Adjust Makefile to only recompile files if they have changed - c

Question

I have a question regarding my Makefile. The Makefile intends to compile C files containing code for a STM8 µC using the Cosmic compiler. The problem is that everytime I invoke the build target, all available source file are getting recompiled without any change. I'm really new in the field of Makefiles and I have no idea how to fix it.
The second questions is related to the two targets "%.o: src/%.c" and %.o: src/stm8/%.c. They do exactly the same and I would prefer a generic one that is able to deal with all subdirectories within the src folder. With this solution it ist required to add an additional rule for each subfolder of the src folder
#***************PROJECT INFORMATIONS****************
PROJECT_NAME = stm8template
MODULES = stm8
#****************SET BUILD MODE*********************
ifeq ($(MODE), )
MODE=Debug
endif
#***************DIRECTORY INFORMATION***************
SRCDIR = src
INCLUDES = includes
OUTPUT_DIR = bin/$(MODE)
#**************HELPER FUNCTIONS*********************
rwildcard=$(wildcard $1$2) $(foreach d,$(wildcard $1*),$(call rwildcard,$d/,$2))
#***************FILE SPECIFICATIONS***************
SOURCE_FILES = $(foreach d, $(call rwildcard,$(SRCDIR),*.c), $(notdir $d))
OBJECT_FILES = $(patsubst %.c, %.o, $(SOURCE_FILES))
HEADER_FILES = $(wildcard $(INCLUDES)/*.h) $(wildcard $(INCLUDES)/**/*.h)
INCLUDE_DIRS_PARAM=$(foreach d, $(MODULES), -iincludes/$d) -iincludes -iC:\Hstm8
#***************COMPILER INFORMATIONS***************
CC = cxstm8
LIBS = -l +mods0
ifeq ("$(MODE)","Debug")
CFLAGS = $(INCLUDE_DIRS_PARAM) -cl$(OUTPUT_DIR) -co$(OUTPUT_DIR) -pxp -no -pp +debug
else
CFLAGS = $(INCLUDE_DIRS_PARAM) -cl$(OUTPUT_DIR) -co$(OUTPUT_DIR) -pxp -no -pp
endif
#***************LINKER INFORMATIONS***************
LINKFILE=$(OUTPUT_DIR)\$(PROJECT_NAME).lkf
OUTFILE=$(PROJECT_NAME)
LFLAGS = -lC:\Lib
#*************FLASHER CONFIGURATIONS***************
FLASHER_PATH="C:\Program Files (x86)\STMicroelectronics\st_toolset\stvp\STVP_CmdLine.exe"
DEVICE=STM8S105x6
PORT=USB
PROG_MODE=SWIM
BOARD_NAME=ST-LINK
FLASHER_PARAM = -no_loop
#***************BUILT TARGETS***************
all: build run
%.o: src/%.c
$(info ********** Compile $< ***********)
$(CC) $(CFLAGS) $(LIBS) $<
%.o: src/stm8/%.c
$(info ********** Compile $< ***********)
$(CC) $(CFLAGS) $(LIBS) $<
build: $(OBJECT_FILES)
$(info ********** Build the Application ***********)
clnk -m $(OUTPUT_DIR)\$(OUTFILE).map -o $(OUTPUT_DIR)\$(OUTFILE).sm8 $(LINKFILE)
cvdwarf $(OUTPUT_DIR)\$(OUTFILE).sm8
chex -o $(OUTPUT_DIR)\$(OUTFILE).s19 $(OUTPUT_DIR)\$(OUTFILE).sm8
run:
$(info ********** Flashing the Application ***********)
$(FLASHER_PATH) -BoardName=$(BOARD_NAME) -Device=$(DEVICE) -Port=$(PORT) -ProgMode=$(PROG_MODE) -FileProg="$(OUTPUT_DIR)\$(OUTFILE).s19" $(FLASHER_PARAM)

