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Trailing-Edge - PDP-10 Archives - BB-H138F-BM_1988 - 7-sources/rmsasc.b36
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%TITLE 'A S C I I   -- ASCII record routines'
!<BLF/REQUIRE 'RMSBLF.REQ'>
MODULE ascii (IDENT = '2.0'
		) =
BEGIN
!
!	COPYRIGHT (C) DIGITAL EQUIPMENT CORPORATION 1984, 1986.
!	ALL RIGHTS RESERVED.
!
!	THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY  BE  USED  AND
!	COPIED ONLY IN ACCORDANCE WITH THE TERMS OF SUCH LICENSE AND WITH
!	THE INCLUSION OF THE ABOVE COPYRIGHT NOTICE.   THIS  SOFTWARE  OR
!	ANY  OTHER  COPIES  THEREOF MAY NOT BE PROVIDED OR OTHERWISE MADE
!	AVAILABLE TO ANY OTHER PERSON.  NO TITLE TO AND OWNERSHIP OF  THE
!	SOFTWARE IS HEREBY TRANSFERRED.
!
!	THE INFORMATION IN THIS SOFTWARE IS  SUBJECT  TO  CHANGE  WITHOUT
!	NOTICE  AND  SHOULD  NOT  BE CONSTRUED AS A COMMITMENT BY DIGITAL
!	EQUIPMENT CORPORATION.
!
!	DIGITAL ASSUMES NO RESPONSIBILITY FOR THE USE OR  RELIABILITY  OF
!	ITS SOFTWARE ON EQUIPMENT THAT IS NOT SUPPLIED BY DIGITAL.
!
!++
! FACILITY:	RMS
!
! ABSTRACT:
!
!	ASCII contains all routines dealing with I/O to ASCII or LSA
!	files; this includes Line Sequence Number handling routines.
!
! ENVIRONMENT:	User Mode, Interrupts deferred until return
!
! AUTHOR: Ron Lusk , CREATION DATE:  8-Mar-83
!
! MODIFIED BY:
!
!	Ron Lusk, 23-Feb-84 : VERSION 2.0
! 01	-   Rewrite PUTLSN and GETLSN for extended addressing.
! 02	-   Return RFA to user
! 03    -   Implement RB$WAA and RB$WBA
! 441	-   Remove MOVST instruction and replace with ILDB/IDPB loop.
!	    The MOVST has an alarming tendency to insert <NUL>s in the
!	    middle of records when records with leading <NUL>s cross
!	    page boundaries.  Also, CTRL-Z detection is needed for TTY:
! 445	-   In edit 441, check MOVEFLAG before checking if enough
!	    buffer space is left; otherwise, after an RTB error,
!	    we neatly past the end of file to "complete" a partial $GET.
! 457	-   In edit 441, we are checking to see if the remaining space
!	    in the user buffer - 1 is LEQ 0.  It should be LSS 0.
!--

!
! TABLE OF CONTENTS
!
!
!	PUTASCII -- Process $PUT macro for ASCII/LSA file
!       PUTELS -- Write End-of-Line sequence to file
!	PUTLSN -- Write LSN to LSA file
!	GETASCII -- Process $PUT macro for ASCII/LSA file
!	GETLSN -- Read LSN from LSA file
!
!
! INCLUDE FILES:
!

REQUIRE 'rmsreq';

!
! MACROS:
!
!   None.
!
! EQUATED SYMBOLS:
!

GLOBAL BIND
    asciv = 2^24 + 0^18 + 441;			! Edit number

!
!   Symbols used for Line-sequenced files
!

