Revert _BitScanForward64 support

[stockfish] / src / movegen.cpp

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 440dd83985f8b5902db5f30f53af8f65037047f3..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,
@@ -53,7 +54,7 @@ namespace {
   template<CastlingSide Side>
   MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist);
 
-  template<Color Us, Rank, Bitboard, SquareDelta>
+  template<Color Us>
   MoveStack* generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*);
 
   template<Color Us>
@@ -65,7 +66,7 @@ namespace {
   template<Color Us>
   MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist);
 
-  template<Color, Color, Bitboard, Bitboard, SquareDelta>
+  template<Color Us>
   MoveStack* generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*);
 
   template<Color Us, SquareDelta Direction>
@@ -88,11 +89,8 @@ namespace {
   template<>
   inline MoveStack* generate_piece_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
 
-    if (us == WHITE)
-        return generate_pawn_checks<WHITE, BLACK, Rank8BB, Rank3BB, DELTA_N>(p, dc, ksq, m);
-    else
-        return generate_pawn_checks<BLACK, WHITE, Rank1BB, Rank6BB, DELTA_S>(p, dc, ksq, m);
-
+    return (us == WHITE ? generate_pawn_checks<WHITE>(p, dc, ksq, m)
+                        : generate_pawn_checks<BLACK>(p, dc, ksq, m));
   }
 
   // Template generate_piece_moves() with specializations and overloads
@@ -121,10 +119,9 @@ namespace {
   template<>
   inline MoveStack* generate_piece_moves<PAWN>(const Position& p, MoveStack* m,
                                                Color us, Bitboard t, Bitboard pnd) {
-    if (us == WHITE)
-        return generate_pawn_blocking_evasions<WHITE, RANK_8, Rank3BB, DELTA_N>(p, pnd, t, m);
-    else
-        return generate_pawn_blocking_evasions<BLACK, RANK_1, Rank6BB, DELTA_S>(p, pnd, t, m);
+
+    return (us == WHITE ? generate_pawn_blocking_evasions<WHITE>(p, pnd, t, m)
+                        : generate_pawn_blocking_evasions<BLACK>(p, pnd, t, m));
   }
 }
 
@@ -752,18 +749,27 @@ namespace {
   }
 
 
-  template<Color Us, Color Them, Bitboard TRank8BB, Bitboard TRank3BB, SquareDelta TDELTA_N>
+  template<Color Us>
   MoveStack* generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist)
   {
+    // Calculate our parametrized parameters at compile time
+    const Color Them = (Us == WHITE ? BLACK : WHITE);
+    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 != EmptyBoardBB)
+    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.
-        b1 = pos.pawns(Us) & ~file_bb(ksq);
+        b1 = pawns & ~file_bb(ksq);
 
         // Discovered checks, single pawn pushes, no promotions
         b2 = b3 = move_pawns<Us, DELTA_N>(b1 & dc) & empty & ~TRank8BB;
@@ -783,10 +789,15 @@ namespace {
     }
 
     // Direct checks. These are possible only for pawns on neighboring files
-    // of the enemy king.
-    b1 = pos.pawns(Us) & neighboring_files_bb(ksq) & ~dc;
+    // 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)
@@ -825,30 +836,36 @@ 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;
   }
 
-  template<Color Us, Rank TRANK_8, Bitboard TRank3BB, SquareDelta TDELTA_N>
+  template<Color Us>
   MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard pinned,
                                              Bitboard blockSquares, MoveStack* mlist) {
+
+    // Calculate our parametrized parameters at compile time
+    const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
+    const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
+    const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+
     Square to;
 
     // Find non-pinned pawns and push them one square
@@ -863,7 +880,7 @@ namespace {
 
         assert(pos.piece_on(to) == EMPTY);
 
-        if (square_rank(to) == TRANK_8)
+        if (square_rank(to) == TRank8BB)
         {
             (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
             (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);