Use different input & output in bidirectional lines

[nicx82]

I have a component with 38 bidirectional lines. I want that the user can set how many inputs and how many outputs can use through an internal signal that store the number of inputs and the numbers of output. E.g. if the user choose 13 output and 7 input the component must send the output to lines (38 downto 26) and receive input from lines (25 down to 19). How can i implement this component?

Thanks