LITERAL
    pagemarkcode = -1,				! Line-number for page mark
    pagemarksize = 2*5,				! # of chars in page-mark
    pmrecsize = 2,				! Size of data in page mark
    linenumflag = 1^0,				! Flag to denote line-number
    lsnbufsize = %O'200',			! Size of a TOPS-10 buffer!A56
    pagemark1 = 				! 5 spaces, LSB set
	%EXACTSTRING (5, %O'40') + linenumflag,
    pagemark2 = %CHAR ($chcrt, $chffd);		! <CR><FF><NUL><NUL><NUL>

!
! OWN STORAGE:
!
!   NONE
!
! EXTERNAL REFERENCES:
!
!   None
!
%SBTTL 'PUTASCII -- $PUT for STM and LSA'

GLOBAL ROUTINE putascii : NOVALUE =

!++
! FUNCTIONAL DESCRIPTION:
!	This routine processes the $PUT macro for ASCII and Line-Sequenced
!	ASCII files.  It is placed in this module in order to
!	localize all access to non-RMS file organizations.
!
! FORMAL PARAMETERS
!
!	NONE.
!
! IMPLICIT INPUTS
!
!	?
!
! ROUTINE VALUE:
!
!	NONE.
!
! SIDE EFFECTS:
!
!	?
!
!--

    BEGIN

    LOCAL
	filepointer,				! Byte pointer to file buffer
	userpointer : VECTOR [2],		! Byte pointer to user buffer
						!   (2 words to support
						!   non-zero sections)
	destsize,				! Size of destination buffer
        bytesize,                               ! Bytesize of file        !a577
        bytesperpage,                           ! # of bytes fit on page  !a577
	recordsize,				! Size of current record
	bytestomove,				! Count of bytes to be
						!   moved to user buffer
	asciibytesleft;				! Free bytes in file buffer

    TRACE ('PUTASCII');
    !
    !	If this is a TTY or LPT device, then we must reset all buffer
    !	counters and pointers, etc. If not, we
    !	must make sure that we are at the EOF.
    !

    IF tty OR llpt				![3] Make LPT work
    THEN
	BEGIN					! To reset buffer
	rst [rstbytecount] = 0;			! Clear buffer
	rst [rstpagptr] = CH$PTR (.curentbufferadr);	! Clear buffer
	END
    ELSE
	BEGIN					! To check for EOF
        IF rfaadr                       ! If RFA access                  !a573v
        THEN                            ! Fetch File Page Into User Window
            BEGIN
            rst [Rst$g_Data_Rfa] = .rab [Rab$g_Rfa] ;
            FindAsc( false );
            rst[rst$v_eof]=0;           ! Clear end of file
            END
	ELSE                                                             !a575^
            IF endoffile
	THEN
    !+
    !   Update the RFA put it in the RAB
    !   Since we must be at EOF, the EOF byte # becomes our RFA
    !-
            rab [rabrfa, 0] = rst [rstdatarfa] = .rst [rsthybyte] ! update RFA
        ELSE
	    usererror (er$nef)			! Must be at EOF
	END;

    !+
    !   Update the RFA put it in the RAB
    !   Since we must be at EOF, the EOF byte # becomes our RFA
    !-

    rab [rabrfa, 0] = rst [rstdatarfa] = .rst [rsthybyte];	![2] update RFA
    !
    !   If RB$WAA, advance (or whatever ELS contains) first
    !

    IF (.rab [rabrop, 0] AND rb$waa) NEQ 0	![3]
    THEN
	putels ();

    !
    !	For sequenced files, we must first create a line number.
    !

    IF sequenced
    THEN
	BEGIN
	putlsn ();				! Write LSN into file

	IF .rab [rablsn, 1] EQL pagemarkcode	! NOTE: Extend the sign
	THEN
	    RETURN 				! Ignore record if pagemark
	    					! is output
	END;

    !+
    !	Set up file and user buffer pointers
    !-


    userpointer = .Rab[Rab$a_Rbf];      ! User's Ptr to buffer            !a575
    bytesize = .Fst[Fst$h_Bsz];                                           !a575
    bytesperpage = ( %BPVAL / .bytesize ) * pagesize;			  !a575
    TGUPointer( userpointer, .bytesize ); ! Make 2-word global if needed  !m575

    recordsize = .rab [Rab$h_Rsz];		! Get # bytes to write


    recordsize = .rab [rabrsz, 0];		! Get # bytes to write

    !+
    !	This is the main loop. It continues until the
    !	entire user record has been written to the file.
    !-

