simplified gives check castling

[stockfish] / src / position.cpp

diff --git a/src/position.cpp b/src/position.cpp
index e6fdb511fcc10a03f11ab3eb72fd79917f52d96e..a052cf32f03dc6d21a56f0f2b2b8dd2e59a3f6a0 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -331,8 +331,7 @@ void Position::set_check_info() const {
 
 /// Position::set_state() computes the hash keys of the position, and other
 /// data that once computed is updated incrementally as moves are made.
-/// The function is only used when a new position is set up, and to verify
-/// the correctness of the StateInfo data when running in debug mode.
+/// The function is only used when a new position is set up
 
 void Position::set_state() const {
 
@@ -639,9 +638,9 @@ bool Position::gives_check(Move m) const {
       return true;
 
   // Is there a discovered check?
-  if (   (blockers_for_king(~sideToMove) & from)
-      && !aligned(from, to, square<KING>(~sideToMove)))
-      return true;
+  if (blockers_for_king(~sideToMove) & from)
+      return   !aligned(from, to, square<KING>(~sideToMove))
+            || type_of(m) == CASTLING;
 
   switch (type_of(m))
   {
@@ -666,11 +665,9 @@ bool Position::gives_check(Move m) const {
   default: //CASTLING
   {
       // Castling is encoded as 'king captures the rook'
-      Square ksq = square<KING>(~sideToMove);
       Square rto = relative_square(sideToMove, to > from ? SQ_F1 : SQ_D1);
 
-      return   (attacks_bb<ROOK>(rto) & ksq)
-            && (attacks_bb<ROOK>(rto, pieces() ^ from ^ to) & ksq);
+      return check_squares(ROOK) & rto;
   }
   }
 }