X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=74e16fa6941b0e5e6196c4b319cbd122d6fa5940;hp=e10f8d5da975646d236468f6dc251f0052df60bb;hb=09f53dbfa5b55e761ca8070960345ab140baad04;hpb=8cfe27b76521f3c357b8d3542717aceaa5eee23b

diff --git a/src/endgame.cpp b/src/endgame.cpp
index e10f8d5d..74e16fa6 100644
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -2,7 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, 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
@@ -74,7 +74,7 @@ namespace {
     assert(pos.count<PAWN>(strongSide) == 1);
 
     if (file_of(pos.square<PAWN>(strongSide)) >= FILE_E)
-        sq = Square(sq ^ 7); // Mirror SQ_H1 -> SQ_A1
+        sq = Square(int(sq) ^ 7); // Mirror SQ_H1 -> SQ_A1
 
     return strongSide == WHITE ? sq : ~sq;
   }
@@ -137,7 +137,7 @@ Value Endgame<KXK>::operator()(const Position& pos) const {
       ||(pos.count<BISHOP>(strongSide) && pos.count<KNIGHT>(strongSide))
       || (   (pos.pieces(strongSide, BISHOP) & ~DarkSquares)
           && (pos.pieces(strongSide, BISHOP) &  DarkSquares)))
-      result = std::min(result + VALUE_KNOWN_WIN, VALUE_MATE_IN_MAX_PLY - 1);
+      result = std::min(result + VALUE_KNOWN_WIN, VALUE_TB_WIN_IN_MAX_PLY - 1);
 
   return strongSide == pos.side_to_move() ? result : -result;
 }
@@ -155,19 +155,19 @@ Value Endgame<KBNK>::operator()(const Position& pos) const {
   Square loserKSq = pos.square<KING>(weakSide);
   Square bishopSq = pos.square<BISHOP>(strongSide);
 
-  // If our Bishop does not attack A1/H8, we flip the enemy king square
+  // If our bishop does not attack A1/H8, we flip the enemy king square
   // to drive to opposite corners (A8/H1).
 
   Value result =  VALUE_KNOWN_WIN
                 + PushClose[distance(winnerKSq, loserKSq)]
                 + PushToCorners[opposite_colors(bishopSq, SQ_A1) ? ~loserKSq : loserKSq];
 
-  assert(abs(result) < VALUE_MATE_IN_MAX_PLY);
+  assert(abs(result) < VALUE_TB_WIN_IN_MAX_PLY);
   return strongSide == pos.side_to_move() ? result : -result;
 }
 
 
-/// KP vs K. This endgame is evaluated with the help of a bitbase.
+/// KP vs K. This endgame is evaluated with the help of a bitbase
 template<>
 Value Endgame<KPK>::operator()(const Position& pos) const {
 
@@ -310,16 +310,17 @@ Value Endgame<KQKR>::operator()(const Position& pos) const {
 }
 
 
-/// KNN vs KP. Simply push the opposing king to the corner
+/// KNN vs KP. Very drawish, but there are some mate opportunities if we can
+//  press the weakSide King to a corner before the pawn advances too much.
 template<>
 Value Endgame<KNNKP>::operator()(const Position& pos) const {
 
   assert(verify_material(pos, strongSide, 2 * KnightValueMg, 0));
   assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
 
-  Value result =  2 * KnightValueEg
-                - PawnValueEg
-                + PushToEdges[pos.square<KING>(weakSide)];
+  Value result =      PawnValueEg
+               +  2 * PushToEdges[pos.square<KING>(weakSide)]
+               - 10 * relative_rank(weakSide, pos.square<PAWN>(weakSide));
 
   return strongSide == pos.side_to_move() ? result : -result;
 }