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fix king move in pos_is_legal()

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Bruno Raoult
2024-03-15 09:12:42 +01:00
parent c8aea61529
commit 92dcb1e778
1 changed files with 34 additions and 15 deletions
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49
src/move-gen.c
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@@ -37,43 +37,62 @@
bool pseudo_is_legal(pos_t *pos, move_t move)
{
color_t us = pos->turn, them = OPPONENT(us);
square_t from = move_from(move), to = move_to(move);
int piece = PIECE(pos->board[from]), sq;
bitboard_t tmp;
square_t from = move_from(move), to = move_to(move), king = pos->king[us], sq;
piece_type_t piece = PIECE(pos->board[from]);
bitboard_t kingbb = pos->bb[us][KING], tmp;
/* (1) - King
* For castling, we already tested intermediate squares attacks
* in pseudo move generation, so we only care destination square here.
* Attention: We need to exclude king from occupation bitboard !
*/
if (piece == KING)
return !sq_attackers(pos, to, them);
if (piece == KING) {
bitboard_t occ = pos_occ(pos) ^ kingbb;
return !sq_attackers(pos, occ, to, them);
}
/* (2) - pinned pieces
/* (2) - King is in check
* Double-check is already handled, as only K moves were generated.
* Here, allowed moves are only on King-attacker line, including
* attacker.We can move a piece on
* in pseudo move generation, so we only care destination square here.
*/
if (pos->checkers) {
if (popcount64(pos->checkers) == 1) { /* one checker */
square_t checker = ctz64(pos->checkers);
bitboard_t between = bb_between[king][checker];
return mask(to) & between;
}
return false; /* double check */
}
/* (3) - pinned pieces
* We verify here that pinned piece P stays on line King-P.
*/
if (mask(from) & pos->blockers & pos->bb[us][ALL_PIECES]) {
bitboard_t line = bb_line[from][pos->king[us]];
bitboard_t line = bb_line[from][king];
return line & mask(to); /* to is not on pin line */
}
/* (3) - En-passant
/* (4) - En-passant
* We only care the situation where our King and enemy R/Q are on
* from rank ()
* 5th relative rank. To do so, we create an occupation bb without
* the 2 pawns.
*/
if (move & M_CAPTURE && PIECE(pos->board[to]) == EMPTY) {
/* from square rank bitboard */
bitboard_t rank5 = bb_sqrank[sq_rank(from)];
/* from rank bitboard */
bitboard_t rank5 = bb_sqrank[from];
/* enemy rooks/queens on from rank */
bitboard_t rooks = (pos->bb[them][ROOK] | pos->bb[them][QUEEN]) & rank5;
if ((pos->bb[us][KING] & rank5) && rooks) { /* K and enemy R/Q on rank */
if ((kingbb & rank5) && rooks) { /* K and enemy R/Q on rank */
/* captured pawn square (beside from square) */
square_t captured = sq_make(sq_file(pos->en_passant), sq_rank(from));
/* occupation bitboard without the two "disappearing" pawns */
bitboard_t occ = pos_occ(pos) ^ mask(from) ^ mask(captured);
bit_for_each64(sq, tmp, rooks) /* check all rooks/queens */
if (hyperbola_rank_moves(occ, sq) & pos->bb[us][KING])
if (hyperbola_rank_moves(occ, sq) & kingbb)
return false;
}
return true;
@@ -246,14 +265,14 @@ int pos_gen_pseudomoves(pos_t *pos)
if (CAN_OO(pos->castle, us)) {
bitboard_t occmask = rel_rank1 & (FILE_Fbb | FILE_Gbb);
if (!(occ & occmask) &&
!sq_attackers(pos, from+1, them)) { /* f1/f8 */
!sq_attackers(pos, occ, from+1, them)) { /* f1/f8 */
moves[nmoves++] = move_make_flags(from, from + 2, M_CASTLE_K);
}
}
if (CAN_OOO(pos->castle, us)) {
bitboard_t occmask = rel_rank1 & (FILE_Bbb | FILE_Cbb | FILE_Dbb);
if (!(occ & occmask) &&
!sq_attackers(pos, from-1, them)) { /* d1/d8 */
!sq_attackers(pos, occ, from-1, them)) { /* d1/d8 */
moves[nmoves++] = move_make_flags(from, from - 2, M_CASTLE_Q);
}
}