bool pseudo_is_legal(int move, board_t * board) {
int me, opp;
int from, to;
int piece;
bool legal;
int king;
undo_t undo[1];
ASSERT(move_is_ok(move));
ASSERT(board!=NULL);
// init
me = board->turn;
opp = COLOUR_OPP(me);
from = MOVE_FROM(move);
to = MOVE_TO(move);
piece = board->square[from];
ASSERT(COLOUR_IS(piece,me));
// slow test for en-passant captures
if (MOVE_IS_EN_PASSANT(move)) {
move_do(board,move,undo);
legal = !IS_IN_CHECK(board,me);
move_undo(board,move,undo);
return legal;
}
// king moves (including castle)
if (PIECE_IS_KING(piece)) {
legal = !is_attacked(board,to,opp);
if (DEBUG) {
ASSERT(board->square[from]==piece);
board->square[from] = Empty;
ASSERT(legal==!is_attacked(board,to,opp));
board->square[from] = piece;
}
return legal;
}
// pins
if (is_pinned(board,from,me)) {
king = KING_POS(board,me);
return DELTA_INC_LINE(king-to) == DELTA_INC_LINE(king-from); // does not discover the line
}
return true;
}
static void add_check(list_t * list, int move, board_t * board) {
undo_t undo[1];
ASSERT(list!=NULL);
ASSERT(move_is_ok(move));
ASSERT(board!=NULL);
move_do(board,move,undo);
if (IS_IN_CHECK(board,board->turn)) LIST_ADD(list,move);
move_undo(board,move,undo);
}
bool move_is_check(int move, board_t * board) {
undo_t undo[1];
bool check;
int me, opp, king;
int from, to, piece;
ASSERT(move_is_ok(move));
ASSERT(board!=NULL);
// slow test for complex moves
if (MOVE_IS_SPECIAL(move)) {
move_do(board,move,undo);
check = IS_IN_CHECK(board,board->turn);
move_undo(board,move,undo);
return check;
}
// init
me = board->turn;
opp = COLOUR_OPP(me);
king = KING_POS(board,opp);
from = MOVE_FROM(move);
to = MOVE_TO(move);
piece = board->square[from];
ASSERT(COLOUR_IS(piece,me));
// direct check
if (PIECE_ATTACK(board,piece,to,king)) return true;
// indirect check
if (is_pinned(board,from,opp)
&& DELTA_INC_LINE(king-to) != DELTA_INC_LINE(king-from)) {
return true;
}
return false;
}
bool board_is_stalemate(board_t * board) {
list_t list[1];
int i, move;
ASSERT(board!=NULL);
// init
if (IS_IN_CHECK(board,board->turn)) return false; // in check => not stalemate
// move loop
gen_moves(list,board);
for (i = 0; i < LIST_SIZE(list); i++) {
move = LIST_MOVE(list,i);
if (pseudo_is_legal(move,board)) return false; // legal move => not stalemate
}
return true; // in check and no legal move => mate
}
bool board_is_check(const board_t * board) {
ASSERT(board!=NULL);
return IS_IN_CHECK(board,board->turn);
}
bool board_is_legal(const board_t * board) {
ASSERT(board!=NULL);
return !IS_IN_CHECK(board,COLOUR_OPP(board->turn));
}
