add bb_pawn_attacks[][], bb_shift()

src/bitboard.h

@@ -39,9 +39,8 @@ extern bitboard_t bb_sqrank[64], bb_sqfile[64], bb_sqdiag[64], bb_sqanti[64];
 /* line (rank, file, diagonal or anti-diagonal) between two squares */
 extern bitboard_t bb_line[64][64];
 
-/* knight and king moves */
-extern bitboard_t bb_knight[64], bb_king[64];
-
+/* pawn, knight and king attacks */
+extern bitboard_t bb_knight[64], bb_king[64], bb_pawn_attacks[2][64];
 
 /* TODO (maybe C23?) when we can ensure an enum can be u64
  *
@@ -222,11 +221,25 @@ static __always_inline bool bb_multiple(bitboard_t bb)
     return !!(bb & (bb - 1));
 }
 
+/**
+ * bb_shift() - shift bitboard
+ * @bb: bitboard
+ *
+ * No control is done on off-board shifting (i.e. shifting -1 from A2 gives H3).
+ *
+ * @return: true if @bb has more than 1 bit, false otherwise.
+ */
+static __always_inline bitboard_t bb_shift(bitboard_t bb, int shift)
+{
+   return shift >= 0 ? bb << shift : bb >> -shift;
+}
+
 
 #define bb_rank(r)        ((u64) RANK_1bb << ((r) * 8))
 #define bb_file(f)        ((u64) FILE_Abb << (f))
 
 #define bb_rel_rank(r, c) bb_rank(sq_rel_rank(r, c))
+#define bb_rel_file(f, c) bb_file(sq_rel_rank(f, c))
 
 /**
  * bb_sq_aligned() - check if two squares are aligned (same file or rank).
@@ -301,6 +314,9 @@ static __always_inline bitboard_t shift_nw(const bitboard_t bb)
 #define pawn_shift_up(bb, c)      ((c) == WHITE ? shift_n(bb): shift_s(bb))
 #define pawn_shift_upleft(bb, c)  ((c) == WHITE ? shift_nw(bb): shift_se(bb))
 #define pawn_shift_upright(bb, c) ((c) == WHITE ? shift_ne(bb): shift_sw(bb))
+#define pawn_attacks_bb(bb, c)    (pawn_shift_upleft(bb, c) |                   \
+                                   pawn_shift_upright(bb, c))
+
 /* pawn move (for single pawn) - NO SQUARE CONTROL HERE !
  * Need to make functions with control instead.
  */