Implement hot reloading

CMakeLists.txt

@@ -5,6 +5,7 @@ project(epec-mcu-emulator LANGUAGES C)
 option(WERROR "Treat warnings as errors" OFF)
 option(UBSAN "Enable undefined behaviour sanitizer" OFF)
 option(PERFMON "Monitor performance of game code" ON)
+option(HOTRELOAD "Enable hot reloading of game code" OFF)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
@@ -19,6 +20,9 @@ macro(set_default_target_options target)
 	target_compile_options(${target} PRIVATE -fsanitize=undefined)
 	target_link_options(${target} PRIVATE -fsanitize=undefined)
   endif()
+  if(${HOTRELOAD})
+	target_compile_definitions(engine PRIVATE HOTRELOAD)
+  endif()
 endmacro()
 
 add_custom_target(format
@@ -40,3 +44,9 @@ find_package(SDL2_image REQUIRED)
 
 add_subdirectory(engine)
 add_subdirectory(game)
+
+# Really this should be in engine/CMakeLists.txt, but it has to go
+# after the declaration of the game target.
+if(${HOTRELOAD})
+  target_compile_definitions(engine PRIVATE GAMELIB=\"$<TARGET_FILE:game>\")
+endif()