頂層Makefile
# 頂層Makefile，負責聲明編譯標誌以及調用Makefile.build
CROSS_COMPILE = arm-linux-
AS = $(CROSS_COMPILE)as
LD = $(CROSS_COMPILE)ld
CC = $(CROSS_COMPILE)gcc
CPP = $(CC) -E
AR = $(CROSS_COMPILE)ar
NM = $(CROSS_COMPILE)nm
STRIP = $(CROSS_COMPILE)strip
OBJCOPY = $(CROSS_COMPILE)objcopy
OBJDUMP = $(CROSS_COMPILE)objdump
export AS LD CC CPP AR NM
export STRIP OBJCOPY OBJDUMP
CFLAGS := -Wall -O2 -g
CFLAGS += -I$(shell pwd)/include
LDFLAGS := -lm -lfreetype -lts
export CFLAGS LDFLAGS
TOPDIR := $(shell pwd)
export TOPDIR
obj-y += main.o
obj-y += draw/
obj-y += disp/
obj-y += font/
obj-y += encoding/
obj-y += input/
TARGET := dig_book
all :
make -C ./ -f $(TOPDIR)/Makefile.build
$(CC) $(LDFLAGS) -o $(TARGET) build-in.o
clean :
rm -f $(shell find -name "*.o")
rm -f $(TARGET)
distclean :
rm -f $(shell find -name "*.o")
rm -f $(shell find -name "*.d")
rm -f $(TARGET)
Makefile.build
# 本文件的最終目標
__build :
obj-y :=
subdir-y :=
# 引入各個Makefile中聲明的obj-y
include Makefile
# 在子目錄中調用Makefile.build
subdir-y += $(patsubst %/, %, $(filter %/, $(obj-y)))
cur_objs-y := $(filter-out %/, $(obj-y))
subdir_objs-y := $(foreach f, $(subdir-y), $(f)/build-in.o)
dep_files := $(foreach f, $(cur_objs-y), .$(f).d)
dep_files := $(wildcard $(dep_files))
ifneq ($(dep_files), )
include $(dep_files)
endif
__build : $(subdir-y) build-in.o
# 在這裏聲明僞目標，確認每次編譯都進入子目錄調用Makefile.build
.PHONY : $(subdir-y)
$(subdir-y) :
make -C $@ -f $(TOPDIR)/Makefile.build
build-in.o : $(cur_objs-y) $(subdir_objs-y)
$(LD) -r -o $@ $^
%.o : %.c
$(CC) $(CFLAGS) -Wp,-MD,[email protected] -c -o $@ $<
子目錄Makefile
obj-y += freetype.o
obj-y += gbk.o
obj-y += ascii.o
obj-y += font_manager.o
include 與 -include
使用“-include”當包含的文件不存在時，make將忽略此錯誤。
僞目標.PHONY作用
①防止源文件目錄下有同名文件，如“clean”
②優化，因爲僞目標一般都不是由文件生成，可以跳過文件搜索