bitmap_t
bitmap_t bitmap; // bitmap for the slots if we are a leaf
node->u.bitmap = (bitmap_t)-1 << big_hint;
bitmap_t bitmap = ~leaf->u.bitmap;
bitmap_t mask = (bitmap_t)-1 >> n;
bitmap_t mask = ((bitmap_t)-1 >> (BITMAP_RADIX - count - n))
& ((bitmap_t)-1 << n);