.text	
		.globl	_start
		.code16
_start:		cld
		xorw	%ax, %ax
		movw	%ax, %ds
		movw	%ax, %es
		movw	%ax, %ss
		movw	$_start, %sp

		xorw	%dx, %dx
		movw	$0xe3, %ax
		int	$0x14

		movw	$0x2401, %ax
		int	$0x15

		movw	$msg, %si
		callw	puts

		lgdt	gdt_desc
		movl	%cr0, %eax
		orl	$0x1, %eax
		movl	%eax, %cr0
		pushl	$0x8
		pushl	$_start32
		lretl

puts:		lodsb
		testb	%al, %al
		jnz	puts.1
		retw
puts.1:		movb	$0x1, %ah
		xorw	%dx, %dx
		int	$0x14
		jmp	puts

		.code32
_start32:	cli
		movl	$0x10, %eax
		movl	%eax, %ds
		movl	%eax, %es
		movl	%eax, %ss

		movl	$__bss_start, %esi
		movl	$_end, %ecx
		subl	$__bss_start, %ecx
		shrl	$2, %ecx
		xorl	%eax, %eax
		rep
		stosl

		call	main
_start32.1:	jmp	_start32.1

		.data
gdt:		.word	0x0, 0x0, 0x0, 0x0
		.word	0xffff, 0x0, 0x9a00, 0xcf	# code
		.word	0xffff, 0x0, 0x9200, 0xcf	# data
gdt_desc:	.word	. - gdt - 1
		.long	gdt

msg:		.asciz	"hello from real mode...\r\n"

		.comm	pdpt, 32, 32
		.comm	ptd, 4 * 4096, 4096
		.comm	ptp, 4096, 4096