// returns 0 on illegal move
static Move parse_move(Bitboard *board, char* possible_move)
{
Movelist moves;
move_generate_movelist(board, &moves);
char test[6];
Moveiter it;
moveiter_init(&it, &moves, MOVEITER_SORT_NONE, MOVE_NULL);
while (moveiter_has_next(&it))
{
Move m = moveiter_next(&it);
move_srcdest_form(m, test);
if (!move_is_promotion(m) && !strncmp(test, possible_move, 4))
return m;
else if (!strncmp(test, possible_move, 5))
return m;
}
return 0;
}
bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) {
assert(pos.is_ok());
assert(move_is_ok(m));
assert(pinned == pos.pinned_pieces(pos.side_to_move()));
Color us = pos.side_to_move();
Color them = opposite_color(us);
Square from = move_from(m);
Square to = move_to(m);
Piece pc = pos.piece_on(from);
// Use a slower but simpler function for uncommon cases
if (move_is_ep(m) || move_is_castle(m))
return move_is_legal(pos, m);
// If the from square is not occupied by a piece belonging to the side to
// move, the move is obviously not legal.
if (color_of_piece(pc) != us)
return false;
// The destination square cannot be occupied by a friendly piece
if (pos.color_of_piece_on(to) == us)
return false;
// Handle the special case of a pawn move
if (type_of_piece(pc) == PAWN)
{
// Move direction must be compatible with pawn color
int direction = to - from;
if ((us == WHITE) != (direction > 0))
return false;
// A pawn move is a promotion iff the destination square is
// on the 8/1th rank.
if (( (square_rank(to) == RANK_8 && us == WHITE)
||(square_rank(to) == RANK_1 && us != WHITE)) != bool(move_is_promotion(m)))
return false;
// Proceed according to the square delta between the origin and
// destination squares.
switch (direction)
{
case DELTA_NW:
case DELTA_NE:
case DELTA_SW:
case DELTA_SE:
// Capture. The destination square must be occupied by an enemy
// piece (en passant captures was handled earlier).
if (pos.color_of_piece_on(to) != them)
return false;
break;
case DELTA_N:
case DELTA_S:
// Pawn push. The destination square must be empty.
if (!pos.square_is_empty(to))
return false;
break;
case DELTA_NN:
// Double white pawn push. The destination square must be on the fourth
// rank, and both the destination square and the square between the
// source and destination squares must be empty.
if ( square_rank(to) != RANK_4
|| !pos.square_is_empty(to)
|| !pos.square_is_empty(from + DELTA_N))
return false;
break;
case DELTA_SS:
// Double black pawn push. The destination square must be on the fifth
// rank, and both the destination square and the square between the
// source and destination squares must be empty.
if ( square_rank(to) != RANK_5
|| !pos.square_is_empty(to)
|| !pos.square_is_empty(from + DELTA_S))
return false;
break;
default:
return false;
}
// The move is pseudo-legal, check if it is also legal
return pos.is_check() ? pos.pl_move_is_evasion(m, pinned) : pos.pl_move_is_legal(m, pinned);
}
// Luckly we can handle all the other pieces in one go
return bit_is_set(pos.attacks_from(pc, from), to)
&& (pos.is_check() ? pos.pl_move_is_evasion(m, pinned) : pos.pl_move_is_legal(m, pinned))
&& !move_is_promotion(m);
}
