X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=1a8c7e00d6a0bc24af2e44c395a70fb9eb6c1d4b;hp=a51383f0d4eed8c2c9c08d318a6f422c743102a1;hb=d3608c4e79a29110f4c4a369d7207c6dd8e01f34;hpb=ea4e22be1da1ccbf316d27f2eb3b14d0e13388e4

diff --git a/src/position.cpp b/src/position.cpp
index a51383f0..1a8c7e00 100644
--- a/src/position.cpp
+++ b/src/position.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) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2013 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
@@ -19,6 +19,7 @@
 
 #include <cassert>
 #include <cstring>
+#include <iomanip>
 #include <iostream>
 #include <sstream>
 #include <algorithm>
@@ -400,14 +401,15 @@ const string Position::pretty(Move move) const {
       if (piece_on(sq) != NO_PIECE)
           brd[513 - 68*rank_of(sq) + 4*file_of(sq)] = PieceToChar[piece_on(sq)];
 
-  ss << brd << "\nFen: " << fen() << "\nKey: " << st->key << "\nCheckers: ";
+  ss << brd << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase
+     << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: ";
 
   for (Bitboard b = checkers(); b; )
       ss << square_to_string(pop_lsb(&b)) << " ";
 
   ss << "\nLegal moves: ";
-  for (MoveList<LEGAL> ml(*this); !ml.end(); ++ml)
-      ss << move_to_san(*const_cast<Position*>(this), ml.move()) << " ";
+  for (MoveList<LEGAL> it(*this); *it; ++it)
+      ss << move_to_san(*const_cast<Position*>(this), *it) << " ";
 
   return ss.str();
 }
@@ -1127,10 +1129,10 @@ void Position::undo_null_move() {
 
 
 /// Position::see() is a static exchange evaluator: It tries to estimate the
-/// material gain or loss resulting from a move. There are three versions of
-/// this function: One which takes a destination square as input, one takes a
-/// move, and one which takes a 'from' and a 'to' square. The function does
-/// not yet understand promotions captures.
+/// material gain or loss resulting from a move. Parameter 'asymmThreshold' takes
+/// tempi into account. If the side who initiated the capturing sequence does the
+/// last capture, he loses a tempo and if the result is below 'asymmThreshold'
+/// the capturing sequence is considered bad.
 
 int Position::see_sign(Move m) const {
 
@@ -1145,7 +1147,7 @@ int Position::see_sign(Move m) const {
   return see(m);
 }
 
-int Position::see(Move m) const {
+int Position::see(Move m, int asymmThreshold) const {
 
   Square from, to;
   Bitboard occupied, attackers, stmAttackers;
@@ -1222,6 +1224,15 @@ int Position::see(Move m) const {
 
   } while (stmAttackers);
 
+  // If we are doing asymmetric SEE evaluation and the same side does the first
+  // and the last capture, he loses a tempo and gain must be at least worth
+  // 'asymmThreshold', otherwise we replace the score with a very low value,
+  // before negamaxing.
+  if (asymmThreshold)
+      for (int i = 0; i < slIndex; i += 2)
+          if (swapList[i] < asymmThreshold)
+              swapList[i] = - QueenValueMg * 16;
+
   // Having built the swap list, we negamax through it to find the best
   // achievable score from the point of view of the side to move.
   while (--slIndex)
@@ -1365,7 +1376,6 @@ Value Position::compute_non_pawn_material(Color c) const {
 /// Position::is_draw() tests whether the position is drawn by material,
 /// repetition, or the 50 moves rule. It does not detect stalemates, this
 /// must be done by the search.
-template<bool SkipRepetition>
 bool Position::is_draw() const {
 
   // Draw by material?
@@ -1378,33 +1388,26 @@ bool Position::is_draw() const {
       return true;
 
   // Draw by repetition?
-  if (!SkipRepetition)
-  {
-      int i = 4, e = std::min(st->rule50, st->pliesFromNull);
+  int i = 4, e = std::min(st->rule50, st->pliesFromNull);
 
-      if (i <= e)
-      {
-          StateInfo* stp = st->previous->previous;
+  if (i <= e)
+  {
+      StateInfo* stp = st->previous->previous;
 
-          do {
-              stp = stp->previous->previous;
+      do {
+          stp = stp->previous->previous;
 
-              if (stp->key == st->key)
-                  return true;
+          if (stp->key == st->key)
+              return true;
 
-              i += 2;
+          i += 2;
 
-          } while (i <= e);
-      }
+      } while (i <= e);
   }
 
   return false;
 }
 
-// Explicit template instantiations
-template bool Position::is_draw<false>() const;
-template bool Position::is_draw<true>() const;
-
 
 /// Position::flip() flips position with the white and black sides reversed. This
 /// is only useful for debugging especially for finding evaluation symmetry bugs.