; reset segments
rstseg	mov ax, cs
	mov ds, ax
	mov es, ax
	ret

	; copy to far memory
	; IN	es:bx	far memory ptr (preserved)
	;	ds:dx	local ptr (preserved)
	;	cx	number of bytes to transfer
	; OUT	cx	set to zero
	;	si & di	trashed
stofar	mov si, dx
	mov di, bx
	rep movsb
	ret

	; copy from far memory
	; IN	es:bx	far memory ptr (preserved)
	;	ds:dx	local ptr (preserved)
	;	cx	number of bytes to copy
	; OUT	cx	set to zero
	;	si & di	trashed
lodfar	call xchgdes
	mov si, bx
	mov di, dx
	rep movsb

	; exchange es and ds
xchgdes	push ds
	push es
	pop ds
	pop es
	ret

	; normalize ptr in ds:dx
norm	mov ax, ds
	mov cl, 4
	push dx
	ror dx, cl
	and dh, 0xF
	add ax, dx
	mov ds, ax
	pop dx
	and dx, 0xF
	ret