stellar

0 #ifndef STELLAR_ATTACK_KNIGHT_H

1 #define STELLAR_ATTACK_KNIGHT_H

2

3 #include "bit.hpp"

4 #include "bitboard.hpp"

5 #include "utils.hpp"

6

7 #include <array>

8

9 namespace attack {

10 namespace knight {

11

12 static constexpr U64 mask(const Square square) {

13 U64 bitboard = C64(0), attacks = C64(0), tmp;

14

15 bit::set(bitboard, square);

16 tmp = bitboard::nortOne(bitboard::nortOne(bitboard));

17 attacks |= bitboard::westOne(tmp) | bitboard::eastOne(tmp);

18 tmp = bitboard::soutOne(bitboard::soutOne(bitboard));

19 attacks |= bitboard::westOne(tmp) | bitboard::eastOne(tmp);

20 tmp = bitboard::westOne(bitboard::westOne(bitboard));

21 attacks |= bitboard::soutOne(tmp) | bitboard::nortOne(tmp);

22 tmp = bitboard::eastOne(bitboard::eastOne(bitboard));

23 attacks |= bitboard::soutOne(tmp) | bitboard::nortOne(tmp);

24

25 return attacks;

26 }

27

28 typedef std::array<U64, 64> attack_array;

29 const attack_array attacks = []() -> attack_array {

30 std::array<U64, 64> attacks;

31

32 for (Square square = Square::a1; square <= Square::h8; ++square) {

33 attacks[square] = mask(square);

34 }

35

36 return attacks;

37 }();

38

39 inline constexpr U64 attack(const Square square) { return attacks[square]; }

40

41 } // namespace knight

42 } // namespace attack

43

44 #endif