bool piece_attack(const board_t * board, int piece, int from, int to) {
int delta;
int inc, sq;
ASSERT(board_is_ok(board));
ASSERT(piece_is_ok(piece));
ASSERT(square_is_ok(from));
ASSERT(square_is_ok(to));
delta = to - from;
ASSERT(delta_is_ok(delta));
if ((piece & DELTA_MASK(delta)) == 0) return false; // no pseudo-attack
if (!piece_is_slider(piece)) return true;
inc = DELTA_INC(delta);
ASSERT(inc_is_ok(inc));
for (sq = from+inc; sq != to; sq += inc) {
ASSERT(square_is_ok(sq));
if (board->square[sq] != Empty) return false; // blocker
}
return true;
}
bool attack_is_ok(const attack_t * attack) {
int i;
int sq, inc;
if (attack == NULL) return false;
// checks
if (attack->dn < 0 || attack->dn > 2) return false;
for (i = 0; i < attack->dn; i++) {
sq = attack->ds[i];
if (!SQUARE_IS_OK(sq)) return false;
inc = attack->di[i];
if (inc != IncNone && !inc_is_ok(inc)) return false;
}
if (attack->ds[attack->dn] != SquareNone) return false;
if (attack->di[attack->dn] != IncNone) return false;
return true;
}
