Implement map_addr functions

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

hw2/bin/simulator.ml

@@ -179,14 +179,23 @@ let interp_cnd { fo; fs; fz } : cnd -> bool = function
 
 (* Maps an X86lite address into Some OCaml array index,
    or None if the address is not within the legal address space. *)
-let map_addr (addr : quad) : int option = failwith "map_addr not implemented"
+let map_addr (addr : quad) : int option =
+  if addr >=. mem_bot && addr <. mem_top then
+    Some (Int64.to_int (addr -. mem_bot))
+  else
+    None
+
 
 (* Your simulator should raise this exception if it tries to read from or
    store to an address not within the valid address space. *)
 exception X86lite_segfault
 
 (* Raise X86lite_segfault when addr is invalid. *)
-let map_addr_segfault (addr : quad) : int = failwith "map_addr_segfault not implemented"
+let map_addr_segfault (addr : quad) : int =
+  let idx = map_addr addr in
+  match idx with
+  | Some i -> i
+  | None -> raise X86lite_segfault
 
 (* Simulates one step of the machine:
    - fetch the instruction at %rip