Contempt factor: use DrawValue also in case of stealmates

[stockfish] / src / history.h

diff --git a/src/history.h b/src/history.h
index 9206cdf4bc7d8a45ad34612e12244ec23a55dcc2..7899c842ae99b54fc0b4552639631c317413b4df 100644 (file)
--- a/src/history.h
+++ b/src/history.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) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2012 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
@@ -20,13 +20,10 @@
 #if !defined(HISTORY_H_INCLUDED)
 #define HISTORY_H_INCLUDED
 
+#include <algorithm>
 #include <cstring>
 
-#include "depth.h"
-#include "move.h"
-#include "piece.h"
-#include "value.h"
-
+#include "types.h"
 
 /// The History class stores statistics about how often different moves
 /// have been successful or unsuccessful during the current search. These
@@ -38,12 +35,13 @@
 class History {
 
 public:
-  History() { clear(); }
   void clear();
-  int value(Piece p, Square to) const;
-  void update(Piece p, Square to, Value delta);
+  Value value(Piece p, Square to) const;
+  void add(Piece p, Square to, Value bonus);
   Value gain(Piece p, Square to) const;
-  void update_gain(Piece p, Square to, Value delta);
+  void update_gain(Piece p, Square to, Value g);
+
+  static const Value MaxValue = Value(2000);
 
 private:
   Value history[16][64];  // [piece][to_square]
@@ -51,28 +49,24 @@ private:
 };
 
 inline void History::clear() {
-  memset(history,  0, 16 * 64 * sizeof(int));
-  memset(maxGains, 0, 16 * 64 * sizeof(int));
+  memset(history,  0, 16 * 64 * sizeof(Value));
+  memset(maxGains, 0, 16 * 64 * sizeof(Value));
 }
 
-inline int History::value(Piece p, Square to) const {
+inline Value History::value(Piece p, Square to) const {
   return history[p][to];
 }
 
-inline void History::update(Piece p, Square to, Value bonus) {
-  history[p][to] += bonus;
+inline void History::add(Piece p, Square to, Value bonus) {
+  if (abs(history[p][to] + bonus) < MaxValue) history[p][to] += bonus;
 }
 
 inline Value History::gain(Piece p, Square to) const {
   return maxGains[p][to];
 }
 
-inline void History::update_gain(Piece p, Square to, Value gain) {
-
-  if (gain >= maxGains[p][to])
-      maxGains[p][to] = gain;
-  else
-      maxGains[p][to]--;
+inline void History::update_gain(Piece p, Square to, Value g) {
+  maxGains[p][to] = std::max(g, maxGains[p][to] - 1);
 }
 
 #endif // !defined(HISTORY_H_INCLUDED)