static void alists_hidden(alists_t * alists, const board_t * board, int from, int to) {
int inc;
int sq, piece;
ASSERT(alists!=NULL);
ASSERT(board!=NULL);
ASSERT(SQUARE_IS_OK(from));
ASSERT(SQUARE_IS_OK(to));
inc = DELTA_INC_LINE(to-from);
if (inc != IncNone) { // line
sq = from;
do sq -= inc; while ((piece=board->square[sq]) == Empty);
if (SLIDER_ATTACK(piece,inc)) {
ASSERT(piece_is_ok(piece));
ASSERT(PIECE_IS_SLIDER(piece));
alist_add(alists->alist[PIECE_COLOUR(piece)],sq,board);
}
}
}
bool is_pinned(const board_t * board, int square, int colour) {
int from, to;
int inc;
int sq, piece;
ASSERT(board!=NULL);
ASSERT(SQUARE_IS_OK(square));
ASSERT(COLOUR_IS_OK(colour));
from = square;
to = KING_POS(board,colour);
inc = DELTA_INC_LINE(to-from);
if (inc == IncNone) return false; // not a line
sq = from;
do sq += inc; while (board->square[sq] == Empty);
if (sq != to) return false; // blocker
sq = from;
do sq -= inc; while ((piece=board->square[sq]) == Empty);
return COLOUR_IS(piece,COLOUR_OPP(colour)) && SLIDER_ATTACK(piece,inc);
}
static void find_pins(int list[], const board_t * board) {
int me, opp;
int king;
const sq_t * ptr;
int from;
int piece;
int delta;
int inc;
int sq;
int capture;
int pin;
ASSERT(list!=NULL);
ASSERT(board!=NULL);
// init
me = board->turn;
opp = COLOUR_OPP(me);
king = KING_POS(board,opp);
for (ptr = &board->piece[me][1]; (from=*ptr) != SquareNone; ptr++) { // HACK: no king
piece = board->square[from];
delta = king - from;
ASSERT(delta_is_ok(delta));
if (PSEUDO_ATTACK(piece,delta)) {
ASSERT(PIECE_IS_SLIDER(piece));
inc = DELTA_INC_LINE(delta);
ASSERT(inc!=IncNone);
ASSERT(SLIDER_ATTACK(piece,inc));
sq = from;
do sq += inc;
while ((capture=board->square[sq]) == Empty);
ASSERT(sq!=king);
if (COLOUR_IS(capture,me)) {
pin = sq;
do sq += inc;
while (board->square[sq] == Empty);
if (sq == king) *list++ = pin;
}
}
}
*list = SquareNone;
}