title	Module from library C_2 : UBDOS
	name	('UBDOS')

; Do file OS call with user setting

; Copyright (C)	Werner Cirsovius
;		Hohe Weide 44
;		D-20253 Hamburg
;		Tel.: +49 040 4223247

;		Version 1.0 July 1994

; ENTRY	Reg C holds OS function number
;	Reg pair DE points to file block

; EXIT	Accu and reg HL hold resulting code

	maclib	c.lib

	entry	u$bdos

	extrn	$bdos

u$bdos:
	ld	hl,_U
	add	hl,de
	ld	a,(hl)		; Get user
	or	a
	jp	z,$bdos		; .. none, so go do OS call
	push	bc
	push	de
	push	af
	ld	c,.usrcod
	ld	e,_get
	call	$bdos		; Get old user
	ex	(sp),hl
	ld	e,h
	dec	e		; .. fix user
	ld	c,.usrcod
	call	$bdos		; .. set new area
	pop	hl
	pop	de
	pop	bc
	push	hl
	call	$bdos		; Do OS call
	ex	(sp),hl
	push	bc
	push	de
	ld	e,l		; Get old user
	ld	c,.usrcod
	call	$bdos		; .. set it
	pop	de
	pop	bc
	pop	hl
	ld	a,l
	ret

	end