include config.mk

CC ?= gcc
AVR_CC ?= avr-gcc
GDB ?= avr-gdb
OBJCOPY ?= avr-objcopy
AVRDUDE ?= avrdude
QEMU ?= qemu-system-avr

# options for native (i.e. unit test)
UNITY_SRC ?= unity/src
UNITY_O = $(UNITY_SRC)/unity.o
CFLAGS += -Wall -Wextra -I$(UNITY_SRC)
LDFLAGS += -lm

# options for cross-compile
MCU ?= atmega32u4
SIM_MCU ?= atmega2560

# Compiler flags for cross-compile
AVR_COMMON_CFLAGS += -Wall -Wextra -DF_CPU=16000000UL
AVR_CFLAGS += $(AVR_COMMON_CFLAGS) -mmcu=$(MCU) -O3
SIM_CFLAGS += $(AVR_COMMON_CFLAGS) -mmcu=$(SIM_MCU) -g3 -gdwarf-2 -DWDT_DISABLE

# Linker flags for cross-compile
AVR_COMMON_LDFLAGS += -Wl,-u,vfprintf -lprintf_flt
AVR_LDFLAGS += $(AVR_COMMON_LDFLAGS) -mmcu=$(MCU)
SIM_LDFLAGS += $(AVR_COMMON_LDFLAGS) -mmcu=$(SIM_MCU)

$(shell mkdir -p build/{real,sim,native})

all: build/altimeter_sim.elf build/altimeter.hex test

# Run the sim build software in qemu, halted ready for `make gdb` to attach and
# continue. Note that sim build mocks out some hardware components
emu: build/altimeter_sim.elf
	$(QEMU) -s -S -nographic -machine mega2560 -bios $<

# Attach GDB session to qemu instance started with `make emu`
gdb:
	$(GDB) -ex "target remote :1234"
# Flash AVR software to microcontroller with AVRdude
flash: build/altimeter.hex
	$(AVRDUDE) -F -V -c avr109 -p $(MCU) -P $(PORT) -b 115200 -U flash:w:$<

clean:
	rm -rf build/ $(UNITY_O)

test: \
	$(UNITY_O) \
	build/native/test_util.o \
	build/native/util.o
	$(CC) $(LDFLAGS) -o $@ $^
	./$@

# ELF for real hardware. No mock/sim hardware included (except barometer,
# haven't written that code yet)
build/altimeter.elf: \
	build/real/barometer_sim.o \
	build/real/display_sim.o \
	build/real/altimeter.o \
	build/real/util.o
	$(AVR_CC) $(AVR_LDFLAGS) -o $@ $^

# ELF for simulator/emu. Note that whever I/O is required, the *_sim.{o,c}
# versions of each component will provide a mocked interface. This allows for
# operation in QEMU (see `emu` recipe) without requring SPI, I²C and
# peripherals to be emulated. Useful for UI testing and development etc.
build/altimeter_sim.elf: \
	build/sim/barometer_sim.o \
	build/sim/display_sim.o \
	build/sim/altimeter.o \
	build/sim/util.o
	$(AVR_CC) $(SIM_LDFLAGS) -o $@ $^

build/sim/%.o: %.c
	$(AVR_CC) $(SIM_CFLAGS) -c -o $@ $^

build/real/%.o: %.c
	$(AVR_CC) $(AVR_CFLAGS) -c -o $@ $^

build/native/%.o: %.c
	$(CC) $(CFLAGS) -c -o $@ $^

build/%.hex: build/%.elf
	$(OBJCOPY) -O ihex -R .eeprom $< $@

build/%.elf:
	$(AVR_CC) $(AVR_CFLAGS) -o $@ $^

.PHONY: all emu gdb flash clean test