Reading values from a memory address in Ada - ada

Question

I am trying to write a procedure that given a memory address and data type, will display the value of the data at that memory location.
I'm thinking that the best way to do this would be to use the To_Pointer function in the generic package Address_To_Access_Conversions, but every time I try to use it I get an error:
invalid prefix in selected component "Address_To_Access_Conversions"
I've ben unable to find any examples of how the Address_To_Access_Conversions is actually used. And I may be on the totally wrong track.
Does anyone know how to use the above package to convert an Address to an Access type and more importantly, a good way to access data at a given address to display to console?
Edit
The solution I found most in my research was to use something like the following:
for X'Address use dummy_address;
The only problem was that at that point in the code, I hadn't calculated what the dummy address was and that statement would only work at declaration, before 'begin' I found a way around this though with block programming:
dummy_address := base_address + offset;
Dummy_String:
declare
subtype Xdummy is Integer;
S : Xdummy;
for S'Address use dummy_address;
begin
--More code here
end Dummy_String;