fixed makefile

Author: JasonKlm

makefile

@@ -22,22 +22,22 @@ LDFLAGS    := $(MCU_FLAGS) -T$(LDSCRIPT) -Wl,-Map=$(BUILD_DIR)/$(PROJECT).map,--
 C_SOURCES  := $(wildcard $(SRC_DIR)/*.c)
 OBJ_FILES  := $(patsubst $(SRC_DIR)/%.c, $(BUILD_DIR)/%.o, $(C_SOURCES))
 
-all: $(BUILD_DIR)/$(PROJECT).elf
+all: $(BUILD_DIR) $(BUILD_DIR)/$(PROJECT).elf
 
-$(BUILD_DIR)/%.o: $(SRC_DIR)/%.c | prepare_build
+$(BUILD_DIR):
+	mkdir -p $(BUILD_DIR)
+
+$(BUILD_DIR)/%.o: $(SRC_DIR)/%.c | $(BUILD_DIR)
 	@echo "[CC]  $<"
 	mkdir -p $(dir $@)
 	$(CC) $(CFLAGS) $(CDEFS) $(CINCLUDES) -c $< -o $@
 
-$(BUILD_DIR)/$(PROJECT).elf: $(OBJ_FILES)
+$(BUILD_DIR)/$(PROJECT).elf: $(OBJ_FILES) | $(BUILD_DIR)
 	@echo "[LD]  $@"
 	$(CC) $^ $(LDFLAGS) -o $@
 	$(SZ) $@
 
-prepare_build:
-	mkdir -p $(BUILD_DIR)
-
 clean:
 	rm -rf $(BUILD_DIR)
 
-.PHONY: all clean prepare_build
+.PHONY: all clean