CC := gcc
CFLAGS := -std=c99 -m32 -ffreestanding -O0 -g -Wall -Werror
LD := ld
NASMFLAGS := -f elf32
NASM := nasm
OBJCOPY := objcopy
MAGIC = $(shell printf '%x' `date +%s`)

all: image.bin kernel.sym

image.bin: boot.bin kernel.bin magic.bin
	cat boot.bin kernel.bin > image.tmp
	# truncate to correct number of sectors, we have
	# 512 (boot, stage 1) + N * 512 (N currenty is 3, stage 2) = 2048 for boot.bin
	# + M * 512 (M is currently 7) = 3144 for kernel.bin
	# + 1 * 512 = 512 for magic.bin
	# (M + N + 1 is the number of sectors to be read in stage 2, as stage 1
	# loads only the first sector, so adapt NOF_LOAD_SECTORS to 16)
	truncate -s 8192 image.tmp
	cat image.tmp magic.bin > image.bin
	
boot.bin: boot.asm gdt.asm stage1_functions.asm stage2_functions.asm switch_mode.asm
	$(NASM) boot.asm -DMAGIC='"$(MAGIC)"' -f bin -o boot.bin

kernel.bin: kernel.elf
	$(OBJCOPY) -O binary kernel.elf kernel.bin

kernel.sym: kernel.elf
	$(OBJCOPY) --only-keep-debug kernel.elf kernel.sym

kernel.elf: kernel.o console.o vga.o serial.o port.o port_asm.o interrupts.o interrupts_asm.o string.o stdlib.o
	$(LD) -o kernel.elf -N -n -Ttext 0x8400 --oformat elf32-i386 \
		kernel.o console.o vga.o serial.o port.o port_asm.o \
		interrupts.o interrupts_asm.o string.o stdlib.o

magic.bin: magic.asm
	$(NASM) magic.asm -DMAGIC='"$(MAGIC)"' -f bin -o magic.bin
	
kernel.o: kernel.c
	$(CC) $(CFLAGS) -c -o kernel.o kernel.c

port.o: port.c port.h
	$(CC) $(CFLAGS) -c -o port.o port.c

port_asm.o: port.asm
	$(NASM) port.asm $(NASMFLAGS) -o port_asm.o

console.o: console.c console.h vga.h serial.h
	$(CC) $(CFLAGS) -c -o console.o console.c

vga.o: vga.c vga.h
	$(CC) $(CFLAGS) -c -o vga.o vga.c

serial.o: serial.c serial.h
	$(CC) $(CFLAGS) -c -o serial.o serial.c

interrupts.o: interrupts.c interrupts.h
	$(CC) $(CFLAGS) -c -o interrupts.o interrupts.c

interrupts_asm.o: interrupts.asm
	$(NASM) interrupts.asm $(NASMFLAGS) -o interrupts_asm.o

string.o: string.c string.h
	$(CC) $(CFLAGS) -c -o string.o string.c

stdlib.o: stdlib.c stdlib.h
	$(CC) $(CFLAGS) -c -o stdlib.o stdlib.c

clean:
	-rm -f boot.bin kernel.bin kernel.sym kernel.elf image.bin magic.bin *.o boot.map image.tmp

run-qemu: image.bin
	qemu-system-i386 -d guest_errors -m 32 -drive "file=image.bin,if=ide,format=raw" \
		-serial file:serial.log

run-qemu-debug: image.bin
	qemu-system-i386 -S -s -d guest_errors -m 32 -drive "file=image.bin,if=ide,format=raw" \
		-serial file:serial.log

run-bochs:
	bochs -q -f bochs.config 'boot:floppy' 'floppya: 1_44=image.bin, status=inserted'