# Expects variables:
# STAGE3: path to linked stage 3 binary
# STAGE2_SECTOR: the index of the first sector
# of the stage 2 binary on the disk it will be written to.

BIOS_SRC = ./bios

# Wrap bootloader in three-stage BIOS loader
$(BIOS_BUILD)/bios.bin: $(wildcard $(BIOS_SRC)/*.asm) $(BUILD)/bios.elf
	@mkdir -p "$(BIOS_BUILD)"
	nasm \
		-f bin \
		-D STAGE3="$(BUILD)/bios.elf" \
		-D STAGE2_SECTOR=$(STAGE2_SECTOR) \
		-o "$@" \
		-l "$@.lst" \
		-i "$(BIOS_SRC)" \
		"$(BIOS_SRC)/main.asm"

# Extract MBR (first 440 bytes)
$(BIOS_BUILD)/bios.mbr.bin: $(BIOS_BUILD)/bios.bin
	@mkdir -p "$(BIOS_BUILD)"
	@echo ""
	dd if="$(BIOS_BUILD)/bios.bin" bs=440 count=1 of="$@"

# Extract stage 2 (rest of file)
$(BIOS_BUILD)/bios.stage2.bin: $(BIOS_BUILD)/bios.bin
	@mkdir -p "$(BIOS_BUILD)"
	@echo ""
	dd if="$(BIOS_BUILD)/bios.bin" bs=512 skip=1 of="$@"