static bool simple_stalemate(const board_t * board) {
int me, opp;
int king;
int opp_flag;
int from, to;
int capture;
const inc_t * inc_ptr;
int inc;
ASSERT(board!=NULL);
ASSERT(board_is_legal(board));
ASSERT(!board_is_check(board));
// lone king?
me = board->turn;
if (board->piece_size[me] != 1 || board->pawn_size[me] != 0) return false; // no
// king in a corner?
king = KING_POS(board,me);
if (king != A1 && king != H1 && king != A8 && king != H8) return false; // no
// init
opp = COLOUR_OPP(me);
opp_flag = COLOUR_FLAG(opp);
// king can move?
from = king;
for (inc_ptr = KingInc; (inc=*inc_ptr) != IncNone; inc_ptr++) {
to = from + inc;
capture = board->square[to];
if (capture == Empty || FLAG_IS(capture,opp_flag)) {
if (!is_attacked(board,to,opp)) return false; // legal king move
}
}
// no legal move
ASSERT(board_is_stalemate((board_t*)board));
return true;
}
static void add_captures(list_t * list, const board_t * board) {
int me, opp;
int opp_flag;
const sq_t * ptr;
int from, to;
int piece, capture;
ASSERT(list!=NULL);
ASSERT(board!=NULL);
me = board->turn;
opp = COLOUR_OPP(me);
opp_flag = COLOUR_FLAG(opp);
// piece captures
for (ptr = &board->piece[me][0]; (from=*ptr) != SquareNone; ptr++) {
piece = board->square[from];
switch (PIECE_TYPE(piece)) {
case Knight64:
to = from - 33;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from - 31;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from - 18;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from - 14;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from + 14;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from + 18;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from + 31;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from + 33;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
break;
case Bishop64:
for (to = from-17; (capture=board->square[to]) == Empty; to -= 17)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from-15; (capture=board->square[to]) == Empty; to -= 15)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from+15; (capture=board->square[to]) == Empty; to += 15)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from+17; (capture=board->square[to]) == Empty; to += 17)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
break;
case Rook64:
for (to = from-16; (capture=board->square[to]) == Empty; to -= 16)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from-1; (capture=board->square[to]) == Empty; to -= 1)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from+1; (capture=board->square[to]) == Empty; to += 1)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from+16; (capture=board->square[to]) == Empty; to += 16)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
break;
case Queen64:
for (to = from-17; (capture=board->square[to]) == Empty; to -= 17)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from-16; (capture=board->square[to]) == Empty; to -= 16)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from-15; (capture=board->square[to]) == Empty; to -= 15)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from-1; (capture=board->square[to]) == Empty; to -= 1)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from+1; (capture=board->square[to]) == Empty; to += 1)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from+15; (capture=board->square[to]) == Empty; to += 15)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from+16; (capture=board->square[to]) == Empty; to += 16)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
for (to = from+17; (capture=board->square[to]) == Empty; to += 17)
;
if (FLAG_IS(capture,opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
break;
case King64:
to = from - 17;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from - 16;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from - 15;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from - 1;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from + 1;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from + 15;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from + 16;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
