Simplify generate_pawn_captures()

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 076af3fe0c48b15b8dab329841c8dc3ef9f62624..866f4d0705a880e80cf15803dae671809c1328d2 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -444,34 +444,26 @@ namespace {
     return mlist;
   }
 
-  template<Color Us, SquareDelta Direction>
+  template<SquareDelta Delta>
   inline Bitboard move_pawns(Bitboard p) {
 
-    if (Direction == DELTA_N)
-        return Us == WHITE ? p << 8 : p >> 8;
-    else if (Direction == DELTA_NE)
-        return Us == WHITE ? p << 9 : p >> 7;
-    else if (Direction == DELTA_NW)
-        return Us == WHITE ? p << 7 : p >> 9;
-    else
-        return 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;
   }
 
-  template<Color Us, MoveType Type, SquareDelta Diagonal>
-  inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces) {
+  template<Color Us, MoveType Type, SquareDelta Delta>
+  inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard target) {
 
     // Calculate our parametrized parameters at compile time
     const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
-    const Bitboard TFileABB = (Diagonal == DELTA_NE ? FileABB : FileHBB);
-    const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
-    const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
-    const SquareDelta TTDELTA_NE = (Diagonal == DELTA_NE ? TDELTA_NE : TDELTA_NW);
+    const Bitboard TFileABB = (Delta == DELTA_NE || Delta == DELTA_SE ? FileABB : FileHBB);
 
     Bitboard b1, b2;
     Square to;
 
     // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
-    b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
+    b1 = move_pawns<Delta>(pawns) & ~TFileABB & target;
 
     // Capturing promotions and under-promotions
     if (b1 & TRank8BB)
@@ -483,26 +475,26 @@ namespace {
             to = pop_1st_bit(&b2);
 
             if (Type == CAPTURE || Type == EVASION)
-                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
+                (*mlist++).move = make_promotion_move(to - Delta, to, QUEEN);
 
             if (Type == NON_CAPTURE || Type == EVASION)
             {
-                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, ROOK);
-                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, BISHOP);
-                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, KNIGHT);
+                (*mlist++).move = make_promotion_move(to - Delta, to, ROOK);
+                (*mlist++).move = make_promotion_move(to - Delta, to, BISHOP);
+                (*mlist++).move = make_promotion_move(to - Delta, to, KNIGHT);
             }
 
             // This is the only possible under promotion that can give a check
             // not already included in the queen-promotion. It is not sure that
             // the promoted knight will give check, but it doesn't worth to verify.
             if (Type == CHECK)
-                (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, KNIGHT);
+                (*mlist++).move = make_promotion_move(to - Delta, to, KNIGHT);
         }
     }
 
     // Serialize standard captures
     if (Type == CAPTURE || Type == EVASION)
-        SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
+        SERIALIZE_MOVES_D(b1, -Delta);
 
     return mlist;
   }
@@ -515,7 +507,9 @@ namespace {
     const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
     const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
     const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
-    const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+    const SquareDelta TDELTA_N  = (Us == WHITE ? DELTA_N  : DELTA_S);
+    const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
+    const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
 
     Square to;
     Bitboard b1, b2, enemyPieces, emptySquares;
@@ -529,14 +523,14 @@ namespace {
         if (Type == EVASION)
             enemyPieces &= target; // Capture only the checker piece
 
-        mlist = generate_pawn_captures<Us, Type, DELTA_NE>(mlist, pawns, enemyPieces);
-        mlist = generate_pawn_captures<Us, Type, DELTA_NW>(mlist, pawns, enemyPieces);
+        mlist = generate_pawn_captures<Us, Type, TDELTA_NE>(mlist, pawns, enemyPieces);
+        mlist = generate_pawn_captures<Us, Type, TDELTA_NW>(mlist, pawns, enemyPieces);
     }
 
     // Non-capturing promotions and underpromotions
     if (pawns & TRank7BB)
     {
-        b1 = move_pawns<Us, DELTA_N>(pawns) & TRank8BB & pos.empty_squares();
+        b1 = move_pawns<TDELTA_N>(pawns) & TRank8BB & pos.empty_squares();
 
         if (Type == EVASION)
             b1 &= target; // Only blocking promotion pushes
@@ -568,8 +562,8 @@ namespace {
         emptySquares = (Type == NON_CAPTURE ? target : pos.empty_squares());
 
         // Single and double pawn pushes
-        b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
-        b2 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
+        b1 = move_pawns<TDELTA_N>(pawns) & emptySquares & ~TRank8BB;
+        b2 = move_pawns<TDELTA_N>(b1 & TRank3BB) & emptySquares;
 
         // Filter out unwanted pushes according to the move type
         if (Type == EVASION)
@@ -588,8 +582,8 @@ namespace {
             //  don't generate captures.
             if (pawns & target) // For CHECK type target is dc bitboard
             {
-                Bitboard dc1 = move_pawns<Us, DELTA_N>(pawns & target & ~file_bb(ksq)) & emptySquares & ~TRank8BB;
-                Bitboard dc2 = move_pawns<Us, DELTA_N>(dc1 & TRank3BB) & emptySquares;
+                Bitboard dc1 = move_pawns<TDELTA_N>(pawns & target & ~file_bb(ksq)) & emptySquares & ~TRank8BB;
+                Bitboard dc2 = move_pawns<TDELTA_N>(dc1 & TRank3BB) & emptySquares;
 
                 b1 |= dc1;
                 b2 |= dc2;