use16

	jmp	short	_start
	nop

BS_OEMName	db	"XXXXXXXX"
BPB_BytsPerSec	dw	0
BPB_SecPerClus	db	0
BPB_RsvdSecCnt	dw	0
BPB_NumFATs	db	0
BPB_RootEntCnt	dw	0
BPB_TotSec16	dw	0
BPB_Media	db	0
BPB_FATSz16	dw	0
BPB_SecPerTrk	dw	18	; required
BPB_NumHeads	dw	2	; required
BPB_HiddSec	dd	0
BPB_TotSec32	dd	0
BS_DrvNum	db	0
BS_Reserved1	db	0
BS_BootSig	db	29h	; required
BS_VolID	dd	0
BS_VolLab	db	"XXXXXXXXXXX"
BS_FilSysType	db	"XXXXXXXX"

_start:
	cli
	mov	ax, 07c0h		; set data segment
	mov	ds, ax
	mov	ax, 09e0h
	mov	ss, ax
	mov	sp, 1000h
	sti

	mov	[bootdrive], dl		; save boot drive information
	mov	si, bootdrive
	call	dump8hex

	; get drive parameter
	mov	dl, [bootdrive]
	mov	ah, 0x08
	int	13h
	mov	si, buffer + 16
	mov	[si + 0], ch		; cylinder & 0xff
	mov	[si + 4], dh		; head
	mov	al, cl
	and	al, 3fh
	mov	[si + 8], al		; sector
	shr	cl, 6
	mov	[si + 1], cl		; (cylinder & 0x300) >> 2
	call	dump8hex
	call	dump8hex
	call	dump8hex

	; get drive parameter
	mov	dl, [bootdrive]
	mov	si, buffer
	mov	ah, 0x48
	int	13h
	jc	die
	mov	si, buffer + 4
	call	dump8hex
	call	dump8hex
	call	dump8hex
die:
	hlt
	jmp	die

	; dump 32bit word
dump8hex:				; SI: address
	mov	di, hexchar
	mov	bh, 0
	mov	ah, 0eh
	mov	cx, 4
	add	si, 3
dump8hex_loop:
	mov	dl, [si]
	mov	dh, dl
	and	dx, 0ff0h
	shr	dl, 4
	mov	bl, dl
	mov	al, byte [bx + di]
	int	10h
	mov	bl, dh
	mov	al, byte [bx + di]
	int	10h
	dec	si
	loop	dump8hex_loop
	mov	al, 20h
	int	10h
	add	si, 5
	ret

hexchar:
	db	"0123456789ABCDEF"

	; workarea
bootdrive:
	dd	0
buffer:	
	dw	32
	times 30 db 0
	
	; padding, boot signature
	times 510-($-$$) db 0
	dw	0aa55h