extract ipv4 into its own static library

CMakeLists.txt

@@ -5,6 +5,7 @@ add_subdirectory(w6300)
 add_subdirectory(debug_log)
 add_subdirectory(msgpack)
 add_subdirectory(eth)
+add_subdirectory(ipv4)
 
 add_library(limen STATIC
     src/arp.cpp
@@ -13,7 +14,6 @@ add_library(limen STATIC
     src/handlers.cpp
     src/icmp.cpp
     src/igmp.cpp
-    src/ipv4.cpp
     src/test_handlers.cpp
     src/udp.cpp
 )
@@ -30,6 +30,7 @@ target_link_libraries(limen PUBLIC
     debug_log
     msgpack
     eth
+    ipv4
     pico_stdlib
     pico_sha256
 )

ipv4/CMakeLists.txt

@@ -0,0 +1,11 @@
+add_library(ipv4 STATIC ipv4.cpp)
+
+target_include_directories(ipv4 PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+
+target_compile_options(ipv4 PRIVATE -Wall -Wextra -Wno-unused-parameter)
+
+target_link_libraries(ipv4 PUBLIC
+    util
+    eth
+    debug_log
+)