            clear_bit(&b2, checksq);
+            if (!(  (bishop_attacks_bb(ksq, b2) & pos.bishops_and_queens(them))
+                  ||(rook_attacks_bb(ksq, b2)   & pos.rooks_and_queens(them))))
+
+                 mlist[n++].move = make_ep_move(from, to);
+        }
     }
   }
-
   return n;
 }
 
@@ -449,7 +395,7 @@ int generate_legal_moves(const Position& pos, MoveStack* mlist) {
 /// returned.  If not, the function returns MOVE_NONE.  This function must
 /// only be used when the side to move is not in check.
 
-Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) {
+Move generate_move_if_legal(const Position& pos, Move m, Bitboard pinned) {
 
   assert(pos.is_ok());
   assert(!pos.is_check());
@@ -559,7 +505,7 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) {
 
   // Proceed according to the type of the moving piece.
   if (type_of_piece(pc) == PAWN)
-  {  
+  {
       // If the destination square is on the 8/1th rank, the move must
       // be a promotion.
       if (   (  (square_rank(to) == RANK_8 && us == WHITE)
@@ -624,66 +570,123 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) {
 
 namespace {
 
-  int generate_pawn_captures(const PawnOffsets& ofs, const Position& pos, MoveStack* mlist) {
+  template<PieceType Piece>
+  int generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
+
+    Square from, to;
+    Bitboard b;
+    int n = 0;
+
+    for (int i = 0; i < pos.piece_count(us, Piece); i++)
+    {
+        from = pos.piece_list(us, Piece, i);
+        b = pos.piece_attacks<Piece>(from) & target;
+        while (b)
+        {
+            to = pop_1st_bit(&b);
+            mlist[n++].move = make_move(from, to);
+        }
+    }
+    return n;
+  }
+
+  template<>
+  int generate_piece_moves<KING>(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
+
+    Bitboard b;
+    Square to, from = pos.king_square(us);
+    int n = 0;
+
+    b = pos.piece_attacks<KING>(from) & target;
+    while (b)
+    {
+        to = pop_1st_bit(&b);
+        mlist[n++].move = make_move(from, to);
+    }
+    return n;
+  }
+
+  template<PieceType Piece>
+  int generate_piece_blocking_evasions(const Position& pos, Bitboard b,
+                                       Bitboard blockSquares, MoveStack* mlist) {
+    int n = 0;
+    while (b)
+    {
+        Square from = pop_1st_bit(&b);
+        Bitboard bb = pos.piece_attacks<Piece>(from) & blockSquares;
+        while (bb)
+        {
+            Square to = pop_1st_bit(&bb);
+            mlist[n++].move = make_move(from, to);
+        }
+    }
+    return n;
+  }
+
 
-    Bitboard pawns = pos.pawns(ofs.us);
-    Bitboard enemyPieces = pos.pieces_of_color(ofs.them);
+  template<Color Us, Color Them, Bitboard TRank8BB, SquareDelta TDELTA_NE,
+           SquareDelta TDELTA_NW, SquareDelta TDELTA_N
+          >
+  int do_generate_pawn_captures(const Position& pos, MoveStack* mlist) {    
+
+    Bitboard pawns = pos.pawns(Us);
+    Bitboard enemyPieces = pos.pieces_of_color(Them);
     Square sq;
     int n = 0;
 
     // Captures in the a1-h8 (a8-h1 for black) direction
-    Bitboard b1 = (ofs.forward_right)(pawns) & ~FileABB & enemyPieces;
+    Bitboard b1 = (Us == WHITE ? pawns << 9 : pawns >> 7) & ~FileABB & enemyPieces;
 
     // Capturing promotions
-    Bitboard b2 = b1 & ofs.Rank8BB;
+    Bitboard b2 = b1 & TRank8BB;
     while (b2)
     {
         sq = pop_1st_bit(&b2);
-        mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, QUEEN);
+        mlist[n++].move = make_promotion_move(sq - TDELTA_NE, sq, QUEEN);
     }
 
     // Capturing non-promotions
-    b2 = b1 & ~ofs.Rank8BB;
+    b2 = b1 & ~TRank8BB;
     while (b2)
     {
         sq = pop_1st_bit(&b2);
-        mlist[n++].move = make_move(sq - ofs.DELTA_NE, sq);
+        mlist[n++].move = make_move(sq - TDELTA_NE, sq);
     }
 
