/* Is the placed white king in check from a particular direction?
* @param dir direction
* @return true iff the placed white king is in check from dir
*/
static boolean check_from_direction(int dir)
{
square curr = being_solved.king_square[White]-dir;
boolean const is_diagonal = SquareCol(curr)==SquareCol(being_solved.king_square[White]);
boolean result;
TraceFunctionEntry(__func__);
TraceFunctionParam("%d",dir);
TraceFunctionParamListEnd();
while (is_square_empty(curr))
curr -= dir;
if (TSTFLAG(being_solved.spec[curr],Black))
{
piece_walk_type const checker = get_walk_of_piece_on_square(curr);
result = checker==Queen || checker==(is_diagonal ? Bishop : Rook);
}
else
result = false;
TraceFunctionExit(__func__);
TraceFunctionResult("%u",result);
TraceFunctionResultEnd();
return result;
}
/* Intercept with a white piece
* @param target guard of what square
* @param dir_from_rider direction from rider giving check to black king
* @param go_on what to do after each successful interception?
*/
static void white_piece(square target, int dir_from_rider, void (*go_on)(void))
{
square const start = target-dir_from_rider;
boolean const is_diagonal = SquareCol(start)==SquareCol(target);
square where_to_intercept;
TraceFunctionEntry(__func__);
TraceSquare(target);
TraceFunctionParam("%d",dir_from_rider);
TraceFunctionParamListEnd();
for (where_to_intercept = start;
is_square_empty(where_to_intercept);
where_to_intercept -= dir_from_rider)
if (nr_reasons_for_staying_empty[where_to_intercept]==0)
white_piece_on(where_to_intercept,is_diagonal,go_on);
TraceFunctionExit(__func__);
TraceFunctionResultEnd();
}
/* Intercept a check to the white king with a black piece
* @param dir_from_rider direction from rider giving check to white king
* @param go_on what to do after each successful interception?
*/
static void black_piece(slice_index si,
int dir_to_rider,
void (*go_on)(slice_index si))
{
square const start = being_solved.king_square[White]-dir_to_rider;
boolean const is_diagonal = SquareCol(being_solved.king_square[White])==SquareCol(start);
square where_to_intercept;
TraceFunctionEntry(__func__);
TraceFunctionParam("%d",dir_to_rider);
TraceFunctionParamListEnd();
for (where_to_intercept = start;
is_square_empty(where_to_intercept);
where_to_intercept -= dir_to_rider)
if (nr_reasons_for_staying_empty[where_to_intercept]==0
&& *where_to_start_placing_black_pieces<=where_to_intercept)
black_piece_on(si,where_to_intercept,is_diagonal,go_on);
TraceFunctionExit(__func__);
TraceFunctionResultEnd();
}
