How to let avr-gcc output *.o to separate folder in Makefile with `%.o: %.c`? - gcc

As showed in first screenshot, my ideal AVR project structure is that:
*.o, *.elf and *.hex files are in build folder.
PomoScheler.c and pinDefines.h as main files are in root folder, while other *.c and *.h are in src folder.
But *.o are always generated at the same folder as *.c like showed in second screenshot, no matter how.
(I attached my endeavors and whole Makefile below the screenshots)
Firstly, I tried build/ before $#, in vain. The terminal still the same.
# My first Makefile endeavor
%.o: %.c $(HEADERS)
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o build/$#
# Terminal command generated by Makefile (Look at the end: *.o path still same as *.c)
avr-gcc -Os -g -std=gnu99 -Wall -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -ffunction-sections -fdata-sections -DF_CPU=1000000UL -DBAUD=9600UL -I. -I~/Developer/bin/avr8-gnu-toolchain-darwin_x86_64/avr/include -mmcu=atmega328p -c -o src/RotaryEncoder.o src/RotaryEncoder.c
Secondly, I tried to add mv $# build to explicitly move it to build folder. But nothing happened. Even echo are not displayed in Terminal.
# My second Makefile endeavor
%.o: %.c $(HEADERS)
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $#
mv $# build
echo ---------Hello---------
Thirdly, I delete $(HEADERS) and replace $< with $^ just to have a try. The mv is executed. But it cannot find *.o file this time even though I have VPATH = src:build in Makefile.
# My third Makefile endeavor
%.o: %.c
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $^ -o $#
mv $# build
# Terminal error
Assembler messages:
Fatal error: can't create build/src/RotaryEncoder.o: No such file or directory
And my whole Makefile is here. Please help me out.
# My whole Makefile
MCU = atmega328p
F_CPU = 1000000UL
BAUD = 9600UL
LIBDIR = ~/Developer/bin/avr8-gnu-toolchain-darwin_x86_64/avr/include
PROGRAMMER_TYPE = usbtiny
PROGRAMMER_ARGS =
CC = avr-gcc
OBJCOPY = avr-objcopy
OBJDUMP = avr-objdump
AVRSIZE = avr-size
AVRDUDE = avrdude
##########------------------------------------------------------##########
VPATH = ./src:./build
TARGET = $(lastword $(subst /, ,$(CURDIR)))
SOURCES=$(wildcard *.c src/*.c $(LIBDIR)/*.c)
OBJECTS=$(SOURCES:.c=.o)
HEADERS=$(SOURCES:.c=.h)
CPPFLAGS = -DF_CPU=$(F_CPU) -DBAUD=$(BAUD) -I. -I$(LIBDIR)
CFLAGS = -Os -g -std=gnu99 -Wall
CFLAGS += -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums
CFLAGS += -ffunction-sections -fdata-sections
LDFLAGS = -Wl,-Map,build/$(TARGET).map
LDFLAGS += -Wl,--gc-sections
TARGET_ARCH = -mmcu=$(MCU)
%.o: %.c $(HEADERS)
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o build/$#
$(TARGET).elf: $(OBJECTS)
$(CC) $(LDFLAGS) $(TARGET_ARCH) $^ $(LDLIBS) -o build/$#
%.hex: %.elf
$(OBJCOPY) -j .text -j .data -O ihex build/$< build/$#
all: $(TARGET).hex
size: $(TARGET).elf
$(AVRSIZE) -C --mcu=$(MCU) $(TARGET).elf
clean:
rm -f $(TARGET).elf $(TARGET).hex $(TARGET).obj \
$(TARGET).o $(TARGET).d $(TARGET).eep $(TARGET).lst \
$(TARGET).lss $(TARGET).sym $(TARGET).map $(TARGET)~ \
$(TARGET).eeprom
flash: $(TARGET).hex
$(AVRDUDE) -c $(PROGRAMMER_TYPE) -p $(MCU) $(PROGRAMMER_ARGS) -U flash:w:$<

This is clearly not right:
OBJECTS = $(SOURCES:.c=.o)
because the object files you want to create are not foo.o etc. which is what this will expand to; the object files are build/foo.o etc. So this has to be:
OBJECTS = $(patsubst %.c,build/%.o)
All of your attempts to trick make by telling it your recipe will build one target (foo.o) but actually building a totally different target (build/foo.o) are doomed to fail, regardless of whether you have the compiler do it directly, you use mv, or any other method.
If you just tell make what your recipe actually does, you will have a much simpler time of it:
build/%.o: %.c
mkdir -p $(#D)
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $^ -o $#
Probably you have similar issues with the other rules that you want to put into other directories.
You can't do this by trying to hide it from make. Make has to know where the files actually are.
BTW, VPATH cannot help here. VPATH is for finding source files, it cannot be used for finding generated files. So you could use VPATH to find your .c files but not your .o files.

