BUILD ?= build
PREFIX ?= arm-none-eabi

all: $(BUILD)/tbm

LDSCRIPT = support/stm32f0-discovery.ld

CFLAGS += -Iinclude
CFLAGS += -Wall -Wundef -Wextra -Wshadow -Wimplicit-function-declaration
CFLAGS += -Wredundant-decls -Wmissing-prototypes -Wstrict-prototypes
CFLAGS += -fno-common --function-sections -fdata-sections
LDFLAGS += -static -nostartfiles
LDFLAGS += -Wl,--gc-sections
LIBS += -Wl,--start-group -lc -lgcc -lnosys -Wl,--end-group

# Set up libopencm3.
OPENCM3_DIR ?= libopencm3
OPENCM3_LIBNAME = opencm3_stm32f0
CFLAGS += -I$(OPENCM3_DIR)/include
CFLAGS += -DSTM32F0 -msoft-float -mthumb -mcpu=cortex-m0
LDFLAGS += -L$(OPENCM3_DIR)/lib
LIBS += -l$(OPENCM3_LIBNAME)

STLINK_PORT ?= :4242

obj-y += source/main.o
obj-y += source/shell.o
obj-y += source/spi_flash.o
obj-y += source/usart.o

obj = $(addprefix $(BUILD)/, $(obj-y))

# Include the dependencies.
-include $(obj:.o=.d)

# Set up the toolchain.
CC := $(PREFIX)-gcc
LD := $(PREFIX)-gcc
GDB := $(PREFIX)-gdb
MAKE := make

.SECONDARY:

clean:
	@echo "CLEAN"
	@rm -rf $(BUILD)

$(OPENCM3_DIR)/lib/lib$(OPENCM3_LIBNAME).a:
	@if [ ! -e libopencm3/.git ]; then \
		git submodule init; \
		git submodule update; \
	fi
	@$(MAKE) -C $(OPENCM3_DIR)

# Rule to compile C source code.
$(BUILD)/%.o: %.c
	@echo "CC $<"
	@mkdir -p $(dir $@)
	@$(CC) -c $< -o $@ $(CFLAGS) -MT $@ -MMD -MP -MF $(@:.o=.d)

$(BUILD)/tbm: $(obj) $(LDSCRIPT) $(OPENCM3_DIR)/lib/lib$(OPENCM3_LIBNAME).a
	@echo "LD $@"
	@mkdir -p $(dir $@)
	@$(LD) -o $@ $(CFLAGS) $(LDFLAGS) -T $(LDSCRIPT) $(obj) $(LIBS)

run: $(BUILD)/tbm
	@echo "GDB $<"
	@$(GDB) --batch \
		-ex 'target extended-remote $(STLINK_PORT)' \
		-x flash.scr \
		$<

.PHONY: clean run