d 	.title	datasect manipulate data sections
È 	.psect	$code	pic,usr,con,lcl,rel,shr,exe,rd,nowrt
,	.enable	debug
	;alternative way of handling files: in bulk rather than
ô	;record by record, using the pager to do the I/O
X	; to open an existing file (create if none exixts):
¼	;  CALL DSOPENON(vap, alq, filespec, pfc);
 	;	vap = ptr, datasec will store addr of its control block
„	;	alq = fixed bin(31), #blocks (512 by) if create
è	;	filespec = char(*) var
L	;	pfc = fixed bin(31), size of page fault cluster
°	; to open for read only access:
	;  STS$VALUE = DSOPENRO(vap, alq, filespec, pfc);
x	; to checkpoint, ie force a page-out of all modified page clusters:
Ü	;  CALL DSCHKPTW(vap,efn);
@	;  	vap = as above
¤	;	efn = fixed bin(31) event flag to use to test completion of I/O
	; to close:
l	;  CALL DSCLOSE(vap);
Ð	;	vap = as above; DATASECT will free the memory and set
4	;			vap null
˜	; to access:
ü	;  DCL DATA CHAR(...) BASED(DSPTR);
`		;  DCL DSPTR PTR BASED(vap);
Ä		; the FAB is located at vap+16	
(
	; the XABFHC is loacated at vap+96
Œ
	; dsopenon & dsopenro use the first longword on the stack to flag
ð
	;  which one of them was entered.  this is addressed as -4(fp).
T	; the second longword (pushed) is the pagecount, addressed as -8(fp)
¸        ;
	; r6 -> control block (=vap)
€	; r7 -> fab (vap+16)
ä	; see dsget.pli for layout of control block
H        ; t dow 6/14/82 *************************************
¬	; version 1a t dow 6/17/82  mods for dsget & dsrewind:
	;	init next_rec (vap+8->) to lo_addr(vap->)
t	;       init last_byte (vap+12->) to lo_addr + file_size_in_bytes -1
Ø	;		( = loaddr-1 if new file)
<	;
 	$jpidef
	$ssdef
h	$secdef
Ì        $rmsdef
0x144:	.long	144		;size of control block
”fabshel:
ø	$fab	fac=put,alq=0,fop=<ufo,cif,cbt>,rfm=fix,mrs=512
\fhcshel:
À	$xabfhc
$jpishel:
ˆ	.word	4
ì	.word	jpi$_frep0va
P	.long	0,0,0,0
´	.long	^X5FFFFFFF
	;
|dsopenro::
à	.word	^m<r2,r3,r4,r5,r6,r7,r8>
D	pushl	#1		;flag indicating dsopenro not dsopenon
¨	brb	dsopn
dsopenon::
p	.word	^M<r2,r3,r4,r5,r6,r7,r8>
Ô	pushl	#0		;flag indicating dsopenon not dsopenro
8dsopn:	subl2	#4,sp		;get storage for pagecount
œ	pushal	@4(ap)
 	pushal	x144
dgetvm:	calls	#2,lib$get_vm	; allocate heap for control block
È	blbs	r0,11$		;
,	brw	error
11$:	movl	@4(ap),r6	;vap
ô	moval	16(r6),r7	;r7->fab
X	movc3	#80,fabshel,(r7)
¼	movc3	#44,fhcshel,80(r7)
 	movl	12(ap),r8	;addr file name string desriptor
„	movl	4(r8),r8	;addr of length word for filespec
†        tstl    -4(fp)
ˆ        beql    on
èro:	$fab_store  fab=r7,alq=@8(ap),fna=2(r8),fns=(r8),xab=80(r7),-