Answer 1

The build target never gets created, so the commands after it are executed every time you run make (or make all or make build), so the program is linked each time.
Change your build target so that it is phony:
.PHONY: build clean
and so that it depends on the program, not the object files:
build: $(OUTPUT_DIR)\$(OUTFILE).sm8
and then have a rule (recipe) that builds the program if the object files are more recent:
$(OUTPUT_DIR)\$(OUTFILE).sm8: $(OBJECT_FILES)
$(info ********** Build the Application ***********)
clnk -m $(OUTPUT_DIR)\$(OUTFILE).map -o $(OUTPUT_DIR)\$(OUTFILE).sm8 $(LINKFILE)
cvdwarf $(OUTPUT_DIR)\$(OUTFILE).sm8
chex -o $(OUTPUT_DIR)\$(OUTFILE).s19 $(OUTPUT_DIR)\$(OUTFILE).sm8
It isn't 100% clear to me that I chose the correct suffix for the program. I would also create series of macros to avoid the repetition I see:
OUTFILE.sm8 = $(OUTPUT_DIR)\$(OUTFILE).sm8
OUTFILE.s19 = $(OUTPUT_DIR)\$(OUTFILE).s19
OUTFILE.map = $(OUTPUT_DIR)\$(OUTFILE).map
build: $(OUTFILE.sm8)
$(OUTFILE.sm8): $(OBJECT_FILES)
$(info ********** Build the Application ***********)
clnk -m $(OUTFILE.map) -o $(OUTFILE.sm8) $(LINKFILE)
cvdwarf $(OUTFILE.sm8)
chex -o $(OUTFILE.s19) $(OUTFILE.sm8)
Also, since I work on Unix mostly, I'd use / instead of \, but that's a minor detail.

Answer 2

Update:
Thank you all for your help. I changed the Makefile in the way shown below. The second problem is now fixed but the first problem still remains.
Every time the build rule is invoked all .c files are recompiled. Compiling only the changed files is the main purpose/benefit of using make, I thought. So something is wrong but unfortunately I don't find the mistake.
#***************PROJECT INFORMATIONS****************
PROJECT_NAME = stm8template
MODULES = stm8
#****************SET BUILD MODE*********************
ifeq ($(MODE), )
MODE=Debug
endif
#***************DIRECTORY INFORMATION***************
SRCDIR = src
INCLUDES = includes
#**************HELPER FUNCTIONS*********************
rwildcard=$(wildcard $1$2) $(foreach d,$(wildcard $1*),$(call rwildcard,$d/,$2))
#***************FILE SPECIFICATIONS***************
SOURCE_FILES = $(foreach d, $(call rwildcard,$(SRCDIR),*.c), $(notdir $d))
OBJECT_FILES = $(patsubst %.c, %.o, $(call rwildcard,$(SRCDIR),*.c))
HEADER_FILES = $(wildcard $(INCLUDES)/*.h) $(wildcard $(INCLUDES)/**/*.h)
INCLUDE_DIRS_PARAM=$(foreach d, $(MODULES), -iincludes/$d) -iincludes -iC:\Hstm8
#***************COMPILER INFORMATIONS***************
CC = cxstm8
LIBS = -l +mods0
ifeq ("$(MODE)","Debug")
CFLAGS = $(INCLUDE_DIRS_PARAM) -cl$(OUTPUT_DIR) -co$(OUTPUT_DIR) -pxp -no -pp +debug
else
CFLAGS = $(INCLUDE_DIRS_PARAM) -cl$(OUTPUT_DIR) -co$(OUTPUT_DIR) -pxp -no -pp
endif
#***************LINKER INFORMATIONS***************
LINKFILE=$(OUTPUT_DIR)\$(PROJECT_NAME).lkf
LFLAGS = -LC:\Lib
#*******************OUTPUT FILES********************
OUTPUT_DIR = bin/$(MODE)
OUTFILE=$(PROJECT_NAME)
OUTFILE.sm8 = $(OUTPUT_DIR)\$(OUTFILE).sm8
OUTFILE.s19 = $(OUTPUT_DIR)\$(OUTFILE).s19
OUTFILE.map = $(OUTPUT_DIR)\$(OUTFILE).map
TARGET_FILE=$(OUTPUT_DIR)\$(PROJECT_NAME).elf
#*************FLASHER CONFIGURATIONS***************
FLASHER_PATH="C:\Program Files (x86)\STMicroelectronics\st_toolset\stvp\STVP_CmdLine.exe"
DEVICE := STM8S105x6
PORT=USB
PROG_MODE=SWIM
BOARD_NAME=ST-LINK
FLASHER_PARAM = -no_loop
#***************BUILT TARGETS***************
.PHONY: all run build clean
all: build run
%.o: %.c
$(info ********** Compile $< ***********)
$(CC) $(CFLAGS) $(LIBS) $<
build: $(OUTPUT_DIR)\$(PROJECT_NAME).elf
$(TARGET_FILE): $(OBJECT_FILES)
$(info ********** Build the Application ***********)
clnk -m $(OUTFILE.map) -o $(OUTFILE.sm8) $(LINKFILE)
cvdwarf $(OUTFILE.sm8)
chex -o $(OUTFILE.s19) $(OUTFILE.sm8)
run:
$(info ********** Flashing the Application ***********)
$(FLASHER_PATH) -BoardName=$(BOARD_NAME) -Device=$(DEVICE) -Port=$(PORT) -ProgMode=$(PROG_MODE) -FileProg="$(OUTPUT_DIR)\$(OUTFILE).s19" $(FLASHER_PARAM)