Added builder

bootloader/bios.mk

@@ -0,0 +1,30 @@
+# 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="$(BIOS_BUILD)/bios.bin" bs=512 skip=1 of="$@"