stellar

commit 7ee440bb0ac6b207d99d69730ba6002bb908d96c
parent a5f8800b539804350d13c2d53d198c97a52bdfa1
Author: Dimitrije Dobrota <mail@dimitrijedobrota.com>
Date:   Mon, 19 Sep 2022 19:18:23 +0200

Knight attack mask

Diffstat:
M
src/engine.c
 | 
21
++++++++++++++++++++-

1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/src/engine.c b/src/engine.c
@@ -119,6 +119,9 @@ void bitboard_print(U64 bitboard) {
 // pawn attack table [side][square]
 U64 pawn_attacks[2][64];
 
+// knight attack table [square]
+U64 knight_attacks[64];
+
 // generate pawn attack
 U64 mask_pawn_attacks(int side, int square) {
   U64 bitboard = C64(0), attacks;
@@ -130,11 +133,27 @@ U64 mask_pawn_attacks(int side, int square) {
     return soWeOne(bitboard) | soEaOne(bitboard);
 }
 
+U64 mask_knight_attacks(int square) {
+  U64 bitboard = C64(0), attacks = C64(0), tmp;
+
+  bit_set(bitboard, square);
+  tmp = nortOne(nortOne(bitboard));
+  attacks |= westOne(tmp) | eastOne(tmp);
+  tmp = soutOne(soutOne(bitboard));
+  attacks |= westOne(tmp) | eastOne(tmp);
+  tmp = westOne(westOne(bitboard));
+  attacks |= soutOne(tmp) | nortOne(tmp);
+  tmp = eastOne(eastOne(bitboard));
+  attacks |= soutOne(tmp) | nortOne(tmp);
+
+  return attacks;
+}
+
 void init_leapers_attacks(void) {
   for (int square = 0; square < 64; square++) {
     pawn_attacks[WHITE][square] = mask_pawn_attacks(WHITE, square);
     pawn_attacks[BLACK][square] = mask_pawn_attacks(BLACK, square);
-    bitboard_print(pawn_attacks[WHITE][square]);
+    knight_attacks[square] = mask_knight_attacks(square);
   }
 }