Refactor Makefile for compatibility with Docker enviroment and better

AVR dependency management

src/Makefile

@@ -4,18 +4,84 @@ MCU = atmega328p
 F_CPU = 16000000UL
 PROGRAMMER = arduino
 PORT ?= /dev/ttyACM0
+BAUD = 115200
+
+ARDUINO_INSTALL_PATH = /usr/share/arduino
+ARDUINO_CORE_PATH = $(ARDUINO_INSTALL_PATH)/hardware/arduino/avr/cores/arduino
+ARDUINO_VARIANT_PATH = $(ARDUINO_INSTALL_PATH)/hardware/arduino/avr/variants/standard
 
 CC = avr-gcc
-LD = avr-ld
+CXX = avr-g++
+LD = $(CXX) # Use C++ linker
 OC = avr-objcopy
 AD = avrdude
-CFLAGS = -Wall -Os -DF_CPU=$(F_CPU) -mmcu=$(MCU)
+AR = avr-ar
+RM = rm -f
 
-SRCS = main.c moisture.cpp
+BUILD_DIR = build
+OBJ_DIR = $(BUILD_DIR)/obj
+CORE_DIR = $(BUILD_DIR)/core
+
+
+CFLAGS = -Wall -Os -DF_CPU=$(F_CPU) -mmcu=$(MCU) -I$(ARDUINO_CORE_PATH) -I$(ARDUINO_VARIANT_PATH) -I.
+CXXFLAGS = $(CFLAGS) -fno-exceptions -fpermissive
+
+LDFLAGS = -Wall -Os -mmcu=$(MCU) -Wl,--gc-sections
+LIBS = -lm
+
+SRCS_CPP = main.cpp moisture.cpp
 HDRS = moisture.h config.h
-OBJS = main.o moisture.o config.o
+OBJS = $(addprefix $(OBJ_DIR)/, $(SRCS_CPP:.cpp=.o))
+
+CORE_C_SRCS = \
+	wiring_analog.c \
+	wiring_digital.c
+
+CORE_CPP_SRCS = \
+	abi.cpp \
+	new.cpp \
+	Print.cpp \
+	Stream.cpp \
+	HardwareSerial.cpp
+
+CORE_SRCS = $(addprefix $(ARDUINO_CORE_PATH)/, $(CORE_C_SRCS) $(CORE_CPP_SRCS))
+CORE_OBJS = $(patsubst $(ARDUINO_CORE_PATH)/%.c,$(CORE_DIR)/%.o,$(filter %.c,$(CORE_SRCS))) \
+            $(patsubst $(ARDUINO_CORE_PATH)/%.cpp,$(CORE_DIR)/%.o,$(filter %.cpp,$(CORE_SRCS)))
+
+CORE_LIB = $(BUILD_DIR)/libcore.a
+
 EXEC = moisture
+ELF_TARGET = $(BUILD_DIR)/$(EXEC).elf
+TARGET = $(BUILD_DIR)/$(EXEC).hex
 
-TARGET = moisture.hex
+all: $(TARGET)
 
-$(TARGET) :$(OBJS)
+$(shell mkdir -p $(OBJ_DIR) $(CORE_DIR))
+
+$(ELF_TARGET): $(OBJS) $(CORE_LIB)
+	$(LD) $(LDFLAGS) $(OBJS) -L$(BUILD_DIR) -lcore $(LIBS) -o $@
+
+$(CORE_LIB): $(CORE_OBJS)
+	$(AR) rcs $@ $^
+
+# Compile your C++ files
+$(OBJ_DIR)/%.o: %.cpp $(HDRS) Makefile
+	$(CXX) $(CXXFLAGS) -c $< -o $@
+
+$(CORE_DIR)/%.o: $(ARDUINO_CORE_PATH)/%.c Makefile
+	$(CC) $(CFLAGS) -c $< -o $@
+
+$(CORE_DIR)/%.o: $(ARDUINO_CORE_PATH)/%.cpp Makefile
+	$(CXX) $(CXXFLAGS) -c $< -o $@
+
+$(TARGET): $(ELF_TARGET)
+	$(OC) -O ihex -R .eeprom $< $@
+
+flash: $(TARGET)
+	$(AD) -v -p $(MCU) -c $(PROGRAMMER) -P $(PORT) -b $(BAUD) -D -U flash:w:$<:i
+
+clean:
+	$(RM) $(TARGET) $(ELF_TARGET) $(OBJS) $(CORE_OBJS) $(CORE_LIB)
+	$(RM) -r $(BUILD_DIR)
+
+.PHONY: all flash clean