void star_move(star_t* st) {
int x, y, z;
z = (st->z -= 1);
x = (st->x / z) + 128;
y = (st->y / z) + 96;
if (z < 1|| x < 0 || x >= MODE2_WIDTH || y < 0 || y >= MODE2_HEIGHT) {
star_randomize(st);
z = st->z;
x = (st->x / z) + 128;
y = (st->y / z) + 96;
}
st->last = st->addr;
st->addr = map_pixel(x, y);
st->sub = map_subpixel(x);
}
void pset(int x, int y) {
vmerge(map_pixel(x,y), map_subpixel(x));
}