to = from + 17;
if (FLAG_IS(board->square[to],opp_flag)) LIST_ADD(list,MOVE_MAKE(from,to));
break;
default:
ASSERT(false);
break;
}
}
// pawn captures
if (COLOUR_IS_WHITE(me)) {
for (ptr = &board->pawn[me][0]; (from=*ptr) != SquareNone; ptr++) {
to = from + 15;
if (FLAG_IS(board->square[to],opp_flag)) add_pawn_move(list,from,to);
to = from + 17;
if (FLAG_IS(board->square[to],opp_flag)) add_pawn_move(list,from,to);
// promote
if (SQUARE_RANK(from) == Rank7) {
to = from + 16;
if (board->square[to] == Empty) {
add_promote(list,MOVE_MAKE(from,to));
}
}
}
} else { // black
for (ptr = &board->pawn[me][0]; (from=*ptr) != SquareNone; ptr++) {
to = from - 17;
if (FLAG_IS(board->square[to],opp_flag)) add_pawn_move(list,from,to);
to = from - 15;
if (FLAG_IS(board->square[to],opp_flag)) add_pawn_move(list,from,to);
// promote
if (SQUARE_RANK(from) == Rank2) {
to = from - 16;
if (board->square[to] == Empty) {
add_promote(list,MOVE_MAKE(from,to));
}
}
}
}
}
static void add_moves(list_t * list, const board_t * board) {
int me, opp;
int opp_flag;
const sq_t * ptr;
int from, to;
int piece, capture;
const inc_t * inc_ptr;
int inc;
ASSERT(list!=NULL);
ASSERT(board!=NULL);
me = board->turn;
opp = COLOUR_OPP(me);
opp_flag = COLOUR_FLAG(opp);
// piece moves
for (ptr = &board->piece[me][0]; (from=*ptr) != SquareNone; ptr++) {
piece = board->square[from];
inc_ptr = PIECE_INC(piece);
if (PIECE_IS_SLIDER(piece)) {
for (; (inc=*inc_ptr) != IncNone; inc_ptr++) {
for (to = from+inc; (capture=board->square[to]) == Empty; to += inc) {
LIST_ADD(list,MOVE_MAKE(from,to));
}
if (FLAG_IS(capture,opp_flag)) {
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
} else {
for (; (inc=*inc_ptr) != IncNone; inc_ptr++) {
to = from + inc;
capture = board->square[to];
if (capture == Empty || FLAG_IS(capture,opp_flag)) {
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
}
}
// pawn moves
inc = PAWN_MOVE_INC(me);
for (ptr = &board->pawn[me][0]; (from=*ptr) != SquareNone; ptr++) {
to = from + (inc-1);
if (FLAG_IS(board->square[to],opp_flag)) {
add_pawn_move(list,from,to);
}
to = from + (inc+1);
if (FLAG_IS(board->square[to],opp_flag)) {
add_pawn_move(list,from,to);
}
to = from + inc;
if (board->square[to] == Empty) {
add_pawn_move(list,from,to);
if (PAWN_RANK(from,me) == Rank2) {
to = from + (2*inc);
if (board->square[to] == Empty) {
ASSERT(!SQUARE_IS_PROMOTE(to));
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
}
}
}
static bool gen_evasions(list_t * list, const board_t * board, const attack_t * attack, bool legal, bool stop) {
int me, opp;
int opp_flag;
int king;
const inc_t * inc_ptr;
int inc;
int to;
int piece;
ASSERT(list!=NULL);
ASSERT(board!=NULL);
ASSERT(attack!=NULL);
ASSERT(legal==true||legal==false);
ASSERT(stop==true||stop==false);
ASSERT(board_is_check(board));
ASSERT(ATTACK_IN_CHECK(attack));
// init
LIST_CLEAR(list);
me = board->turn;
opp = COLOUR_OPP(me);
opp_flag = COLOUR_FLAG(opp);
king = KING_POS(board,me);
for (inc_ptr = KingInc; (inc=*inc_ptr) != IncNone; inc_ptr++) {
if (inc != -attack->di[0] && inc != -attack->di[1]) { // avoid escaping along a check line
to = king + inc;
piece = board->square[to];
if (piece == Empty || FLAG_IS(piece,opp_flag)) {
if (!legal || !is_attacked(board,to,opp)) {
if (stop) return true;
LIST_ADD(list,MOVE_MAKE(king,to));
}
}
}
}
if (attack->dn >= 2) return false; // double check, we are done
// single check
ASSERT(attack->dn==1);
// capture the checking piece
if (add_pawn_captures(list,board,attack->ds[0],legal,stop) && stop) return true;
if (add_piece_moves(list,board,attack->ds[0],legal,stop) && stop) return true;
// interpose a piece
inc = attack->di[0];
if (inc != IncNone) { // line
for (to = king+inc; to != attack->ds[0]; to += inc) {
ASSERT(SQUARE_IS_OK(to));
ASSERT(board->square[to]==Empty);
if (add_pawn_moves(list,board,to,legal,stop) && stop) return true;
if (add_piece_moves(list,board,to,legal,stop) && stop) return true;
}
}
return false;
}
