Micro-optimize castling handling in do_move()

[stockfish] / src / move.cpp

diff --git a/src/move.cpp b/src/move.cpp
index 7504615d6d670c5ee0e7279ca90c57aa06bd6b27..0a620781ce1be0a85eb9929bbf60691b504a7f42 100644 (file)
--- a/src/move.cpp
+++ b/src/move.cpp
@@ -59,7 +59,7 @@ const string move_to_uci(Move m, bool chess960) {
       return from == SQ_E1 ? "e1c1" : "e8c8";
 
   if (move_is_promotion(m))
-      promotion = char(tolower(piece_type_to_char(move_promotion_piece(m))));
+      promotion = char(tolower(piece_type_to_char(promotion_piece_type(m))));
 
   return square_to_string(from) + square_to_string(to) + promotion;
 }
@@ -91,8 +91,9 @@ const string move_to_san(Position& pos, Move m) {
   assert(pos.is_ok());
   assert(move_is_ok(m));
 
-  MoveStack mlist[MAX_MOVES];
-  Square from = move_from(m);
+  Bitboard attackers;
+  bool ambiguousMove, ambiguousFile, ambiguousRank;
+  Square sq, from = move_from(m);
   Square to = move_to(m);
   PieceType pt = pos.type_of_piece_on(from);
   string san;
@@ -113,31 +114,30 @@ const string move_to_san(Position& pos, Move m) {
       {
           san = piece_type_to_char(pt);
 
-          // Collect all legal moves of piece type 'pt' with destination 'to'
-          MoveStack* last = generate<MV_LEGAL>(pos, mlist);
-          int f = 0, r = 0, cnt = 0;
+          // Disambiguation if we have more then one piece with destination 'to'
+          // note that for pawns is not needed because starting file is explicit.
+          attackers = pos.attackers_to(to) & pos.pieces(pt, pos.side_to_move());
+          clear_bit(&attackers, from);
+          ambiguousMove = ambiguousFile = ambiguousRank = false;
 
-          for (MoveStack* cur = mlist; cur != last; cur++)
-              if (   move_to(cur->move) == to
-                  && pos.type_of_piece_on(move_from(cur->move)) == pt)
-              {
-                  cnt++;
+          while (attackers)
+          {
+              sq = pop_1st_bit(&attackers);
 
-                  if (square_file(move_from(cur->move)) == square_file(from))
-                      f++;
+              if (square_file(sq) == square_file(from))
+                  ambiguousFile = true;
 
-                  if (square_rank(move_from(cur->move)) == square_rank(from))
-                      r++;
-              }
+              if (square_rank(sq) == square_rank(from))
+                  ambiguousRank = true;
 
-          assert(cnt > 0 && f > 0 && r > 0);
+              ambiguousMove = true;
+          }
 
-          // Disambiguation if we have more then one piece with destination 'to'
-          if (cnt > 1)
+          if (ambiguousMove)
           {
-              if (f == 1)
+              if (!ambiguousFile)
                   san += file_to_char(square_file(from));
-              else if (r == 1)
+              else if (!ambiguousRank)
                   san += rank_to_char(square_rank(from));
               else
                   san += square_to_string(from);
@@ -157,7 +157,7 @@ const string move_to_san(Position& pos, Move m) {
       if (move_is_promotion(m))
       {
           san += '=';
-          san += piece_type_to_char(move_promotion_piece(m));
+          san += piece_type_to_char(promotion_piece_type(m));
       }
   }