DIR_FILT = filt/ SOURCES_FILT += filt/filt_5th.c filt/filt_delay.c OBJECTS_FILT += $(SOURCES_FILT:.c=.o) LDFLAGS += LDFLAGS_BSD += OBJECTS_DIR_FILT += $(subst $(DIR_FILT),$(BUILD_DIR)$(DIR_FILT),$(OBJECTS_FILT)) OBJECTS += $(OBJECTS_FILT) OBJECTS_FINAL += $(OBJECTS_DIR_FILT)