Related

Why does my Makefile with pattern rules not create debugging symbols for main?

I am using this auto-generated Makefile with pattern rules, that I oviously do not understand yet. I want to create debuggins symbols and then debug main, but it doesn't work. There is a -g flag. Adding $(LDFLAGS) statement above after $(ODIR) does not print one as expcted.
IDIR =./include
CC=g++
CFLAGS = -I$(IDIR)
LDFLAGS = -g
ODIR=./
LIBS=
_OBJ = main.o
OBJ = $(patsubst %,$(ODIR)/%,$(_OBJ))
$(ODIR)/%.o: %.c
$(CC) -c -o $# $< $(CFLAGS)
main: $(OBJ)
$(CC) $(LDFLAGS) -o $# $^ $(CFLAGS) $(LIBS)
.PHONY: clean
clean:
rm -f $(ODIR)/*.o
This is the terminal output
g++ -c -o Source.o Source.cpp
g++ -g -o Source Source.o -I./include
Your sources are C++ (.cpp) but your Makefile contains explicit instructions for building C files. Make is therefore falling back to its built in implicit rules.
Also note that by convention those rules use $(CXX) to refer to the C++ compiler, with $(CXXFLAGS) replacing $(CFLAGS), and the -I flag belongs in $(CPPFLAGS):
IDIR =./include
CPPFLAGS = -I$(IDIR)
CXXFLAGS = -g
ODIR=.
LIBS=
_OBJ = main.o
OBJ = $(patsubst %,$(ODIR)/%,$(_OBJ))
$(ODIR)/%.o: %.cpp
$(CXX) -c -o $# $(CPPFLAGS) $(CXXFLAGS) $<
main: $(OBJ)
$(CXX) $(CXXFLAGS) $(LDFLAGS) -o $# $^ $(LIBS)
.PHONY: clean
clean:
rm -f $(OBJ)
If you were to do away with the ODIR handling and use the conventional variable names you could do without the explicit .o: .cpp rule altogether.

How to compile source objects into another directory and then build an executable?

