# -------------------------------------------------------
# Real Mode OS Makefile
# Tools: NASM, OpenWatcom (wcc/wlink), QEMU
# -------------------------------------------------------

# Tools
NASM        := nasm
WCC         := wcc
WLINK       := wlink
QEMU        := qemu-system-i386
DD          := dd

# Flags
NASM_BIN    := -f bin
NASM_OBJ    := -f obj
WCC_FLAGS   := -ms -0 -wx -s -ecc   # small model, 8086, warnings, no stack check, cdecl
QEMU_FLAGS   = -fda $(IMG) -monitor stdio

# Output names
BOOT_SRC    := boot.asm
ENTRY_SRC   := entry.asm
KMAIN_SRC   := kmain.c
LINK_FILE   := kernel.lnk

BOOT_BIN    := bootloader.bin
ENTRY_OBJ   := entry.obj
KMAIN_OBJ   := kmain.obj
KERNEL_BIN  := kernel.bin
IMG         := floppy.img

BIOS_SRC := bios.asm
BIOS_OBJ := bios.obj



# -------------------------------------------------------
# Default target
# -------------------------------------------------------
.PHONY: all clean run debug

all: $(IMG)

# -------------------------------------------------------
# Bootloader — flat binary
# -------------------------------------------------------
$(BOOT_BIN): $(BOOT_SRC)
	$(NASM) $(NASM_BIN) $< -o $@

# -------------------------------------------------------
# Kernel entry point — OMF object
# -------------------------------------------------------
$(ENTRY_OBJ): $(ENTRY_SRC)
	$(NASM) $(NASM_OBJ) $< -o $@

# -------------------------------------------------------
# C kernel — OMF object via OpenWatcom
# -------------------------------------------------------
$(KMAIN_OBJ): $(KMAIN_SRC)
	$(WCC) $< $(WCC_FLAGS) -fo=$@

$(BIOS_OBJ): $(BIOS_SRC)
	$(NASM) $(NASM_OBJ) $< -o $@

$(KERNEL_BIN): $(ENTRY_OBJ) $(BIOS_OBJ) $(KMAIN_OBJ) $(LINK_FILE)
	$(WLINK) @$(LINK_FILE)

# -------------------------------------------------------
# Floppy image
# -------------------------------------------------------
$(IMG): $(BOOT_BIN) $(KERNEL_BIN)
	$(DD) if=/dev/zero    of=$@          bs=512 count=2880
	$(DD) if=$(BOOT_BIN)  of=$@ conv=notrunc
	$(DD) if=$(KERNEL_BIN) of=$@ seek=1 conv=notrunc bs=512

# -------------------------------------------------------
# Run in QEMU
# -------------------------------------------------------
run: $(IMG)
	$(QEMU) $(QEMU_FLAGS)

# -------------------------------------------------------
# Debug — QEMU with GDB stub and interrupt logging
# -------------------------------------------------------
debug: $(IMG)
	$(QEMU) $(QEMU_FLAGS) \
		-s -S \
		-d int \
		-D qemu.log

# -------------------------------------------------------
# Clean
# -------------------------------------------------------
clean:
	rm -f $(BOOT_BIN) $(ENTRY_OBJ) $(KMAIN_OBJ) $(KERNEL_BIN) $(IMG) $(BIOS_OBJ)\
	      kernel.map qemu.log