Grammar fix in MovePicker::next_move

[stockfish] / src / movepick.cpp

diff --git a/src/movepick.cpp b/src/movepick.cpp
index ec36edfee5b278c859552c8e4b12f6a816f57b98..f3e094c6517c67fecc4b883e08f0d414105790ee 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.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) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2014 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
@@ -50,7 +50,7 @@ namespace {
   }
 
   // Unary predicate used by std::partition to split positive scores from remaining
-  // ones so to sort separately the two sets, and with the second sort delayed.
+  // ones so as to sort the two sets separately, with the second sort delayed.
   inline bool has_positive_score(const ExtMove& ms) { return ms.score > 0; }
 
   // Picks the best move in the range (begin, end) and moves it to the front.
@@ -65,19 +65,20 @@ namespace {
 
 
 /// Constructors of the MovePicker class. As arguments we pass information
-/// to help it to return the presumably good moves first, to decide which
+/// to help it to return the (presumably) good moves first, to decide which
 /// moves to return (in the quiescence search, for instance, we only want to
-/// search captures, promotions and some checks) and about how important good
-/// move ordering is at the current node.
+/// search captures, promotions and some checks) and how important good move
+/// ordering is at the current node.
 
 MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h,
-                       Move* cm, Search::Stack* s) : pos(p), history(h), depth(d) {
+                       Move* cm, Move* fm, Search::Stack* s) : pos(p), history(h), depth(d) {
 
   assert(d > DEPTH_ZERO);
 
   cur = end = moves;
   endBadCaptures = moves + MAX_MOVES - 1;
   countermoves = cm;
+  followupmoves = fm;
   ss = s;
 
   if (p.checkers())
@@ -230,15 +231,28 @@ void MovePicker::generate_next() {
       killers[0].move = ss->killers[0];
       killers[1].move = ss->killers[1];
       killers[2].move = killers[3].move = MOVE_NONE;
+      killers[4].move = killers[5].move = MOVE_NONE;
 
       // Be sure countermoves are different from killers
       for (int i = 0; i < 2; ++i)
-          if (countermoves[i] != cur->move && countermoves[i] != (cur+1)->move)
+          if (   countermoves[i] != (cur+0)->move
+              && countermoves[i] != (cur+1)->move)
               (end++)->move = countermoves[i];
 
       if (countermoves[1] && countermoves[1] == countermoves[0]) // Due to SMP races
           killers[3].move = MOVE_NONE;
 
+      // Be sure followupmoves are different from killers and countermoves
+      for (int i = 0; i < 2; ++i)
+          if (   followupmoves[i] != (cur+0)->move
+              && followupmoves[i] != (cur+1)->move
+              && followupmoves[i] != (cur+2)->move
+              && followupmoves[i] != (cur+3)->move)
+              (end++)->move = followupmoves[i];
+
+      if (followupmoves[1] && followupmoves[1] == followupmoves[0]) // Due to SMP races
+          (--end)->move = MOVE_NONE;
+
       return;
 
   case QUIETS_1_S1:
@@ -284,9 +298,9 @@ void MovePicker::generate_next() {
 
 
 /// next_move() is the most important method of the MovePicker class. It returns
-/// a new pseudo legal move every time is called, until there are no more moves
+/// a new pseudo legal move every time it is called, until there are no more moves
 /// left. It picks the move with the biggest score from a list of generated moves
-/// taking care not returning the ttMove if has already been searched previously.
+/// taking care not to return the ttMove if it has already been searched.
 template<>
 Move MovePicker::next_move<false>() {
 
@@ -330,7 +344,9 @@ Move MovePicker::next_move<false>() {
               && move != killers[0].move
               && move != killers[1].move
               && move != killers[2].move
-              && move != killers[3].move)
+              && move != killers[3].move
+              && move != killers[4].move
+              && move != killers[5].move)
               return move;
           break;