Good day. I am in a directory, where is Makefile and folders src and bin. How can I compile object files into bin folder and then build an executable file?
I read some instructions and added $(BIN) before %.o, but it didn't helped, object files appear in folder with makefile. Where is the problem?
CC = arm-linux-gnueabihf-gcc
CXX = arm-linux-gnueabihf-g++
CPPFLAGS = -I .
CFLAGS =-g -std=gnu99 -O1 -Wall
CXXFLAGS = -g -std=gnu++11 -O1 -Wall
LDFLAGS = -lrt -lpthread
SRCDIR = src
BIN = bin
SOURCES = $(wildcard $(SRCDIR)/*.cpp) $(wildcard $(SRCDIR)/*.c)*
...
OBJECTS += $(filter %.o,$(SOURCES:%.c=%.o))
OBJECTS += $(filter %.o,$(SOURCES:%.cpp=%.o))
#$(warning OBJECTS=$(OBJECTS))
ifeq ($(filter %.cpp,$(SOURCES)),)
LINKER = $(CC)
LDFLAGS += $(CFLAGS) $(CPPFLAGS)
else
LINKER = $(CXX)
LDFLAGS += $(CXXFLAGS) $(CPPFLAGS)
endif
$(BIN)/%.o:%.c
$(CC) $(CFLAGS) -c $<
$(BIN)/%.o:%.cpp
$(CXX) $(CXXFLAGS) -c $<
all: $(TARGET_EXE)
$(TARGET_EXE): $(OBJECTS)
$(LINKER) $(LDFLAGS) -L. $^ -o $#
.PHONY : dep all run copy-executable debug
dep: depend
depend: $(SOURCES) *.h
echo '# autogenerat`enter code here`ed dependencies' > depend
ifneq ($(filter %.c,$(SOURCES)),)
$(CC) $(CFLAGS) $(CPPFLAGS) -w -E -M $(filter %.c,$(SOURCES)) \
>> depend
endif
ifneq ($(filter %.cpp,$(SOURCES)),)
$(CXX) $(CXXFLAGS) $(CPPFLAGS) -w -E -M $(filter %.cpp,$(SOURCES)) \
>> depend
endif
clean:
rm -f *.o *.a $(OBJECTS) $(TARGET_EXE) connect.gdb depend
...
It's not clear to me how this makefile can works as well as it does, given that you haven't told it where to find the source files (unless you do so in one of the elided sections).
In these rules:
$(BIN)/%.o:%.c
$(CC) $(CFLAGS) -c $<
$(BIN)/%.o:%.cpp
$(CXX) $(CXXFLAGS) -c $<
you tell the compiler to build object files, but you don't specify where to build them, and the default is to build them in the working directory. You can override that with the -o option:
$(BIN)/%.o:%.c
$(CC) $(CFLAGS) -c $< -o $#
$(BIN)/%.o:%.cpp
$(CXX) $(CXXFLAGS) -c $< -o $#
Once you have the object files where you want them (bin/), you must ensure that the linking rule:
$(TARGET_EXE):$(OBJECTS)
$(LINKER) $(LDFLAGS) -L. $^ -o $#
can find them. The best way to do that is to ensure that OBJECTS contains the correct paths to the object files. I'm not sure how to advise you to do that, since from the look of your makefile that variable might not contain what you think it does.
EDIT:
Let's take this in stages.
Suppose we have on source file, src/foo.c. What we want is:
src/foo.c -> bin/foo.o
bin/foo.o -> foo
This requires two rules, which we can write like this:
$(BIN)/%.o: src/%.c
$(CC) $(CFLAGS) -c $< -o $#
$(TARGET_EXE): bin/foo.o
$(LINKER) $(LDFLAGS) -L. $^ -o $#
We actually have many source files, some of which are C++ files. So we must have a rule for them:
$(BIN)/%.o: src/%.cpp
$(CXX) $(CXXFLAGS) -c $< -o $#
and construct a longer list of objects:
OBJECTS := bin/foo.o bin/bar.o bin/baz.o bin/quartz.o...
$(TARGET_EXE): $(OBJECTS)
$(LINKER) $(LDFLAGS) -L. $^ -o $#
(Mixing C and C++ seems unhealthy to me, but never mind.)
And how do we construct that list of objects? We must start with the list of sources which wildcard can produce:
SRC := src
C_SOURCES := $(wildcard $(SRC/*.c)
# this is src/foo.c src/bar.c
SRC := src
CPP_SOURCES := $(wildcard $(SRC/*.cpp)
# this is src/baz.cpp src/quartz.cpp
and then convert them to the object file names we actually want:
BIN := bin
OBJECTS := $(patsubst $(SRC)/%.cpp,$(BIN)/%.o, $(CPP_SOURCES))
OBJECTS += $(patsubst $(SRC)/%.c,$(BIN)/%.o, $(C_SOURCES))
# this is bin/foo.o bin/bar.o bin/baz.o bin/quartz.o
That should give you the effect you want, and if you understand it you will understan why your old makefile did not.