     // Captures in the h1-a8 (h8-a1 for black) direction
-    b1 = (ofs.forward_left)(pawns) & ~FileHBB & enemyPieces;
+    b1 = (Us == WHITE ? pawns << 7 : pawns >> 9) & ~FileHBB & enemyPieces;
 
     // Capturing promotions
-    b2 = b1 & ofs.Rank8BB;
+    b2 = b1 & TRank8BB;
     while (b2)
     {
         sq = pop_1st_bit(&b2);
-        mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, QUEEN);
+        mlist[n++].move = make_promotion_move(sq - TDELTA_NW, sq, QUEEN);
     }
 
     // Capturing non-promotions
-    b2 = b1 & ~ofs.Rank8BB;
+    b2 = b1 & ~TRank8BB;
     while (b2)
     {
         sq = pop_1st_bit(&b2);
-        mlist[n++].move = make_move(sq - ofs.DELTA_NW, sq);
+        mlist[n++].move = make_move(sq - TDELTA_NW, sq);
     }
 
     // Non-capturing promotions
-    b1 = (ofs.forward)(pawns) & pos.empty_squares() & Rank8BB;
+    b1 = (Us == WHITE ? pawns << 8 : pawns >> 8) & pos.empty_squares() & TRank8BB;
     while (b1)
     {
         sq = pop_1st_bit(&b1);
-        mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, QUEEN);
+        mlist[n++].move = make_promotion_move(sq - TDELTA_N, sq, QUEEN);
     }
 
     // En passant captures
     if (pos.ep_square() != SQ_NONE)
     {
-        assert(ofs.us != WHITE || square_rank(pos.ep_square()) == RANK_6);
-        assert(ofs.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);
 
-        b1 = pawns & pos.pawn_attacks(ofs.them, pos.ep_square());
+        b1 = pawns & pos.pawn_attacks(Them, pos.ep_square());
         assert(b1 != EmptyBoardBB);
 
         while (b1)
@@ -695,79 +698,164 @@ namespace {
     return n;
   }
 
+  template<Color Us, Color Them, Bitboard TRank8BB, Bitboard TRank3BB,
+           SquareDelta TDELTA_NE, SquareDelta TDELTA_NW, SquareDelta TDELTA_N
+          >
+  int do_generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) {   
 
-  int generate_pawn_noncaptures(const PawnOffsets& ofs, const Position& pos, MoveStack* mlist) {
-
-    Bitboard pawns = pos.pawns(ofs.us);
-    Bitboard enemyPieces = pos.pieces_of_color(ofs.them);
+    Bitboard pawns = pos.pawns(Us);
+    Bitboard enemyPieces = pos.pieces_of_color(Them);
     Bitboard emptySquares = pos.empty_squares();
     Bitboard b1, b2;
     Square sq;
     int n = 0;
 
     // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
-    b1 = ofs.forward_right(pawns) & ~FileABB & enemyPieces & ofs.Rank8BB;
+    b1 = (Us == WHITE ? pawns << 9 : pawns >> 7) & ~FileABB & enemyPieces & TRank8BB;
     while (b1)
     {
         sq = pop_1st_bit(&b1);
-        mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, ROOK);
-        mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, BISHOP);
-        mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, KNIGHT);
+        mlist[n++].move = make_promotion_move(sq - TDELTA_NE, sq, ROOK);
+        mlist[n++].move = make_promotion_move(sq - TDELTA_NE, sq, BISHOP);
+        mlist[n++].move = make_promotion_move(sq - TDELTA_NE, sq, KNIGHT);
     }
 
     // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
-    b1 = ofs.forward_left(pawns) & ~FileHBB & enemyPieces & ofs.Rank8BB;
+    b1 = (Us == WHITE ? pawns << 7 : pawns >> 9) & ~FileHBB & enemyPieces & TRank8BB;
     while (b1)
     {
         sq = pop_1st_bit(&b1);
-        mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, ROOK);
-        mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, BISHOP);
-        mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, KNIGHT);
+        mlist[n++].move = make_promotion_move(sq - TDELTA_NW, sq, ROOK);
+        mlist[n++].move = make_promotion_move(sq - TDELTA_NW, sq, BISHOP);
+        mlist[n++].move = make_promotion_move(sq - TDELTA_NW, sq, KNIGHT);
     }
 
