diff --git a/engine/src/bitboard.c b/engine/src/bitboard.c index f34239c..c8cad1c 100644 --- a/engine/src/bitboard.c +++ b/engine/src/bitboard.c @@ -76,6 +76,53 @@ static int pop_lsb_index(uint64_t *bb) { return idx; } +static inline uint64_t ray_attacks(int start_square, int delta_file, int delta_rank, uint64_t occupied) +{ + uint64_t attacks = 0; + + int start_file = start_square % 8; + int start_rank = start_square / 8; + + int next_file = start_file + delta_file; + int next_rank = start_rank + delta_rank; + + while (next_file >= 0 && next_file < 8 && next_rank >= 0 && next_rank < 8) { + int next_square = next_rank * 8 + next_file; + uint64_t next_bit = 1ULL << next_square; + + // can attack this square + attacks |= next_bit; + + // blocker: include it, then stop + if (occupied & next_bit) + break; + + next_file += delta_file; + next_rank += delta_rank; + } + + return attacks; +} + +static inline uint64_t rook_attacks(int square, uint64_t occupied) { + return ray_attacks(square, +1, 0, occupied) // east + | ray_attacks(square, -1, 0, occupied) // west + | ray_attacks(square, 0, +1, occupied) // north + | ray_attacks(square, 0, -1, occupied); // south +} + +static inline uint64_t bishop_attacks(int square, uint64_t occupied) { + return ray_attacks(square, +1, +1, occupied) // NE + | ray_attacks(square, -1, +1, occupied) // NW + | ray_attacks(square, +1, -1, occupied) // SE + | ray_attacks(square, -1, -1, occupied); // SW +} + +static inline uint64_t queen_attacks(int square, uint64_t occupied) { + // Simply combine both types of attacks + return rook_attacks(square, occupied) | bishop_attacks(square, occupied); +} + void print_board(const struct Board *b) { static const char PIECE_CH[12] = { 'P','N','B','R','Q','K',