/* 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();
}
/* Intercept with a black piece
* @param 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 black_piece(square target, int dir_from_rider, void (*go_on)(void))
{
Flags const mask = BIT(Black)|BIT(Royal);
boolean const is_check = TSTFULLFLAGMASK(being_solved.spec[target+dir_from_rider],mask);
square where_to_intercept;
TraceFunctionEntry(__func__);
TraceSquare(target);
TraceFunctionParam("%d",dir_from_rider);
TraceFunctionParamListEnd();
for (where_to_intercept = target-dir_from_rider;
is_square_empty(where_to_intercept);
where_to_intercept -= dir_from_rider)
if (nr_reasons_for_staying_empty[where_to_intercept]==0
/* avoid testing the same position twice */
&& *where_to_start_placing_black_pieces<=where_to_intercept)
black_piece_on(is_check,where_to_intercept,go_on);
TraceFunctionExit(__func__);
TraceFunctionResultEnd();
}