    WHILE .recordsize GTR 0 DO
	BEGIN

	!+
	!   Is our buffer full?
	!-

	IF .rst [rstbytecount] EQL pagesize*asciibytperword	!
	THEN
	    writebuffer ();			! Output full buffer

	filepointer = .rst [rstpagptr];		! Fetch file pointer
	bytestomove = .recordsize;		! Assume that record
						! can fit in file
	asciibytesleft = 			! Assume ASCII file
	pagesize*asciibytperword - .rst [rstbytecount];

	!+
	!   Use the record size or the buffer space left, whichever
	!   is smaller.
	!-

	IF .recordsize GTR .asciibytesleft	!
	THEN
	    bytestomove = .asciibytesleft;	!

	destsize = .bytestomove;		! Assume same size

	!+
	!   Debugging
	!-

	lookat ('	FILEPTR: ', filepointer);
	lookat ('	# BYTES: ', bytestomove);
	lookat ('	ASCII BYTES: ', asciibytesleft);

	!+
	!   Do a Move-String With Left Justification to file
	!-

	BEGIN

	LOCAL
	    usrbp : VECTOR [2],			! Temporary 2-word user ptr
	    filbp : VECTOR [2],			! Temporary 2-word file ptr
	    src_len,				! Temporary source length
	    dst_len;				! Temporary dest. length

	!
	!   Set up for MOVSLJ instruction
	!
	usrbp [0] = .userpointer [0];		! Possible 2-word byte pointer
	usrbp [1] = .userpointer [1];
	filbp [0] = .filepointer;		! Local BP
	src_len = .bytestomove;
	dst_len = .destsize;

	IF moveleft_ea (			! Move the record
		usrbp, 				! Source
		filbp, 				! Destination
		src_len, 			! Size of source
		dst_len) EQL false		! Size of destination
	THEN
	    rmsbug (msgmovestring);		! Move-String failed

	!
	!   Update our file and buffer pointers
	!
	filepointer = .filbp;			! Update pointers
	userpointer [0] = .usrbp [0];
	userpointer [1] = .usrbp [1];
	recordsize = .recordsize - .bytestomove;
	rst [rstpagptr] = .filepointer;		! Update pointer
	END;					! End MOVSLJ block
	!
	!   Update # of bytes left in buffer
	!
	rst [rstbytecount] = .rst [rstbytecount] + .bytestomove;
	END;					! Of WHILE loop

    !
    !   If RB$WBA, advance (or whatever ELS contains) now
    !

    IF (.rab [rabrop, 0] AND rb$wba) NEQ 0	![3]
    THEN
	putels ();

    !+
    !   We have now moved the entire record from the user's buffer
    !   into the internal RMS-20 file buffer.  We must also reset
    !   RSTHYBYTE to reflect the highest byte in the file.
    !-

    IF seqadr                                                        !m575
    THEN
        rst [rst$g_highest_byte] = .rst [rst$g_highest_byte] + .rab [Rab$h_Rsz]
    ELSE
        rst [rst$g_highest_byte] = MAX( .rst [rst$g_highest_byte],
                                        .rab[rab$g_rfa] + .rab [Rab$h_Rsz] ) ;

    !+
    !	If we are writing this record to a terminal, then we
    !	should output it immediately.
    !-

    IF tty OR llpt
    THEN
        BEGIN
        writebuffer ();		                        ! Make LPT work
        Rst[Rst$h_Byte_Count] = 0;                      ! Clear byte count
	rst [rstpagptr] = CH$PTR (.curentbufferadr);	! Reset pointer
        END;                                                           !a577

    RETURN
    END;					! End of PUTASCII
%SBTTL 'PUTELS -- write end-of-line sequence'
GLOBAL ROUTINE putels : NOVALUE =

