node_maxindex
index &= ~node_maxindex(node);
iter->index = (index &~ node_maxindex(node)) | offset;
iter->next_index = (index | node_maxindex(node)) + 1;
iter->next_index = 1 + min(max, (start | node_maxindex(node)));
return (index & ~node_maxindex(node)) + (offset << node->shift);
*maxindex = node_maxindex(node);
assert(maxindex <= node_maxindex(node));
unsigned long node_maxindex(struct radix_tree_node *);