src/engine/moves/rook.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45

#define MOVES_INTERNAL
#include "engine/moves.h"

void __forloop_rook_moves_gen(
  moves_t* moves,
  bitboard_t friendly_type,
  bitboard_t friendly_pieces,
  bitboard_t enemy_pieces
) {
  bitboard_t all_occupied = friendly_pieces | enemy_pieces;
  while (friendly_type) {
    int from = __builtin_ctzll(friendly_type);
    friendly_type &= friendly_type - 1;
    bitboard_t attacks = get_rook_attacks(from, all_occupied) & ~friendly_pieces;
    while (attacks) {
      int to = __builtin_ctzll(attacks);
      attacks &= attacks - 1;
      add_move(moves, from, to, .flags = ((enemy_pieces >> to) & 1) ? MOVE_CAPTURE : 0);
    }
  }
}

void get_rook_moves(moves_t* moves, position_t position) {
  assert_valid_position(position);

  bitboard_t friendly_rooks;
  bitboard_t friendly_pieces;
  bitboard_t enemy_pieces;
  if (position.turn == WHITE_TURN) {
    friendly_pieces = whites(position);
    enemy_pieces = blacks(position);
    friendly_rooks = position.bitboards[WHITE_ROOK];
  } else {
    friendly_pieces = blacks(position);
    enemy_pieces = whites(position);
    friendly_rooks = position.bitboards[BLACK_ROOK];
  }
  
  __forloop_rook_moves_gen(
    moves,
    friendly_rooks,
    friendly_pieces,
    enemy_pieces
  );
}