Makefile - Compile Single Objects in different directory

I have been combing the web and I can't figure out the right way to get this to work. Just trying to create a simple Makefile which takes my source and only builds the changed files. I need all the .o files to be put in the same output folder. I currently have everything working except that if I change one file the whole thing rebuilds. For example, if I change main.c it will compile EOL.c as well. However if nothing changes it says nothing needs to be done.
NAME=Program
CC=arm-none-eabi-gcc
CFLAGS=-c -Wall -O0 -std=c99 \
-nostartfiles --specs=nano.specs \
-mthumb -fmessage-length=0 \
-fsigned-char -ffunction-sections \
-fdata-sections -mcpu=cortex-m0
BID?=_DEV
DEFINES= -DPROD -DBLD_ID=\"$(BID)\"
LDFLAGS= -nostartfiles
INCLUDES= -ISrc/App/Include -ISrc/Device/CMSIS/Include
SOURCES= Src/main.c Src/App/Source/Application.c Src/App/Source/EOL.c Src/Svc/Source/TimerManager.c
OBJECTS=$(OBJECTS1:.c=.o)
OBJECTS1=$(SOURCES:.S=.o)
OFILES1=$(notdir ${OBJECTS})
OFILES=$(addprefix $(OBJDIR)/,$(OFILES1))
OBJDIR=Output
.PHONY: all rebuild clean
all: $(OBJDIR) $(SOURCES) $(OBJDIR)/$(NAME).hex
%.hex: %.elf
arm-none-eabi-objcopy -O ihex $< $#
%elf: $(OBJECTS)
$(CC) $(LDFLAGS) $(OFILES) -o $#
rebuild: clean all
.SECONDARY:
.c.o:
$(CC) $(CFLAGS) $(DEFINES) $(INCLUDES) $< -o $(OBJDIR)/$(notdir $#)
.S.o:
$(CC) $(CFLAGS) $(DEFINES) $(INCLUDES) $< -o $(OBJDIR)/$(notdir $#)
$(OBJDIR):
mkdir $(OBJDIR)
clean:
rm -f $(OBJDIR)/*.o $(OBJDIR)/*.elf $(OBJDIR)/*.hex $(OBJDIR)/*.bin
There are several problems with this makefile. Basically you have rules whose targets are not the files they actually produce, and a rule whose prerequisites are not the files it actually needs.
Suppose you have modified Src/main.c and try to rebuild Output/Program.elf using this rule:
%elf: $(OBJECTS)
$(CC) $(LDFLAGS) $(OFILES) -o $#
The prerequisites ($(OBJECTS)) are actually Src/main.o Src/App/Source/EOL.o and so on. These files do not exist -- they never exist -- but there is a rule for them:
.c.o:
$(CC) $(CFLAGS) $(DEFINES) $(INCLUDES) $< -o $(OBJDIR)/$(notdir $#)
Make sees that Src/main.o depends on Src/main.c and must therefore be rebuilt, as must Output/Program.elf. So it invokes this rule -- which actually builds Output/main.o. But the elf rule demands all of the (imaginary) object files, so all of the sources must be recompiled-- into object files that already exist and are not out of date, but which Make wasn't paying attention to.
The first thing to do is fix the object rules, but there's a problem: although the rules are flawed, they have the advantage of helping Make to find the corresponding source files (before misusing them), like this:
Src/App/Source/EOL.o: Src/App/Source/EOL.c
...
How can we tell Make where to find the source file corresponding to Output/EOL.o? There's more than one way, but a good way is by using vpath:
vpath %.c Src/App/Source
Output/EOL.o: EOL.c
...
All we have to do is create a list of source directories, pass it to vpath, and modify the pattern rule:
SRCDIRS := $(dir $(SOURCES))
vpath %.c $(SRCDIRS)
$(OBJDIR)/%.o: %.c
$(CC) $(CFLAGS) $(DEFINES) $(INCLUDES) $< -o $#
(The .S.o rule can be fixed the same way.)
Then modify the elf rule to name -- and use -- its real prerequisites:
%elf: $(OFILES)
$(CC) $(LDFLAGS) $^ -o $#

gcc cannot specify -o with -c or -S with Multiple files

Whenever I am trying to build something like this in my Makefile -
gcc -o main.o -IStarterWare_Files -c main.c StarterWare_Files/test.h StarterWare_Files/add.h
It throws me error that gcc: cannot specify -o with -c or -S with multiple files. Basically I want my makefile to build the target again if I change for example some macro in one of my header files. My current Makefile is -
EXE = nextgenrsm
CC = gcc
LIBS = StarterWare_Files/
CPPFLAGS = _IStarterWare_Files/
MAIN_OBS = $(patsubst %.c,%.o,$(wildcard *.c))
LIB_OBS = $(patsubst %.c,%.o,$(wildcard StarterWare_Files/*.c))
all: $(EXE)
$(EXE): $(MAIN_OBS) $(LIB_OBS)
$(CC) -o $# $(LDFLAGS) $(MAIN_OBS) $(LIB_OBS) $(LDLIBS)
%.o: %.c
$(CC) -o $# -MD -MP $(CPPFLAGS) $(CFLAGS) -c $^
ALL_DEPS = $(patsubst %.o,%.d,$(MAIN_OBS), $(LIB_OBS))
-include $(ALL_DEPS)
clean:
rm -f $(LIB_OBS) $(EXE) $(MAIN_OBS) $(ALL_DEPS)
.PHONY: all clean
I can't figure out what changes to make to build my executable again if one of the header files is modified. I don't want to do make clean and make again.
The way the automake system handles this is to not use %.o: %.c but instead list the C file and all of the headers in the C file.
So for example:
main.o: main.c StarterWare_Files/test.h StarterWare_Files/add.h
$(CC) -o $# -MD -MP $(CPPFLAGS) $(CFLAGS) -c $^
See makedepends for a tool that will read C files and figure out the make dependencies.