é                    fac=get,shr=get
ê        brw comn
ìon:	$fab_store  fab=r7,alq=@8(ap),fna=2(r8),fns=(r8),xab=80(r7)
Lcomn:	ashl    #9,@8(ap),r1	;max rec size = 512*alq
°        movl	@8(ap),-8(fp)	; init pagecount
	movl	r1,fab$w_mrs(r7)
x	movl	#-1,12(r6)	;init file size in bytes
Ü	tstl	-4(fp)		;dsopenon or ...ro
@	beql	opnc
¤opno:	bicl2	#fab$m_cif,fab$l_fop(r7)	;turn off create-if option
 	$open	fab=(r7)
l 	blbs	r0,setalq
Ð 	brw	error
4!opnc:	$create	fab=(r7)	;rms opens
˜!	blbs	r0,11$
ü!	brw	error
`"11$:	cmpl	r0,#rms$_created
Ä"	beql	crted
(#setalq:	movl	xab$l_ebk+80(r7),@8(ap)
Œ#	movl	@8(ap),-8(fp)
ð#	decl	@8(ap)		;actual file size = eof blk - 1
T$	;  			 compute file size in bytes
¸$	ashl	#9,@8(ap),r1
%	addl2	r1,12(r6)
€%	movzwl	xab$w_ffb+80(r7),r1  ; add partial block
ä%	addl2   r1,12(r6)
H&crted:	subl2	#24,sp		;get mem for jpi call
¬&	movc3	#24,jpishel,(sp)  ;set up itemlist
'	moval	16(sp),4(sp)	;addr to hold addr of next free page
t'	movl	sp,r8
Ø'jpi:	$getjpi_s  itmlst=(r8)
<(	blbs	r0,11$
 (	brw	error
)11$:
h)	;
Ì)	tstl	-4(fp)			;check ...on or ...ro
0*	beql	mapsc
”*mapso:	$crmpsc_s  inadr=16(r8),-	;base addr supplied by getjpi
ø*		   retadr=(r6),-	;return addr, to control block
\+		   pagcnt=-8(fp),-	; note section is not writeable
À+		   chan=fab$l_stv(r7),-
$,		   pfc=@16(ap)
ˆ,	brw	   opnret
ì,mapsc:	$crmpsc_s  inadr=16(r8),-	;base addr supplied by getjpi
P-		   retadr=(r6),-	;return addr, to control block
´-		   pagcnt=-8(fp),-      
.		   flags=#sec$m_wrt,-   ;section is writeable
|.		   chan=fab$l_stv(r7),-
à.		   pfc=@16(ap)
D/opnret:	blbs	r0,11$
¨/	brw	error
011$:	movl	(r6),8(r6)		;init next_rec
p0	addl2	(r6),12(r6)		;compute last_byte
Ô0	ret
81	;
œ1dschkptw::
 2	.word	0
d2	$clref_s  efn=@8(ap)
È2	blbc	r0,error
,3	movl	@4(ap),r1
3	$updsec_s inadr=(r1),efn=@8(ap)
ô3tstm:	cmpl	r0,#ss$_notmodified
X4	bneq	1$
¼4	ret	;ie, no modified pages since last system pageout
 51$:	cmpl	r0,#ss$_normal ;if we were being defensive
„5	bneq	error
è5	$waitfr_s efn=@8(ap)  ; wait for completion of pageouts
L6	ret
°6	;
7dsclose::
x7	.word	^m<r2,r3,r4,r5,r6>
Ü7        movl	@4(ap),r6
@8	$deltva_s  inadr=(r6) ;release the virtual addr space
¤8	blbc	r0,error
9	$dassgn_s  chan=16+fab$l_stv(r6)
l9        blbc	r0,error
Ð9	pushal	@4(ap)
4:	pushal  x144
˜:	calls	#2,lib$free_vm	;free the control block
ü:	blbc	r0,error
`;	clrl	@4(ap)		;null out the ptr
Ä;	ret
(<error:	
Œ<	movl	r0,r6
ð<	clrl	-(sp)
T=	pushl	r0
¸=	pushl	#2
>	movl	sp,r1
€>	$putmsg_s msgvec=(r1)
ä>	movl	r6,r0		;restore calling error code
?        clrl    @4(ap)
H?	ret
¬?	.end