SRC_DIR=src
INCLUDE_DIR=include
BUILD_DIR=build

K_BIN_NAME=kernel.bin
ISO_NAME=os_image.iso

CC=cc
LD=ld

CFLAGS+=-std=c2x -ffreestanding -fno-stack-protector -g -Wall -Wextra -pedantic -lgcc -isystem $(INCLUDE_DIR)
CFLAGS+=-DPAGE_SIZE=4096

LDFLAGS+=-nmagic

C_SRC=$(shell find $(SRC_DIR) -type f -name "*.c")
C_OBJ=$(patsubst %.c,$(BUILD_DIR)/%.o,$(C_SRC))

H_SRC=$(shell find $(SRC_DIR) -type f -name "*.h")
H_INCLUDE=$(shell find $(INCLUDE_DIR) -type f -name "*.h")

A_SRC=$(shell find $(SRC_DIR) -type f -name "*.S")
A_OBJ=$(patsubst %.S,$(BUILD_DIR)/%.S.o,$(A_SRC))

.PHONY: all clean

all: $(BUILD_DIR)/$(ISO_NAME)

clean:
	rm -rf $(BUILD_DIR)/*

$(A_OBJ): $(BUILD_DIR)/%.S.o : %.S
	@mkdir -p $(@D)
	nasm $< -f elf64 -o $@

$(C_OBJ): $(BUILD_DIR)/%.o : %.c
	@mkdir -p $(@D)
	$(CC) -c $(CFLAGS) -o $@ $<

$(BUILD_DIR)/$(K_BIN_NAME): arch/amd64/linker.ld $(A_OBJ) $(C_OBJ) $(H_SRC) $(H_INCLUDE)
	@mkdir -p $(@D)
	$(LD) $(LDFLAGS) -T arch/amd64/linker.ld -o $(BUILD_DIR)/$(K_BIN_NAME) $(A_OBJ) $(C_OBJ)

$(BUILD_DIR)/$(ISO_NAME): $(BUILD_DIR)/$(K_BIN_NAME) grub.cfg
	@mkdir -p $(@D)
	@mkdir -p $(BUILD_DIR)/iso/boot/grub
	cp grub.cfg $(BUILD_DIR)/iso/boot/grub
	cp $(BUILD_DIR)/$(K_BIN_NAME) $(BUILD_DIR)/iso/boot
	grub-mkrescue -o $(BUILD_DIR)/$(ISO_NAME) $(BUILD_DIR)/iso

run: all
	qemu-system-x86_64 \
		-cdrom $(BUILD_DIR)/$(ISO_NAME) \
		-serial stdio \
		-m 4G \
		-name corn