How to write a makefile both for a native compiler (g++ on Raspberry Pi), and for a crosscompiler (crosstool-ng)? - makefile

Question

I've just run into the following issue: I've got a Raspi 3B with a GNU toolchain I normally use to build my C++ project on the Raspi itself. As my project has grown quite large, I would now prefer to cross-build it on my Linux PC with crosstool-ng installed. What I need, though, is a makefile, which both works with the toolchain on the Raspi, and the crosstool. This has been my makefile so far:
CC=g++
CFLAGS=-std=c++11 -ggdb -Wall -Wmultichar
LDFLAGS=-L/usr/lib -L/usr/lib/arm-linux-gnueabihf
LIBRARIES=-lpthread -lkeystonecomm -lgps -lpigpio -lGeographic -lmk4 -lcsvparser -lasound -lespeak -lmpg123 -lout123
SRC=main.cpp vfd.cpp relay.cpp keypad.cpp receiver.cpp widgets.cpp tmc.cpp database.cpp sound.cpp
OBJECTS=main.o vfd.o relay.o keypad.o receiver.o widgets.o tmc.o database.o sound.o
EXEC=autoradio
$(EXEC) : $(OBJECTS)
$(CC) $(CFLAGS) $(OBJECTS) -o $(EXEC) $(LDFLAGS) $(LIBRARIES)
$(OBJECTS) : $(SRC)
$(CC) $(CFLAGS) -c $(SRC)
.PHONY: clean
clean:
rm -rf *.o $(EXEC)
The issue is the following: The crosscompiler is called arm-unknown-linux-gnueabi-g++, and the library paths are different. My goal, however, is to start the build process with a simple make command both on my Raspi, and on my host machine. Or will I have to use a configure script?
As I haven't found any useful tutorials on the Web, may anybody please help me. Thx.

Answer 1

OK, after consulting a few sources, I decided to implant a conditional into my makefile, which asks for the CPU environment variable. As Raspbian does not set it, I set the Raspi's architecture as a default. Et voilà, it works:
CPU?=armv7l
ifeq ($(CPU), armv7l)
CC=g++
else
CC=arm-unknown-linux-gnueabi-g++
endif
CFLAGS=-std=c++11 -ggdb -Wall -Wmultichar
ifeq ($(CPU), armv7l)
LDFLAGS=-L/usr/lib -L/usr/lib/arm-linux-gnueabihf
else
LDFLAGS=-L/usr/lib -L/opt/x-tools/arm-unknown-linux-gnueabi/lib
endif
LIBRARIES=-lpthread -lkeystonecomm -lgps -lpigpio -lGeographic -lmk4 -lcsvparser -lasound -lespeak -lmpg123 -lout123
SRC=main.cpp vfd.cpp relay.cpp keypad.cpp receiver.cpp widgets.cpp tmc.cpp database.cpp sound.cpp
OBJECTS=main.o vfd.o relay.o keypad.o receiver.o widgets.o tmc.o database.o sound.o
EXEC=autoradio
$(EXEC) : $(OBJECTS)
$(CC) $(CFLAGS) $(OBJECTS) -o $(EXEC) $(LDFLAGS) $(LIBRARIES)
$(OBJECTS) : $(SRC)
$(CC) $(CFLAGS) -c $(SRC)
.PHONY: clean
clean:
rm -rf *.o $(EXEC)