# Build script for BIOS (legacy) boot.
#
# This compiles our bootloader as a static library,
# and wraps it in a multistage loader.


BUILD = ./build
BIOS_BUILD = $(BUILD)/bios

STAGE2_SECTOR=34

.PHONY: all
all: $(BIOS_BUILD)/bios.mbr.bin $(BIOS_BUILD)/bios.stage2.bin

.PHONY: clean
clean:
	rm -drf $(BUILD)

include bios.mk

# Compile bootloader as library
LIB_SRC = ./bootloader/Cargo.toml ./bootloader/Cargo.lock $(shell find ./bootloader/src -type f)
$(BUILD)/bios.lib: $(LIB_SRC)
	@mkdir -p $(BUILD)
	env RUSTFLAGS="-C soft-float" \
	cargo rustc \
		--manifest-path="./bootloader/Cargo.toml" \
		-Z build-std=core,alloc \
		-Z build-std-features=compiler-builtins-mem \
		--target "./bootloader/targets/x86-unknown-none.json" \
		--lib \
		--release \
		-- \
		--emit link="$(CURDIR)/$@"

# Link bootloader
BIOS_LD = ./bootloader/linkers/x86-unknown-none.ld
$(BUILD)/bios.elf: $(BUILD)/bios.lib $(BIOS_LD)
	ld \
		-m elf_i386 \
		--gc-sections \
		-z max-page-size=0x1000 \
		-T "$(BIOS_LD)" \
		-o "$@" \
		"$<"

	objcopy --only-keep-debug "$@" "$@.sym"
	objcopy --strip-debug "$@"