SRC_DIR   := src
BUILD_DIR := build
OBJ_DIR   := $(BUILD_DIR)
BIN_DIR   := $(BUILD_DIR)/bin

IMG := $(BIN_DIR)/kernel8.img
ELF := $(BIN_DIR)/kernel8.elf

SRC     := $(wildcard $(SRC_DIR)/*.c)
OBJ     := $(SRC:$(SRC_DIR)/%.c=$(OBJ_DIR)/%.o)
ASM_SRC := $(wildcard $(SRC_DIR)/*.s)
ASM_OBJ := $(ASM_SRC:$(SRC_DIR)/%.s=$(OBJ_DIR)/%.o)
LINK    := $(SRC_DIR)/link.ld

CPPFLAGS := -I$(SRC_DIR) -MMD -MP
CFLAGS   := -Wall -Wextra -O2 -ffreestanding -nostdinc -nostdlib -nostartfiles
LDFLAGS  := -nostdlib

TOOLCHAIN := $(HOME)/bin/arm-gnu-toolchain-14.2.rel1-x86_64-aarch64-none-elf/bin
AS        := $(TOOLCHAIN)/aarch64-none-elf-as
CC        := $(TOOLCHAIN)/aarch64-none-elf-gcc
LD        := $(TOOLCHAIN)/aarch64-none-elf-ld
OBJCOPY   := $(TOOLCHAIN)/aarch64-none-elf-objcopy

.PHONY: all clean

all: $(IMG)

$(IMG): $(ELF) | $(BIN_DIR)
	@echo Building $@
	$(OBJCOPY) -O binary $(ELF) $@

$(ELF): $(OBJ) $(ASM_OBJ) | $(BIN_DIR)
	@echo Building $@
	$(LD) $(LDFLAGS) $^ -T $(LINK) -o $@

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.c | $(BUILD_DIR)
	@echo Building $< "->" $@
	$(CC) $(CFLAGS) -c $< -o $@

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.s | $(BUILD_DIR)
	@echo Building $< "->" $@
	$(AS) $< -o $@

clean:
	rm -rf $(BUILD_DIR)

$(BUILD_DIR):
	mkdir -p $(BUILD_DIR)
	
$(BIN_DIR):
	mkdir -p $(BIN_DIR)