Use a flag in TT to track null search values

[stockfish] / src / move.h

diff --git a/src/move.h b/src/move.h
index 672eade6bcb676f4f9751070d2bcbab86f88965d..0eb7b18b4cc97d8653bba9517d2db40dd7727d5d 100644 (file)
--- a/src/move.h
+++ b/src/move.h
@@ -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
@@ -62,9 +62,83 @@ struct MoveStack {
   int score;
 };
 
-// Note that operator< is set up such that std::sort() will sort in descending order
+// Note that operator< is set up such that sorting will be in descending order
 inline bool operator<(const MoveStack& f, const MoveStack& s) { return s.score < f.score; }
 
+// An helper insertion sort implementation
+template<typename T>
+inline void insertion_sort(T* firstMove, T* lastMove)
+{
+    T value;
+    T *cur, *p, *d;
+
+    if (firstMove != lastMove)
+        for (cur = firstMove + 1; cur != lastMove; cur++)
+        {
+            p = d = cur;
+            value = *p--;
+            if (value < *p)
+            {
+                do *d = *p;
+                while (--d != firstMove && value < *--p);
+                *d = value;
+            }
+        }
+}
+
+// Our dedicated sort in range [firstMove, lastMove), first splits
+// positive scores from ramining then order seaprately the two sets.
+template<typename T>
+inline void sort_moves(T* firstMove, T* lastMove, T** lastPositive)
+{
+    T tmp;
+    T *p, *d;
+
+    d = lastMove;
+    p = firstMove - 1;
+
+    d->score = -1; // right guard
+
+    // Split positives vs non-positives
+    do {
+        while ((++p)->score > 0);
+
+        if (p != d)
+        {
+            while (--d != p && d->score <= 0);
+
+            tmp = *p;
+            *p = *d;
+            *d = tmp;
+        }
+
+    } while (p != d);
+
+    // Sort just positive scored moves, remaining only when we get there
+    insertion_sort<T>(firstMove, p);
+    *lastPositive = p;
+}
+
+// Picks up the best move in range [curMove, lastMove), one per cycle.
+// It is faster then sorting all the moves in advance when moves are few,
+// as normally are the possible captures. Note that is not a stable alghoritm.
+template<typename T>
+inline T pick_best(T* curMove, T* lastMove)
+{
+    T bestMove, tmp;
+
+    bestMove = *curMove;
+    while (++curMove != lastMove)
+    {
+        if (*curMove < bestMove)
+        {
+            tmp = *curMove;
+            *curMove = bestMove;
+            bestMove = tmp;
+        }
+    }
+    return bestMove;
+}
 
 ////
 //// Inline functions
@@ -82,6 +156,10 @@ inline PieceType move_promotion_piece(Move m) {
   return PieceType((int(m) >> 12) & 7);
 }
 
+inline int move_is_special(Move m) {
+  return m & (0x1F << 12);
+}
+
 inline int move_is_promotion(Move m) {
   return m & (7 << 12);
 }