!++
! FUNCTIONAL DESCRIPTION:
!
!       Output the End-of-line sequence as requested
!
! FORMAL PARAMETERS
!
!	NONE.
!
! IMPLICIT INPUTS
!
!	RAB [ELS]
!       RST
!
! ROUTINE VALUE:
!
!	NONE.
!
! SIDE EFFECTS:
!
!	NONE
!
!--

    BEGIN

    LOCAL
	filepointer,				! Byte pointer to file buffer
	userpointer : VECTOR [2],		! Byte pointer to user buffer
						!   (2 words to support
						!   non-zero sections)
	c;					! Current character

    TRACE ('PUTELS');

    !+
    !	Set up file and user buffer pointers
    !-

    IF .rab [rabels, 0] NEQ 0			! Did user specify end-of-line sequence?
    THEN 					! Yes. use it
	BEGIN

	IF .rmssec EQL 0
	THEN
	    userpointer [0] = CH$PTR (.rab [rabels, 0])	! Get user address
	ELSE
	    BEGIN				! Extended addressing

	    LOCAL
		temp;				! Build pointer here

	    temp<lh> = %O'440700' + %O'40';	! 2-word ASCII byte pointer
	    temp<rh> = 0;
	    userpointer [0] = .temp;
	    temp = .rab [rabels, 0];

	    IF .temp<lh> EQL 0 THEN userpointer [1] = .temp OR .blksec ELSE userpointer [1] = .temp;

	    END

	END
    ELSE
	userpointer = CH$PTR (UPLIT (%CHAR (13, 10, 0)));	! Use CRLF default

    !+
    !	This is the main loop. It continues until the
    !	ELS has been written to the file.
    !-

    WHILE (c = CH$RCHAR_A (userpointer)) NEQ 0 DO 	! Copy until we get a NULL
	BEGIN
	! Is our buffer full?

	IF .rst [rstbytecount] EQL pagesize*asciibytperword THEN writebuffer ();	! Output full buffer

	CH$WCHAR_A (.c, rst [rstpagptr]);	! Write the byte out
	rst [rstbytecount] = .rst [rstbytecount] + 1;	! # of bytes in buffer
	rst [rsthybyte] = .rst [rsthybyte] + 1;	! # of bytes in file
	END;					! Of WHILE loop

    RETURN
    END;					! End of PUTELS
%SBTTL 'PUTLSN -- write LSN to file'
GLOBAL ROUTINE putlsn : NOVALUE =

!++
! FUNCTIONAL DESCRIPTION:
!	This routine takes the sequence number from the user's RAB
!	and inserts it into the file as 5 ASCII digits (with bit 0
!	turned on) followed by a horizontal TAB character.  Note
!	That the first digit is forced to be on a word boundary.
!	Any bytes between the VFE of the last record and the LSN
!	will be nulls.
!
! FORMAL PARAMETERS
!
!	NONE.
!
! IMPLICIT INPUTS
!
!	NONE.
!
! ROUTINE VALUE:
!
!	NONE.
!
! SIDE EFFECTS:
!
!	?
!
!		Format of a LSA record
!		====== == = === ======
!
!	<Five-digit-ASCII-number><Bit-0><TAB><The-data-record><VFE>
!
!
!		Format of a Pagemark
!		====== == = ========
!
!	<Five-ASCII-blanks><Bit-0><CR><FF><Three-nulls>
!
!--

    BEGIN

    LOCAL
	users_lsn,				! User's Line-Sequence-Number
	buffer_lsn : REF VECTOR [2];		! Address on page for LSN

    TRACE ('PUTLSN');
    !
    !	Fetch the line number, extending the sign.
    !
    users_lsn = .rab [rablsn, 1];		! Note sign extension

    !+
    !	Check the range of the LSN
    !-

    IF .users_lsn LSS pagemarkcode OR 		! Less than -1?
	.users_lsn GTR maxlsn			! Greater than 99999?
    THEN
	usererror (er$lsn);			! Don't allow such things

    !+
    !	Check now to see if we have enough room
    !	left on this page to put a whole LSN and
    !	its <TAB>, or a whole pagemark.
    !
    !	This means that there will, on occasion,
    !	be a null word near the end of the page.
    !	This is just fine for SOS and EDIT,
    !	and RMS will accept it as well.
    !-

