# environment

AARCH64_TOOLCHAIN ?= aarch64-linux-gnu


# Shortcuts

CC=clang --target=aarch64-none-elf -mcpu=cortex-a57
LD=ld.lld
OBJCOPY=$(AARCH64_TOOLCHAIN)-objcopy --target elf64-littleaarch64

CFLAGS += -O0
CFLAGS += -g
#CFLAGS += -nostdlib
#CFLAGS += -march=armv8-a
#CFLAGS += -std=c99
#CFLAGS += -pedantic
#CFLAGS += -Wall
#CFLAGS += -Wmissing-prototypes
#CFLAGS += -Wstrict-prototypes
#CFLAGS += -Wold-style-definition

BUILD_DIR=build


# Files

KERNEL_MEMMAP = aarch64/memmap

KERNEL_SOURCES = \
  aarch64/boot.s \
  sys/main.c \
  sys/uart.c \

KERNEL_LIST := $(wildcard $(KERNEL_SOURCES))
KERNEL_OBJS := $(addsuffix .o, $(addprefix $(BUILD_DIR)/, ${KERNEL_LIST}))

all: kernel


# compilation 

kernel: $(BUILD_DIR)/kernel.elf # $(BUILD_DIR)/kernel.sym

$(BUILD_DIR)/kernel.elf: $(KERNEL_OBJS)
	$(info linking target: $@)
	$(LD) -T$(KERNEL_MEMMAP) -nostdlib $^ -o $@
	$(info done: $@)

$(BUILD_DIR)/kernel.bin: $(BUILD_DIR)/kernel.elf
	$(OBJCOPY) -O binary $< $@

$(BUILD_DIR)/kernel.sym: $(BUILD_DIR)/kernel.elf
	$(OBJCOPY) --only-keep-debug $< $@
	$(OBJCOPY) --strip-debug $@

$(BUILD_DIR)/%.o: %
	$(info compiling file: $<)
	@mkdir -p $(dir ./$(BUILD_DIR)/$<)
	$(CC) $(CFLAGS) -c $< -o $@


.PHONY: clean run

# helpers
QEMU_CMD = \
  qemu-system-aarch64 \
    -M virt \
    -cpu cortex-a57 \
    -nographic \
    -smp 4 \
    -m 4096 \
    -kernel build/kernel.elf \
    -serial stdio \
    -monitor none \


clean:
	rm -Rf ./$(BUILD_DIR)/*

run: kernel
	$(QEMU_CMD)


debug: kernel
	$(QEMU_CMD) -S -gdb tcp::1234 & \
  gdb-multiarch -q \
  -ex 'file build/kernel.elf' \
  -ex 'target remote localhost:1234'
	kill %1