Followed Steve's good recommendation, and made routed_get_my_address() be a variant of datalink_get_my_address() just when routing is in use. Haven't done anything about the sending functions yet.

Renamed Lookup_Routed_Device_Address() as Routed_Device_Address_Lookup(), and replaced it in the routed npdu handler with a function that finds the "next" gateway or routed device, as per the destination address.  (Less tied to the specifics of the gw_device.c implementation.)
Fixed a few build warnings (eg, %zu for size_t arguments).
Until we improve the makefile system, I've enabled BAC_ROUTING in config.h

bacnet-stack/include/bacapp.h

@@ -197,10 +197,8 @@ extern "C" {
         unsigned max_apdu_len,
         BACNET_PROPERTY_ID property);
 
-#if PRINT_ENABLED
-#define BACAPP_PRINT_ENABLED
-#else
-#ifdef TEST
+#ifndef BACAPP_PRINT_ENABLED    
+#if PRINT_ENABLED || defined TEST
 #define BACAPP_PRINT_ENABLED
 #endif
 #endif