src/engine/moves/queen.c


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

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

  bitboard_t friendly_queens;
  bitboard_t friendly_pieces;
  bitboard_t enemy_pieces;
  if (position.turn == WHITE_TURN) {
    friendly_pieces = whites(position);
    enemy_pieces = blacks(position);
    friendly_queens = position.bitboards[WHITE_QUEEN];
  } else {
    friendly_pieces = blacks(position);
    enemy_pieces = whites(position);
    friendly_queens = position.bitboards[BLACK_QUEEN];
  }

  bitboard_t all_occupied = friendly_pieces | enemy_pieces;
  bitboard_t queens = friendly_queens;
  while (queens) {
    int from = __builtin_ctzll(queens);
    queens &= queens - 1;
    bitboard_t attacks = (get_rook_attacks(from, all_occupied) |
                          get_bishop_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);
    }
  }
}