Makefile

# Custom OS Makefile
# This Makefile allows building and running the OS on Linux, Mac, or WSL 
# without needing the Windows-specific build.bat script.

# Compilers and Linkers
# If you have an i686-elf cross-compiler in your PATH, it will be used.
# Otherwise, it falls back to standard gcc (with 32-bit flags) if available.
CC = i686-elf-gcc
LD = i686-elf-ld
ASM = nasm

# Emulator
QEMU = qemu-system-x86_64

# Flags
CFLAGS = -O2 -ffreestanding -m32 -fno-pie -fno-builtin
# Note: On native Linux gcc, you might need -m32 for the cross assembler/linker if not using i686-elf
# LDFLAGS = -m elf_i386 -Ttext 0x8000 --oformat binary
LDFLAGS = -Ttext 0x8000 --oformat binary

# Source Directories
SRC_DIR = src
INC_DIR = include
BUILD_DIR = build

# Output Files
OS_IMAGE = os-image.bin
KERNEL_BIN = kernel.bin
BOOT_BIN = bootsect.bin

# Source Files
C_SRCS := $(wildcard $(SRC_DIR)/*.c)
OBJ_FILES := $(patsubst $(SRC_DIR)/%.c, $(BUILD_DIR)/%.o, $(C_SRCS))

# Assembly Source Files
ASM_SRCS := $(SRC_DIR)/interrupt.asm $(SRC_DIR)/gdt_flush.asm
ASM_OBJS := $(patsubst $(SRC_DIR)/%.asm, $(BUILD_DIR)/%.o, $(ASM_SRCS))

.PHONY: all clean run

all: $(OS_IMAGE)

$(OS_IMAGE): $(BUILD_DIR)/$(BOOT_BIN) $(BUILD_DIR)/$(KERNEL_BIN)
	cat $^ > $@

$(BUILD_DIR)/$(KERNEL_BIN): $(BUILD_DIR)/kernel_entry.o $(ASM_OBJS) $(OBJ_FILES)
	$(LD) -m elf_i386 -o $@ $(LDFLAGS) $^

$(BUILD_DIR)/$(BOOT_BIN): $(SRC_DIR)/bootsect.asm
	@mkdir -p $(BUILD_DIR)
	$(ASM) -I$(SRC_DIR)/ -f bin $< -o $@

$(BUILD_DIR)/kernel_entry.o: $(SRC_DIR)/kernel_entry.asm
	@mkdir -p $(BUILD_DIR)
	$(ASM) -f elf $< -o $@

$(BUILD_DIR)/%.o: $(SRC_DIR)/%.asm
	@mkdir -p $(BUILD_DIR)
	$(ASM) -f elf $< -o $@

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

run: $(OS_IMAGE)
	@if [ ! -f disk.img ]; then qemu-img create -f raw disk.img 10M; fi
	$(QEMU) -fda $< -hda disk.img -display gtk,zoom-to-fit=on

clean:
	rm -rf $(BUILD_DIR)
	rm -f $(OS_IMAGE)