Making a better Makefile

so I learned what a Makefile was some time ago, created a template Makefile and all I do is copy and alter the same file for every program I'm doing. I changed it a few times, but it's still a very crude Makefile. How should I improve it? This is an example of my current version:
CC = g++
CFLAGS = -std=gnu++0x -m64 -O3 -Wall
IFLAGS = -I/usr/include/igraph
LFLAGS = -ligraph -lgsl -lgslcblas -lm
DFLAGS = -g -pg
# make all
all: run test
# make a fresh compilation from scratch
fresh: clean test
#makes the final executable binary
run: main.o foo1.o foo2.o
$(CC) $(CFLAGS) $(LFLAGS) $^ -o $#
#makes the test executable with debugging and profiling tags
test: test.o foo1.o foo2.o
$(CC) $(DFLAGS) $(CFLAGS) $(LFLAGS) $^ -o $#
#makes teste.o
teste.o: teste.cpp
$(CC) $(CFLAGS) $(IFLAGS) -c $^ -o $#
#makes main.o
main.o: main.cpp
$(CC) $(CFLAGS) $(IFLAGS) -c $^ -o $#
#file foo1
foo1.o: foo1.cpp
$(CC) $(CFLAGS) $(IFLAGS) -c $^ -o $#
#file foo2
foo2.o: foo2.cpp
$(CC) $(CFLAGS) $(IFLAGS) -c $^ -o $#
clean: clean-test clean-o clean-annoying
clean-test:
rm test-rfv
clean-o:
rm *.o -rfv
clean-annoying:
rm *~ -rfv
Just by visually comparing with other makefiles I saw around in the web, this seems to be not a very bright Makefile. I don't know how they work, but I can see there's significantly less boilerplate and more generic code in them.
Can this can be made better, safer, and easier to particularize for each project?
You don't want to name specific files in a makefile if you can get away with it, and 99% of the time you can. This page shows how to develop a very general makefile. The following is my own makefile, based on that page's info:
SHELL := bash
PROG := pathed.exe
OUTDIRS := bin/debug bin/rel obj/debug obj/rel
PROG_REL := bin/rel/$(PROG)
PROG_DEBUG := bin/debug/$(PROG)
SRCFILES := $(wildcard src/*.cpp)
OBJFILES_REL := $(patsubst src/%.cpp,obj/rel/%.o,$(SRCFILES))
OBJFILES_DEBUG := $(patsubst src/%.cpp,obj/debug/%.o,$(SRCFILES))
DEPFILES := $(patsubst src/%.cpp,obj/%.d,$(SRCFILES))
CFLAGS := -Iinc -Wall -Wextra -MMD -MP
DBFLAGS := -g
RELFLAGS :=
CC := g++
.PHONY: default all testmake debug release clean dirs
default: debug
all: dirs clean debug release
dirs:
#mkdir -p $(OUTDIRS)
debug: $(PROG_DEBUG)
release: $(PROG_REL)
testmake:
#echo OBJFILES_REL = $(OBJFILES_REL)
#echo OBJFILES_DEBUG = $(OBJFILES_DEBUG)
#echo SRCFILES = $(SRCFILES)
#echo DEPFILES = $(DEPFILES)
clean:
rm -f $(OBJFILES_REL) $(OBJFILES_DEBUG) $(DEPFILES) $(PROG)
$(PROG_REL): $(OBJFILES_REL)
$(CC) $(OBJFILES_REL) -o $(PROG_REL)
strip $(PROG_REL)
#echo "---- created release binary ----"
$(PROG_DEBUG): $(OBJFILES_DEBUG)
$(CC) $(OBJFILES_DEBUG) -o $(PROG_DEBUG)
#echo "---- created debug binary ----"
-include $(DEPFILES)
obj/rel/%.o: src/%.cpp
$(CC) $(RELFLAGS) $(CFLAGS) -MF $(patsubst obj/rel/%.o, obj/%.d,$#) -c $< -o $#
obj/debug/%.o: src/%.cpp
$(CC) $(DBFLAGS) $(CFLAGS) -MF $(patsubst obj/debug/%.o, obj/%.d,$#) -c $< -o $#
Do NOT use CC for the C++ compiler. The standard convention is that CC is the C compiler, CXX is the C++ compiler. CFLAGS are flags for the C compiler, CXXFLAGS are flags for the C++ compiler, and CPPFLAGS are flags for the pre-processor (eg, -I or -D flags). Use LDFLAGS for -L flags to the linker, and LDLIBS (or LOADLIBES) for -l flags.
Using the standard conventions is good not just because it makes things easier for others to understand, but also because it allows you to take advantage of implicit rules. If make needs to make a .o file from a .c file and you have not provided a rule, it will use a standard rule and honor the settings of CC, CFLAGS, and CPPFLAGS. If CC is a C++ compiler, things will probably not work.

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