Simplify pawn captures generation

[stockfish] / src / movegen.cpp

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 0ec1fceabbf7a132fbd931d5e7481b37affc0c52..64da7359f3b2e80d32c208aa7eb542c34adf873c 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -91,19 +91,19 @@ namespace {
   template<Square Delta>
   inline Bitboard move_pawns(Bitboard p) {
 
-    return Delta == DELTA_N  ? p << 8 : Delta == DELTA_S  ? p >> 8 :
-           Delta == DELTA_NE ? p << 9 : Delta == DELTA_SE ? p >> 7 :
-           Delta == DELTA_NW ? p << 7 : Delta == DELTA_SW ? p >> 9 : p;
+    return  Delta == DELTA_N  ?  p << 8
+          : Delta == DELTA_S  ?  p >> 8
+          : Delta == DELTA_NE ? (p & ~FileHBB) << 9
+          : Delta == DELTA_SE ? (p & ~FileHBB) >> 7
+          : Delta == DELTA_NW ? (p & ~FileABB) << 7
+          : Delta == DELTA_SW ? (p & ~FileABB) >> 9 : p;
   }
 
 
   template<Square Delta>
   inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard target) {
 
-    const Bitboard TFileABB = (   Delta == DELTA_NE
-                               || Delta == DELTA_SE ? FileABB : FileHBB);
-
-    Bitboard b = move_pawns<Delta>(pawns) & target & ~TFileABB;
+    Bitboard b = move_pawns<Delta>(pawns) & target;
     SERIALIZE_PAWNS(b, -Delta);
     return mlist;
   }
@@ -112,14 +112,8 @@ namespace {
   template<MoveType Type, Square Delta>
   inline MoveStack* generate_promotions(MoveStack* mlist, Bitboard pawnsOn7, Bitboard target, Square ksq) {
 
-    const Bitboard TFileABB = (   Delta == DELTA_NE
-                               || Delta == DELTA_SE ? FileABB : FileHBB);
-
     Bitboard b = move_pawns<Delta>(pawnsOn7) & target;
 
-    if (Delta != DELTA_N && Delta != DELTA_S)
-        b &= ~TFileABB;
-
     while (b)
     {
         Square to = pop_1st_bit(&b);
@@ -141,12 +135,13 @@ namespace {
         else
             (void)ksq; // Silence a warning under MSVC
     }
+
     return mlist;
   }
 
 
   template<Color Us, MoveType Type>
-  MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {
+  MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq = SQ_NONE) {
 
     // Calculate our parametrized parameters at compile time, named according to
     // the point of view of white side.
@@ -251,14 +246,13 @@ namespace {
                                            Color us, const CheckInfo& ci) {
     assert(Pt != KING && Pt != PAWN);
 
-    Bitboard checkSqs, b;
     Square from;
     const Square* pl = pos.piece_list(us, Pt);
 
     if ((from = *pl++) == SQ_NONE)
         return mlist;
 
-    checkSqs = ci.checkSq[Pt] & pos.empty_squares();
+    Bitboard checkSqs = ci.checkSq[Pt] & pos.empty_squares();
 
     do
     {
@@ -269,7 +263,7 @@ namespace {
         if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
             continue;
 
-        b = pos.attacks_from<Pt>(from) & checkSqs;
+        Bitboard b = pos.attacks_from<Pt>(from) & checkSqs;
         SERIALIZE(b);
 
     } while ((from = *pl++) != SQ_NONE);
@@ -278,24 +272,6 @@ namespace {
   }
 
 
-  template<>
-  FORCE_INLINE MoveStack* generate_direct_checks<PAWN>(const Position& p, MoveStack* m,
-                                                       Color us, const CheckInfo& ci) {
-
-    return us == WHITE ? generate_pawn_moves<WHITE, MV_NON_CAPTURE_CHECK>(p, m, ci.dcCandidates, ci.ksq)
-                       : generate_pawn_moves<BLACK, MV_NON_CAPTURE_CHECK>(p, m, ci.dcCandidates, ci.ksq);
-  }
-
-
-  template<PieceType Pt, MoveType Type>
-  FORCE_INLINE MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us, Bitboard t) {
-
-    assert(Pt == PAWN);
-    return us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m, t, SQ_NONE)
-                       : generate_pawn_moves<BLACK, Type>(p, m, t, SQ_NONE);
-  }
-
-
   template<PieceType Pt>
   FORCE_INLINE MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
 
@@ -311,6 +287,7 @@ namespace {
             SERIALIZE(b);
         } while (*++pl != SQ_NONE);
     }
+
     return mlist;
   }
 
@@ -354,7 +331,9 @@ MoveStack* generate(const Position& pos, MoveStack* mlist) {
   else if (Type == MV_NON_EVASION)
       target = pos.pieces(~us) | pos.empty_squares();
 
-  mlist = generate_piece_moves<PAWN, Type>(pos, mlist, us, target);
+  mlist = (us == WHITE ? generate_pawn_moves<WHITE, Type>(pos, mlist, target)
+                       : generate_pawn_moves<BLACK, Type>(pos, mlist, target));
+
   mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
   mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
   mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
@@ -403,7 +382,9 @@ MoveStack* generate<MV_NON_CAPTURE_CHECK>(const Position& pos, MoveStack* mlist)
      SERIALIZE(b);
   }
 
-  mlist = generate_direct_checks<PAWN>(pos, mlist, us, ci);
+  mlist = (us == WHITE ? generate_pawn_moves<WHITE, MV_NON_CAPTURE_CHECK>(pos, mlist, ci.dcCandidates, ci.ksq)
+                       : generate_pawn_moves<BLACK, MV_NON_CAPTURE_CHECK>(pos, mlist, ci.dcCandidates, ci.ksq));
+
   mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, ci);
   mlist = generate_direct_checks<BISHOP>(pos, mlist, us, ci);
   mlist = generate_direct_checks<ROOK>(pos, mlist, us, ci);
@@ -480,7 +461,9 @@ MoveStack* generate<MV_EVASION>(const Position& pos, MoveStack* mlist) {
   // Blocking evasions or captures of the checking piece
   target = squares_between(checksq, ksq) | checkers;
 
-  mlist = generate_piece_moves<PAWN, MV_EVASION>(pos, mlist, us, target);
+  mlist = (us == WHITE ? generate_pawn_moves<WHITE, MV_EVASION>(pos, mlist, target)
+                       : generate_pawn_moves<BLACK, MV_EVASION>(pos, mlist, target));
+
   mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
   mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
   mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);