     // Single pawn pushes
-    b1 = ofs.forward(pawns) & emptySquares;
-    b2 = b1 & ofs.Rank8BB;
+    b1 = (Us == WHITE ? pawns << 8 : pawns >> 8) & emptySquares;
+    b2 = b1 & TRank8BB;
     while (b2)
     {
       sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, ROOK);
-      mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, BISHOP);
-      mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, KNIGHT);
+      mlist[n++].move = make_promotion_move(sq - TDELTA_N, sq, ROOK);
+      mlist[n++].move = make_promotion_move(sq - TDELTA_N, sq, BISHOP);
+      mlist[n++].move = make_promotion_move(sq - TDELTA_N, sq, KNIGHT);
     }
-    b2 = b1 & ~ofs.Rank8BB;
+    b2 = b1 & ~TRank8BB;
     while (b2)
     {
         sq = pop_1st_bit(&b2);
-        mlist[n++].move = make_move(sq - ofs.DELTA_N, sq);
+        mlist[n++].move = make_move(sq - TDELTA_N, sq);
     }
 
     // Double pawn pushes
-    b2 = (ofs.forward(b1 & ofs.Rank3BB)) & emptySquares;
+    b2 = (Us == WHITE ? (b1 & TRank3BB) << 8 : (b1 & TRank3BB) >> 8) & emptySquares;
     while (b2)
     {
       sq = pop_1st_bit(&b2);
-      mlist[n++].move = make_move(sq - ofs.DELTA_N - ofs.DELTA_N, sq);
+      mlist[n++].move = make_move(sq - TDELTA_N - TDELTA_N, sq);
     }
     return n;
   }
 
 
-  int generate_piece_moves(PieceType piece, const Position &pos, MoveStack *mlist, 
-                           Color side, Bitboard target) {
+  template<Color Us, Color Them, Bitboard TRank8BB, Bitboard TRank3BB, SquareDelta TDELTA_N>
+  int do_generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist)
+  {
+    // 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.
+    int n = 0;
+    Bitboard empty = pos.empty_squares();
 
-    const Piece_attacks_fn mem_fn = piece_attacks_fn[piece];
-    Square from, to;
-    Bitboard b;
+    // Find all friendly pawns not on the enemy king's file
+    Bitboard b1 = pos.pawns(Us) & ~file_bb(ksq), b2, b3;
+
+    // Discovered checks, single pawn pushes
+    b2 = b3 = (Us == WHITE ? (b1 & dc) << 8 : (b1 & dc) >> 8) & ~TRank8BB & empty;
+    while (b3)
+    {
+        Square to = pop_1st_bit(&b3);
+        mlist[n++].move = make_move(to - TDELTA_N, to);
+    }
+
+    // Discovered checks, double pawn pushes
+    b3 = (Us == WHITE ? (b2 & TRank3BB) << 8 : (b2 & TRank3BB) >> 8) & empty;
+    while (b3)
+    {
+        Square to = pop_1st_bit(&b3);
+        mlist[n++].move = make_move(to - TDELTA_N - TDELTA_N, to);
+    }
+
+    // Direct checks. These are possible only for pawns on neighboring files
+    // of the enemy king
+
+    b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
+
+    // Direct checks, single pawn pushes
+    b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & empty;
+    b3 = b2 & pos.pawn_attacks(Them, ksq);
+    while (b3)
+    {
+        Square to = pop_1st_bit(&b3);
+        mlist[n++].move = make_move(to - TDELTA_N, to);
+    }
+
+    // Direct checks, double pawn pushes
+    b3 =  (Us == WHITE ? (b2 & TRank3BB) << 8 : (b2 & TRank3BB) >> 8)
+        & empty
+        & pos.pawn_attacks(Them, ksq);
+
+    while (b3)
+    {
+        Square to = pop_1st_bit(&b3);
+        mlist[n++].move = make_move(to - TDELTA_N - TDELTA_N, to);
+    }
+    return n;
+  }
+
+  template<PieceType Piece>
+  int generate_piece_checks(const Position& pos, Bitboard target, Bitboard dc,
+                            Square ksq, MoveStack* mlist) {
+    // Discovered checks
     int n = 0;
+    Bitboard b = target & dc;
+    while (b)
+    {
+        Square from = pop_1st_bit(&b);
+        Bitboard bb = pos.piece_attacks<Piece>(from) & pos.empty_squares();
+        while (bb)
+        {
+            Square to = pop_1st_bit(&bb);
+            mlist[n++].move = make_move(from, to);
+        }
+    }
+    // Direct checks
+    b = target & ~dc;
+    Bitboard checkSqs = pos.piece_attacks<Piece>(ksq) & pos.empty_squares();
+    while (b)
+    {
+        Square from = pop_1st_bit(&b);
+        Bitboard bb = pos.piece_attacks<Piece>(from) & checkSqs;
+        while (bb)
+        {
+            Square to = pop_1st_bit(&bb);
+            mlist[n++].move = make_move(from, to);
+        }
+    }
+    return n;
+  }
 