    BEGIN					! Checking end of page

    LOCAL
	bytes_remaining;			! Free bytes in page

    IF (bytes_remaining = 			!
	(pagesize*asciibytperword) - .rst [rstbytecount]) LSS 10
    THEN
	BEGIN
	!
	!   Increment the number of bytes written to file.
	!
	rst [rstbytecount] = .rst [rstbytecount] + .bytes_remaining;
	rst [rsthybyte] = .rst [rsthybyte] + .bytes_remaining;
	!
	!   Write this buffer to file, getting a new one.
	!
	writebuffer ();				! Output page
	END;

    END;

    !+
    !	Calculate the number of bytes we have to
    !	advance the pointer in order to put it on
    !	a word boundary; then, increment all the counters
    !	and the pointer to allow for that.
    !-

    BEGIN

    LOCAL
	bump_count;				! Bytes to bump the

    						!   counters and pointers by.

    !+
    !	The following expression is complex, but neatly yields
    !	the distance from here to the next word boundary.
    !-

    bump_count = 				!
    (asciibytperword - 				! Difference to next word
    (.rst [rstbytecount] MOD asciibytperword))	! boundary, but turn
    MOD asciibytperword;			! 5 chars into 0.
    !
    !	Adjust the pointer and counters
    !
    rst [rstbytecount] = 			! Bytes on page
    .rst [rstbytecount] + .bump_count;
    rst [rsthybyte] = 				! Bytes written to file
    .rst [rsthybyte] + .bump_count;
    rst [rstpagptr] = 				! Byte pointer
    CH$PLUS (.rst [rstpagptr], .bump_count);
    END;

    !+
    !	Convert the byte pointer into an address on the page.
    !-

    BEGIN
    !
    !	To determine the address of the string referenced by
    !	a word-aligned pointer, increment it by 1.  This
    !	will eliminate any possibility of ambiguity in the
    !	address field.
    !
    buffer_lsn = CH$PLUS (.rst [rstpagptr], 1);	! Get whole pointer
    buffer_lsn = .buffer_lsn<0, %BPADDR, 0>;	! Isolate address field
    END;

    !+
    !	Handle pagemarks and real LSNs appropriately.
    !-

    IF .users_lsn EQL pagemarkcode		! LSN = -1?
    THEN

    !+
    !	Put out a pagemark
    !-

	BEGIN
	buffer_lsn [0] = pagemark1;		! First half
	buffer_lsn [1] = pagemark2;		! Second half
	rst [rstbytecount] = 			! Update bytes on page
	.rst [rstbytecount] + pagemarksize;
	rst [rsthybyte] = 			! Update bytes to file
	.rst [rsthybyte] + pagemarksize;
	rst [rstpagptr] = 			! Update byte pointer
	CH$PLUS (.rst [rstpagptr], pagemarksize);
	END
    ELSE

    !+
    !	Write out the Line Sequence Number
    !-

	BEGIN

	LOCAL
	    number_length,
	    double_ptr : VECTOR [2] INITIAL (0, 0),
	    double_lsn : VECTOR [2] INITIAL (0, 0),
	    ascii_lsn;				! "Buffer" for text LSN

	!+
	!   Convert the user's LSN to ASCII.  If the
	!   conversion fails (and it shouldn't by
	!   now), let the user know.
	!-

	double_lsn [1] = .users_lsn;
	double_ptr [0] = CH$PTR (ascii_lsn);
	number_length = asciibytperword OR 1^35;	! For filling

