Makefile

TARGET = dma-usart


# Configure micro-controller
MCU_FAMILY	= STM32F103xB
LDSCRIPT 	= stm32f1.ld
CPU			= cortex-m3
INSTR_SET	= thumb
FLOAT_ABI	= soft

# compiler option
OPT			:= -Os
CSTD		?= gnu11
CXXSTD		:= gnu++17

# Project specific configuration
BUILD_DIR 	:= build
BUILD_TYPE	?= Debug
SRC_DIR 	:= src
INC_DIRS	:= include


PREFIX		?= arm-none-eabi
CC			:= $(PREFIX)-gcc
CXX			:= $(PREFIX)-g++
LD			:= $(PREFIX)-gcc
AR			:= $(PREFIX)-ar
AS			:= $(PREFIX)-as
SIZE		:= $(PREFIX)-size
OBJCOPY		:= $(PREFIX)-objcopy
OBJDUMP		:= $(PREFIX)-objdump
GDB			:= $(PREFIX)-gdb

# collect source files and generate object files
SRCS 		:= $(shell find $(SRC_DIR) -name '*.cpp' -or -name '*.c')	
OBJS 		:= $(addsuffix .o,$(basename $(SRCS)))			# replace .c with .o
OBJS 		:= $(addprefix $(BUILD_DIR)/,$(OBJS))			# replace .c with .o
ASMS 		:= $(addsuffix .s,$(basename $(OBJS)))

# Define stm32 family macro
DEFS		+=-D$(MCU_FAMILY)

# header library include flsgs
INC_FLAGS 	=$(addprefix -I,$(INC_DIRS))


# Target-specific flags
CPU_FLAGS	?=-mfloat-abi=$(FLOAT_ABI) -m$(INSTR_SET) -mcpu=$(CPU)
CPPFLAGS	?=$(DEFS) $(INC_FLAGS) -MMD

# optiomization level according to build type
ifeq ($(BUILD_TYPE), Debug)
CFLAGS 		+= -g -gdwarf-2
CXXFLAGS 	+= -g -gdwarf-2
LDFLAGS 	+= -g -gdwarf-2
else
CFLAGS		+= $(OPT)
CXXFLAGS	+= $(OPT)
ASFLAGS		+= $(OPT)
endif

# Do not link stdlib with executable
CFLAGS		+= -nostdlib -fno-tree-loop-distribute-patterns -fdata-sections -ffunction-sections
CXXFLAGS	+= -nostdlib -fno-tree-loop-distribute-patterns -fdata-sections -ffunction-sections -fno-exceptions -fno-rtti
LDFLAGS		+= -nostdlib 


# Warning options for C and CXX compiler
CFLAGS		+= -Wall -Wextra -Wundef -Wshadow -Wredundant-decls -Wmissing-prototypes -Wstrict-prototypes
CXXFLAGS	+= -Wall -Wextra -Wundef -Wshadow -Wredundant-decls -Weffc++ -Werror

# Linker options
LDFLAGS		+= -T $(LDSCRIPT)
LDFLAGS		+= -Wl,-Map=$(basename $@).map,--gc-sections,-cref,--print-memory-usage

all		: size bin
size	: $(BUILD_DIR)/$(TARGET).size
elf		: $(BUILD_DIR)/$(TARGET).elf
bin		: $(BUILD_DIR)/$(TARGET).bin
hex		: $(BUILD_DIR)/$(TARGET).hex
srec	: $(BUILD_DIR)/$(TARGET).srec
list	: $(BUILD_DIR)/$(TARGET).list
asm		: $(ASMS)

# binary file to flash on target
%.bin: %.elf
	@echo "COPY " $< " => " $@
	@$(OBJCOPY) -Obinary $(*).elf $(*).bin

# executable object files for debugging
%.hex: %.elf
	$(OBJCOPY) -Oihex $(*).elf $(*).hex

%.srec: %.elf
	$(OBJCOPY) -Osrec $(*).elf $(*).srec

%.list: %.elf
	$(OBJDUMP) -S $(*).elf > $(*).list

%.size: %.elf
	@echo "Section wise usage: "
	@$(SIZE) $<

# Build assembly files
$(BUILD_DIR)/%.s:%.c
	@mkdir -p $(dir $@)
	@echo "AS" $< " ==> " $@
	@$(CC) $(CPU_FLAGS) $(CPPFLAGS) $(CFLAGS) -o $@ -S $<

$(BUILD_DIR)/%.s:%.cpp
	@mkdir -p $(dir $@)
	@echo "AS" $< " ==> " $@
	@$(CXX) $(CPU_FLAGS) $(CPPFLAGS) $(CXXFLAGS) -o $@ -S $<

# Object files
$(BUILD_DIR)/%.o:%.c
	@mkdir -p $(dir $@)
	@echo "CC" $< " ==> " $@
	@$(CC) $(CPU_FLAGS) $(CPPFLAGS) $(CFLAGS) -o $@ -c $<

$(BUILD_DIR)/%.o:%.cpp
	@mkdir -p $(dir $@)
	@echo "CXX" $< " ==> " $@
	@$(CXX) $(CPU_FLAGS) $(CPPFLAGS) $(CXXFLAGS) -o $@ -c $<

# final executable object file
$(BUILD_DIR)/$(TARGET).elf: $(OBJS) $(LDSCRIPT)
	@echo "Linking sources into "$@
	@$(CC) $(CPU_FLAGS) $(LDFLAGS) -o $@ $(OBJS)

# upload binary to stm32
flash: bin
	st-flash write $(BUILD_DIR)/$(TARGET).bin 0x8000000

# remove generated files 
clean:
	rm -rf build

# include generated rules
-include $(OBJS:%.o=%.d)