X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fhistory.cpp;h=6849839ca2305161b24b32e4be106de833126c2f;hp=949ba316420d8dc5351e412e32f1e23b414b261a;hb=3e38e61565c9ee6e3ff83dddfae22908bd2594b4;hpb=2161d8b0b3df48db419a25e3bc626c21eb062d75

diff --git a/src/history.cpp b/src/history.cpp
index 949ba316..6849839c 100644
--- a/src/history.cpp
+++ b/src/history.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
@@ -41,7 +41,8 @@ History::History() { clear(); }
 /// History::clear() clears the history tables
 
 void History::clear() {
-  memset(history, 0, 2 * 8 * 64 * sizeof(int));
+  memset(history, 0, 16 * 64 * sizeof(int));
+  memset(maxStaticValueDelta, 0, 16 * 64 * sizeof(int));
 }
 
 
@@ -61,7 +62,7 @@ void History::success(Piece p, Square to, Depth d) {
   if (history[p][to] >= HistoryMax)
       for (int i = 0; i < 16; i++)
           for (int j = 0; j < 64; j++)
-              history[i][j] /= 4;
+              history[i][j] /= 2;
 }
 
 
@@ -75,18 +76,23 @@ void History::failure(Piece p, Square to, Depth d) {
   assert(square_is_ok(to));
 
   history[p][to] -= int(d) * int(d);
-  if (history[p][to] < 0)
-      history[p][to] = 0;
-}
 
+  // Prevent history underflow
+  if (history[p][to] <= -HistoryMax)
+      for (int i = 0; i < 16; i++)
+          for (int j = 0; j < 64; j++)
+              history[i][j] /= 2;
+}
 
-/// History::move_ordering_score() returns an integer value used to order the
-/// non-capturing moves in the MovePicker class.
 
-int History::move_ordering_score(Piece p, Square to) const {
+/// History::set_gain() and History::gain() store and retrieve the
+/// gain of a move given the delta of the static position evaluations
+/// before and after the move.
 
-  assert(piece_is_ok(p));
-  assert(square_is_ok(to));
+void History::set_gain(Piece p, Square to, Value delta) {
 
-  return history[p][to];
+  if (delta >= maxStaticValueDelta[p][to])
+      maxStaticValueDelta[p][to] = delta;
+  else
+      maxStaticValueDelta[p][to]--;
 }