	IF NOT cvtbdo (				! Convert binary to decimal
		number = double_lsn, 		! LSN to convert to text
		string = double_ptr, 		! Destination pointer
		length = number_length, fill = %C'0')	! Fill with zeroes
	THEN
	    usererror (er$lsn);			! Something went wrong

	buffer_lsn [0] = .ascii_lsn OR linenumflag;	! LSN to output buffer
	!
	!   Set byte pointer and write the <TAB>
	!
	rst [rstpagptr] = 			! Postion byte pointer
	CH$PLUS (.rst [rstpagptr], 5);
	CH$WCHAR_A (%O'11', rst [rstpagptr]);	! Write the <TAB>
	!
	!   Update the remaining counters
	!
	rst [rstbytecount] = 			! Update bytes on page
	.rst [rstbytecount] + 6;
	rst [rsthybyte] = 			! Update bytes to file
	.rst [rsthybyte] + 6;
	END;

    END;					! End of PUTLSN
%SBTTL 'GETASCII -- $GET for STM, LSA files'
GLOBAL ROUTINE getascii (moveflag) =

!++
! FUNCTIONAL DESCRIPTION:
!	This routine processes the $GET macro for files with STM
!	and LSA record format.  For ASCII files, it transfers one
!	record into the user's buffer, where a record is defined as
!	being a stream of ASCII bytes terminated by a Vertical
!	Format Effector.
!
!	For sequenced files, full words will be transferred until
!	the next line-number is found.
!
! FORMAL PARAMETERS
!
!	MOVEFLAG --	Flag for record transfer:
!			    True: move the record ($GET)
!			    False: skip the record (last $GET was partial)
!
! IMPLICIT INPUTS
!
!	?
!
! ROUTINE VALUE:
!
!	Number of bytes in record, or number moved if PARTIALFLAG has been set.
!
! SIDE EFFECTS:
!
!	This routine sets RSTRHSIZE, which is the record header size.
!	For ASCII stream files the size is zero (no record header).
!	For LSA stream files the size is 6 if record begins with an LSN,
!	or 10 if the record is a pagemark.  This field is used by the
!	$TRUNCATE processor to know how much to subtract from
!	RSTDATARFA to find the beginning of the current physical record.
!
!	Note: A logical record is defined as the data the user sees;
!	    a physical record is defined as the record header plus the
!	    user's data.
!
!--

    BEGIN

    LOCAL
	significant_char_seen,			! Saw a non-<NUL> char	!A441
	tty_eof,				! EOF on TTY: (^Z seen)	!A441
	userpointer : VECTOR [2],		! Pointer to user's buffer
	exitflag,				! Flag for leaving the loop
	recordsize,				! Current length of record
	nextword,				! Next file word for LSA files
	movestatus,				! Temporary variable
	buffersize,				! Size of user's buffer
        bytesize;                               ! Byte size to use	!a574 

    TRACE ('GETASCII');

    bytesize = .Fab[Fab$v_Bsz];                                         !a574 

    !+
    !	If unit record device, reset buffer
    !   Otherwise, check for end of file
    !-

    IF tty OR llpt				![3] Make LPT work
    THEN
	BEGIN					! To reset buffer
	rst [rstbytecount] = 0;			! Clear buffer
	rst [rstpagptr] = CH$PTR (.curentbufferadr,	! Clear buffer
                                  ,
                                  .bytesize );    ! File byte size        !m574
	END
    ELSE
	BEGIN

	IF endoffile THEN usererror (er$eof);

	END;

    !+
    !	Set up user buffer pointer, etc.
    !-

    userpointer = .Rab[Rab$a_Rbf];      				!a574 
    TGUPointer( userpointer, .bytesize );        			!a574 

    buffersize = 				! Remember size of his buffer
     .rab [Rab$h_Usz] * ( %BPVAL / .Fab[Fab$v_Bsz] ); ! in bytes
    recordsize = 0;				! Clear total size
    rab [Rab$h_Rsz] = 0;			! Clear his record size
    tty_eof = 0;				! Clear TTY: EOF flag	!A441
    exitflag = false;				! Loop forever
                                                                        !d574
    significant_char_seen = 0;			! Skip leading <NUL>s	!A441
    tty_eof = 0;				! Clear TTY: EOF flag	!A441
    exitflag = false;				! Loop forever

