**
**	$Id: $
**	$Revision: $
**
**	$Filename: OpenIFF.S $
**	$Author: Christian A. Weber $
**	$Release: 19.1 $
**	$Date: 92/05/11 21:11:27 $
**
**	iff.library/IFFLib_OpenIFF
**
**	COPYRIGHT (C) 1987-1992 BY CHRISTIAN A. WEBER, BRUGGERWEG 2,
**	CH-8037 ZUERICH, SWITZERLAND.  ALL RIGHTS RESERVED.  NO PART
**	OF THIS SOFTWARE MAY BE COPIED, REPRODUCED,  OR  TRANSMITTED
**	IN ANY FORM OR BY ANY MEANS,  WITHOUT THE PRIOR WRITTEN PER-
**	MISSION OF THE AUTHOR. USE AT YOUR OWN RISK.
**


		IDNT	IFFLib_OpenIFF
		SECTION	text,CODE

		INCLUDE	"IFFLib.i"

		XREF	SetError,ClearError
		XDEF	OpenIFFFunc,NewOpenIFFFunc


******* iff.library/IFFLib_NewOpenIFF ***************************************
*
*   NAME
*	IFFLib_NewOpenIFF -- allocate memory for an IFF-file and read it
*
*   SYNOPSIS
*	ifffile = IFFLib_NewOpenIFF( filename, memattr )
*	D0                           A0        D0
*
*	IFFFILE IFFLib_OpenIFF( char * )
*
*   FUNCTION
*	This function opens a file on a disk and looks whether it's an IFF
*	file or not. If it is an IFF file, memory is allocated and the file
*	is read into memory. The 'memattr' argument is taken to define the
*	memory type. Normally memattr is set to MEMF_ANY or MEMF_PUBLIC.
*	If an error occurs, NULL is returned, and you can call
*	IFFLib_IFFError() to get the error number.
*
*   INPUTS
*	filename - Pointer to a null-terminated string
*	memattr  - Memory requirements as used for Exec's AllocMem(),
*	           such as MEMF_CHIP, MEMF_PUBLIC ...
*	           (MEMF_CLEAR is not necessary)
*
*   RESULT
*	ifffile - 'FileHandle', points to the beginning of the IFF file
*	("FORM...."), Zero if unsuccessful. Call IFFLib_IFFError() to get
*	the reason of the failure.
*
*   SEE ALSO
*	IFFLib_OpenIFF(), IFFLib_CloseIFF(), IFFLib_IFFError()
*
*   BUGS
*	None known
*
*****************************************************************************

OpenIFFFunc:	movem.l	d2-d6/a2/a5-a6,-(SP)
		moveq.l	#-1,d6			; Kein MemType angegeben
		bra.s	DoCont



******* iff.library/IFFLib_OpenIFF ******************************************
*
*    NAME
*	IFFLib_OpenIFF -- allocate memory for an IFF-file and read it
*
*    SYNOPSIS
*	ifffile = IFFLib_OpenIFF( filename )
*	D0                        A0
*
*	IFFFILE IFFLib_OpenIFF( char * )
*
*    FUNCTION
*	This function does the same as the IFFLib_NewOpenIFF() routine
*	above, except that you cannot specify the type of memory which is
*	allocated for the file. Normally the type is 0 which means 'any
*	memory', but if the IFF file type is '8SVX', the file is ALWAYS
*	loaded into CHIP memory. If you wish to override these defaults,
*	use IFFLib_NewOpenIFF() instead of IFFLib_OpenIFF().
*
*   INPUTS
*	filename - Pointer to a null-terminated string
*
*   RESULT
*	ifffile - 'FileHandle', points to the beginning of the IFF file
*	("FORM...."), 0 if unsuccessful. Call IFFError() to get the
*	reason of the failure.
*
*   BUGS
*	None
*
*   SEE ALSO
*	IFFLib_NewOpenIFF(), IFFLib_CloseIFF(), IFFLib_IFFError()
*
*****************************************************************************

NewOpenIFFFunc:	movem.l	d2-d6/a2/a5-a6,-(SP)
		move.l	d0,d6			; D6 :  MemType
DoCont:		movea.l	a6,a5			; IFFBase
		lea	-12(SP),SP		; Arbeitsspeicher reservieren
		moveq.l	#0,d5			; Fehlernummer rücksetzen

	*** File öffnen

		move.l	a0,d1			; Name
		move.l	#MODE_OLDFILE,d2	; accessmode
		movea.l	ib_DOSBase(a5),a6
		JSRLIB	Open
		move.l	d0,d4			; D4 := FileHandle
		bne.s	1$
		moveq	#IFF_CANTOPENFILE,d5
		bra.s	.Error2			; --->
1$:
	*** Erste 12 Bytes lesen, testen ob 'FORM'

		move.l	d4,d1			; File
		move.l	SP,d2			; Adr
		moveq.l	#12,d3			; Len
		JSRLIB	Read			; erste 3 Longwords lesen
		cmpi.l	#'FORM',(SP)
		beq.s	2$
		moveq	#IFF_NOTIFF,d5
		bra.s	.Error1			; --->
2$:
	*** Testen ob Chip-Speicher erwünscht (bei 8SVX-Files)

		move.l	d6,d1			; Default-Requirements
		bpl.s	3$			; sind gültig --->
		moveq.l	#MEMF_PUBLIC,d1
		cmpi.l	#'8SVX',8(SP)		; 8SVX-File ?
		bne.s	3$			; nein --->
		moveq.l	#MEMF_CHIP|MEMF_PUBLIC,d1 ; sonst CHIP-Memory!
3$:
	*** Speicher für File reservieren

		moveq.l	#12,d2			; 'Remember' + FORM....
		move.l	4(SP),d3		; D3 :  FORM-Länge
		add.l	d3,d2			; D2 :  Gesamtlänge
		subq.l	#4,d3	; FUCK!!! IFF-Typ ist ja schon gelesen!
		move.l	d2,d0
		movea.l	ib_SysBase(a5),a6
		JSRLIB	AllocMem		; requirements von D1
		movea.l	d0,a2			; A2 :  IFFFile-Adresse
		tst.l	d0
		bne.s	4$			; OK --->
		moveq	#IFF_NOMEM,d5
		bra.s	.Error1			; --->
4$:
	*** File einladen

		move.l	d2,(a2)+		; Länge des reserv. Bereichs
		move.l	d4,d1			; File
		move.l	a2,d2			; Adr
		addq.l	#8,d2			; FORM.... schon gelesen!
		addq.l	#4,d2			; IFF-Typ schon gelesen
		movea.l	ib_DOSBase(a5),a6
		JSRLIB	Read			; D3 war schon Länge
		tst.l	d0
		bpl.s	5$			; OK --->
		moveq	#IFF_READERROR,d5
		bra.s	.Error1
5$:
		movem.l	(SP),d0-d2		; FORM, Länge und Type
		movem.l	d0-d2,(a2)		; IFF-Filetyp

.Error1:	move.l	d4,d1			; File
		movea.l	ib_DOSBase(a5),a6
		JSRLIB	Close

.Error2:	move.l	d5,d0			; Error ?
		beq.s	6$			; nein --->
		bsr	SetError		; Löscht auch D0
		bra.s	Ende
6$:
		bsr	ClearError
		move.l	a2,d0			; Adresse als Return-Code
Ende:
		lea	12(SP),SP		; Lokalen Speicher freigeben
		movem.l	(SP)+,d2-d6/a2/a5-a6
		rts

		END