-    for (int i = 0; i < pos.piece_count(side, piece); i++)
+  int generate_piece_checks_king(const Position& pos, Square from, Bitboard dc,
+                                 Square ksq, MoveStack* mlist) {
+    int n = 0;
+    if (bit_is_set(dc, from))
     {
-        from = pos.piece_list(side, piece, i);
-        b = (pos.*mem_fn)(from) & target;
+        Bitboard b =   pos.piece_attacks<KING>(from)
+                     & pos.empty_squares()
+                     & ~QueenPseudoAttacks[ksq];
         while (b)
         {
-            to = pop_1st_bit(&b);
+            Square to = pop_1st_bit(&b);
             mlist[n++].move = make_move(from, to);
         }
     }
@@ -775,14 +863,58 @@ namespace {
   }
 
 
-  int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) {
+  template<Color Us, Bitboard TRANK_8, Bitboard TRank3BB, SquareDelta TDELTA_N>
+  int do_generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned,
+                                         Bitboard blockSquares, MoveStack* mlist) {
+    // Find non-pinned pawns
+    int n = 0;
+    Bitboard b1 = pos.pawns(Us) & not_pinned;
+
+    // Single pawn pushes. We don't have to AND with empty squares here,
+    // because the blocking squares will always be empty.
+    Bitboard b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & blockSquares;
+    while (b2)
+    {
+        Square to = pop_1st_bit(&b2);
+
+        assert(pos.piece_on(to) == EMPTY);
+
+        if (square_rank(to) == TRANK_8)
+        {
+            mlist[n++].move = make_promotion_move(to - TDELTA_N, to, QUEEN);
+            mlist[n++].move = make_promotion_move(to - TDELTA_N, to, ROOK);
+            mlist[n++].move = make_promotion_move(to - TDELTA_N, to, BISHOP);
+            mlist[n++].move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
+        } else
+            mlist[n++].move = make_move(to - TDELTA_N, to);
+    }
+
+    // Double pawn pushes
+    b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & pos.empty_squares() & TRank3BB;
+    b2 = (Us == WHITE ? b2 << 8 : b2 >> 8) & blockSquares;;
+    while (b2)
+    {
+        Square to = pop_1st_bit(&b2);
+
+        assert(pos.piece_on(to) == EMPTY);
+        assert(Us != WHITE || square_rank(to) == RANK_4);
+        assert(Us != BLACK || square_rank(to) == RANK_5);
+
+        mlist[n++].move = make_move(to - TDELTA_N - TDELTA_N, to);
+    }
+    return n;
+  }
+
+
+  int generate_castle_moves(const Position& pos, MoveStack* mlist) {
 
     int n = 0;
+    Color us = pos.side_to_move();
 
     if (pos.can_castle(us))
     {
         Color them = opposite_color(us);
-        Square ksq = pos.king_square(us);        
+        Square ksq = pos.king_square(us);
 
         assert(pos.piece_on(ksq) == king_of_color(us));
 
@@ -815,7 +947,7 @@ namespace {
           Square c1 = relative_square(us, SQ_C1);
           Square d1 = relative_square(us, SQ_D1);
           Square s;
-          bool illegal = false;        
+          bool illegal = false;
 
           assert(pos.piece_on(rsq) == rook_of_color(us));
 
@@ -832,95 +964,11 @@ namespace {
             && (   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);
-        }
-    }
-
-    // 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();
-
-    // Find all friendly pawns not on the enemy king's file
-    Bitboard b1 = pos.pawns(pos.side_to_move()) & ~file_bb(ksq), b2, b3;
-
-    // Discovered checks, single pawn pushes
-    b2 = b3 = (ofs.forward)(b1 & dc) & ~ofs.Rank8BB & empty;
-    while (b3)
-    {
-        Square to = pop_1st_bit(&b3);
-        mlist[n++].move = make_move(to - ofs.DELTA_N, to);
-    }
-
-    // Discovered checks, double pawn pushes
-    b3 = (ofs.forward)(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);
-    }
-
-    // Direct checks. These are possible only for pawns on neighboring files
-    // of the enemy king
-
-    b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
-
-    // Direct checks, single pawn pushes
-    b2 = (ofs.forward)(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.forward)(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;
-  }
 }