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

bacnet-stack/include/config.h

@@ -47,7 +47,7 @@
 
 /* Enable the Gateway (Routing) functionality here, if desired. */
 #if !defined(BAC_ROUTING)
-#define BAC_ROUTING 0
+#define BAC_ROUTING 1
 #endif
 #if !defined(MAX_NUM_DEVICES)
 #if BAC_ROUTING

bacnet-stack/include/datalink.h

@@ -81,7 +81,11 @@
 #endif
 #define datalink_cleanup bip_cleanup
 #define datalink_get_broadcast_address bip_get_broadcast_address
+#if BAC_ROUTING
+#define datalink_get_my_address routed_get_my_address
+#else
 #define datalink_get_my_address bip_get_my_address
+#endif
 
 #else /* Ie, BACDL_ALL */
 #include "npdu.h"

bacnet-stack/include/device.h

@@ -319,10 +319,18 @@ extern "C" {
     	int idx );
     BACNET_ADDRESS * Get_Routed_Device_Address(
 		int idx );
-    bool Lookup_Routed_Device_Address( 
+    
+    void routed_get_my_address(
+        BACNET_ADDRESS * my_address);
+
+    bool Routed_Device_Address_Lookup( 
     		int idx, 
     		uint8_t address_len,        
     		uint8_t * mac_adress );
+    bool Routed_Device_GetNext( 
+    	    BACNET_ADDRESS * dest,
+    	    int * DNET_list,
+    		int * cursor );
     
     uint32_t Routed_Device_Index_To_Instance(
         unsigned index);