.code16
		.globl	start

		.org	0x0, 0x0
	
start:		movl	$0x7c0, %eax
		movw	%ax, %ds
		xorl	%ebx, %ebx
		movw	%bx, %ss
		movl	$0x7c00, %esp	# set up the stack
		movb	%dl, %bl
		movl	$(boot_message+0xf), %edi
		shrb	$0x4, %bl
		movb	hexchars(%ebx), %al
		movb	%al, (%edi)
		incl	%edi
		movb	%dl, %bl
		andb	$0xf, %bl
		movb	hexchars(%ebx), %al
		movb	%al, (%edi)
		movl	$message, %esi
		call	putstr
		movl	$crlf, %esi
		call	putstr
		movl	$boot_message, %esi
		call	putstr
end:		jmp	end

		nop
		nop
	
putstr:		lodsb
		testb	%al,%al		# stop at null
		jnz	putc
		ret			# return when null is hit
putc:		movl	$0x7,%ebx
		movb	$0xe,%ah	# BIOS: put_char
		int	$0x10		# call BIOS, print char in %al
		jmp	putstr		# keep looping
		
message:	.ascii	"Testing, 1... 2... 3..."
	
crlf:		.byte	13, 10, 0
	
hexchars:	.ascii	"0123456789abcdef"
	
boot_message:	.asciz "boot device: 0xXX"