Simplify castlingPath (#2088)

[stockfish] / src / endgame.cpp

diff --git a/src/endgame.cpp b/src/endgame.cpp
index 66ee54d846044c90d03ec4dcaf9699e07aae13ee..efc41a98844799be346293c83e103da236b32a48 100644 (file)
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cassert>
 
 #include "bitboard.h"
@@ -77,10 +76,7 @@ namespace {
     if (file_of(pos.square<PAWN>(strongSide)) >= FILE_E)
         sq = Square(sq ^ 7); // Mirror SQ_H1 -> SQ_A1
 
-    if (strongSide == BLACK)
-        sq = ~sq;
-
-    return sq;
+    return strongSide == WHITE ? sq : ~sq;
   }
 
 } // namespace
@@ -131,7 +127,7 @@ 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
@@ -286,6 +282,21 @@ Value Endgame<KQKR>::operator()(const Position& pos) const {
 }
 
 
+/// KNN vs KP. Simply push the opposing king to the corner
+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)];
+
+  return strongSide == pos.side_to_move() ? result : -result;
+}
+
+
 /// Some cases of trivial draws
 template<> Value Endgame<KNNK>::operator()(const Position&) const { return VALUE_DRAW; }
 
@@ -724,6 +735,9 @@ ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
 template<>
 ScaleFactor Endgame<KNPKB>::operator()(const Position& pos) const {
 
+  assert(verify_material(pos, strongSide, KnightValueMg, 1));
+  assert(verify_material(pos, weakSide, BishopValueMg, 0));
+
   Square pawnSq = pos.square<PAWN>(strongSide);
   Square bishopSq = pos.square<BISHOP>(weakSide);
   Square weakKingSq = pos.square<KING>(weakSide);