Add "Best Book Move" UCI option

[stockfish] / src / book.cpp

diff --git a/src/book.cpp b/src/book.cpp
index 0c72d8e80d862d35b9f17aafc5d3f14cf7321a4c..dbd037885711c191b23d53622a6b6aa8db75dba9 100644 (file)
--- a/src/book.cpp
+++ b/src/book.cpp
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2009 Marco Costalba
+  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -390,7 +390,7 @@ void Book::close() {
 /// Book::file_name() returns the file name of the currently active book,
 /// or the empty string if no book is open.
 
-const string Book::file_name() const {
+const string Book::file_name() { // Not const to compile on HP-UX 11.X
 
   return is_open() ? fileName : "";
 }
@@ -399,14 +399,15 @@ const string Book::file_name() const {
 /// Book::get_move() gets a book move for a given position. Returns
 /// MOVE_NONE if no book move is found.
 
-Move Book::get_move(const Position& pos) {
+Move Book::get_move(const Position& pos, bool findBestMove) {
 
   if (!is_open() || bookSize == 0)
       return MOVE_NONE;
 
-  int bookMove = 0, scoresSum = 0;
-  uint64_t key = book_key(pos);
   BookEntry entry;
+  int bookMove = MOVE_NONE;
+  int scoresSum = 0, bestScore = 0;
+  uint64_t key = book_key(pos);
 
   // Choose a book move among the possible moves for the given position
   for (int idx = find_key(key); idx < bookSize; idx++)
@@ -419,6 +420,17 @@ Move Book::get_move(const Position& pos) {
 
       assert(score > 0);
 
+      // If findBestMove is true choose highest rated book move
+      if (findBestMove)
+      {
+          if (score > bestScore)
+          {
+              bestScore = score;
+              bookMove = entry.move;
+          }
+          continue;
+      }
+
       // Choose book move according to its score. If a move has a very
       // high score it has more probability to be choosen then a one with
       // lower score. Note that first entry is always chosen.
@@ -430,7 +442,7 @@ Move Book::get_move(const Position& pos) {
       return MOVE_NONE;
 
   MoveStack mlist[256];
-  MoveStack* last = generate_legal_moves(pos, mlist);
+  MoveStack* last = generate_moves(pos, mlist);
   for (MoveStack* cur = mlist; cur != last; cur++)
       if ((int(cur->move) & 07777) == bookMove)
           return cur->move;