Revert _BitScanForward64 support

[stockfish] / src / movegen.cpp

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 14705d30df86c733a0519169bae8fb171777bfb9..1135c21976f416a9bf0116f0936972dc9bde2afe 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -24,6 +24,7 @@
 
 #include <cassert>
 
+#include "bitcount.h"
 #include "movegen.h"
 
 // Simple macro to wrap a very common while loop, no facny, no flexibility,
@@ -756,13 +757,15 @@ namespace {
     const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
     const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
     const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+    const SquareDelta TDELTA_S = (Us == WHITE ? DELTA_S : DELTA_N);
 
     Bitboard b1, b2, b3;
-    Bitboard empty = pos.empty_squares();
     Bitboard pawns = pos.pawns(Us);
 
     if (dc & pawns)
     {
+         Bitboard empty = pos.empty_squares();
+
         // Pawn moves which gives discovered check. This is possible only if the
         // pawn is not on the same file as the enemy king, because we don't
         // generate captures.
@@ -786,10 +789,15 @@ namespace {
     }
 
     // Direct checks. These are possible only for pawns on neighboring files
-    // of the enemy king.
+    // and in the two ranks that, after the push, are in front of the enemy king.
     b1 = pawns & neighboring_files_bb(ksq) & ~dc;
+    b2 = rank_bb(ksq + 2 * TDELTA_S) | rank_bb(ksq + 3 * TDELTA_S);
+    b1 &= b2;
+    if (!b1)
+        return mlist;
 
     // Direct checks, single pawn pushes
+    Bitboard empty = pos.empty_squares();
     b2 = move_pawns<Us, DELTA_N>(b1) & empty;
     b3 = b2 & pos.pawn_attacks(Them, ksq);
     while (b3)
@@ -828,23 +836,23 @@ namespace {
 
     // Direct checks
     b = target & ~dc;
-    if (Piece == KING || !b)
-        return mlist;
-
-    Bitboard checkSqs = pos.piece_attacks<Piece>(ksq) & pos.empty_squares();
-    if (!checkSqs)
-        return mlist;
-
-    while (b)
+    if (Piece != KING || b)
     {
-        Square from = pop_1st_bit(&b);
-        if (   (Piece == QUEEN  && !(QueenPseudoAttacks[from]  & checkSqs))
-            || (Piece == ROOK   && !(RookPseudoAttacks[from]   & checkSqs))
-            || (Piece == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
-            continue;
+        Bitboard checkSqs = pos.piece_attacks<Piece>(ksq) & pos.empty_squares();
+        if (!checkSqs)
+            return mlist;
 
-        Bitboard bb = pos.piece_attacks<Piece>(from) & checkSqs;
-        SERIALIZE_MOVES(bb);
+        while (b)
+        {
+            Square from = pop_1st_bit(&b);
+            if (   (Piece == QUEEN  && !(QueenPseudoAttacks[from]  & checkSqs))
+                || (Piece == ROOK   && !(RookPseudoAttacks[from]   & checkSqs))
+                || (Piece == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
+                continue;
+
+            Bitboard bb = pos.piece_attacks<Piece>(from) & checkSqs;
+            SERIALIZE_MOVES(bb);
+        }
     }
     return mlist;
   }