    !+
    !	If we are skipping a record, then don't use a user pointer
    !-

    IF .moveflag EQL false THEN userpointer = 0;	! No data will be moved

    !+
    !	Process LSN if reading an LSA stream file.
    !   LSA stream files have 7 bit bytes,
    !   no matter what the FDB says.
    !-

    IF sequenced AND (partialflag EQL 0)
    THEN
	BEGIN					! Get an LSN
	getlsn ();				! Fetch the line-number

	IF .rab [rablsn, 1] EQL pagemarkcode
	THEN
	    BEGIN				! Handle pagemark
	    rst [rstrhsize] = stmrhpm;		! Set record header size
	    setflag (rst [rstflags], flgupdptr);	! Must update pointer
	    rst [rstrsz] = asciibytperword;	! Record size=5

	    IF .buffersize NEQ 0
	    THEN
		BEGIN				! Move the pagemark record
		CH$WCHAR_A (charcr, userpointer);
		CH$WCHAR_A (charff, userpointer);
		END;

	    RETURN pmrecsize			! So, recordsize is zero
	    END
	ELSE
	    rst [rstrhsize] = stmrhlsn		! Set record header size
	END;

    IF NOT (sequenced)				!
    THEN
	rst [rstrhsize] = stmrhasc;		! Set record header size

    						! for ascii stream file

    !+
    !	This is the main loop. it continues until a VFE is
    !	Seen or the user's buffer is filled.
    !-

    UNTIL .exitflag DO
	BEGIN

	!+
	!   If buffer is empty, then re-fill it.
	!-

	IF .rst [rstbytecount] EQL 0 THEN readbuffer ();

	IF endoffile THEN usererror (er$eof);	! Check for EOF

	!+
	!   We will now move the entire record
	!   until we come to either the end
	!   of the file, or the end of the
	!   user's buffer, or a VFE. We will save
	!   the status of this move because we
	!   have to do some common clean-up before
	!   we need to check it.
	!-

	BEGIN

	!++
	!   Beginning of edit 441 rewrite
	!--


	REGISTER 				!			!A441
	    user_ptr_index;			! Index to byte pointer	!A441

	user_ptr_index = userpointer;		! Set index register	!A441

	!+								!A441
	!   This loop copies as much of the record as
	!   is in this file buffer.  If we encounter a
	!   VFE, set MOVESTATUS to FALSE and exit the
	!   loop.  Otherwise, exit when we have
	!   emptied the file buffer or filled 
	!   the user buffer.
	!
	!   If we are reading from the TTY:, regard ^Z
	!   as a terminator like a VFE.
	!
	!-

	movestatus = true;			! Set no-VFE status	!A441

	WHILE .rst [rstbytecount] GTR 0 DO	! While bytes in buffer	!A441
	    BEGIN

	    REGISTER
		char;

	    char = CH$RCHAR_A (rst [rstpagptr]);
	    rst [rstbytecount] = .rst [rstbytecount] - 1;

	    SELECTONE .char OF
		SET

		[$chnul] :
		    BEGIN

		    IF .significant_char_seen	! Seen non-<NUL> already?
		    THEN
			BEGIN

			IF .moveflag AND 	! Quit if moving data	!M445
			(buffersize = .buffersize - 1) LSS 0	! Space	!M457
			THEN
			    EXITLOOP;		! No - leave

			idpb (char, 0, user_ptr_index);	! Yes - put byte
			recordsize = .recordsize + 1;	! Bump size
			END;

		    END;

		[$chlfd, $chvtb, $chffd] :
		    BEGIN

		    IF .moveflag AND 		! Quit if moving data	!M445
		    (buffersize = .buffersize - 1) LSS 0	! Space	!M457
		    THEN 			!
			EXITLOOP;		! No - leave

		    idpb (char, 0, user_ptr_index);	! Yes - put byte
		    recordsize = .recordsize + 1;	! Bump rec size
		    movestatus = false;		! Terminate
		    EXITLOOP;			! Quit looping
		    END;

		[$chcnz] :
		    BEGIN

		    significant_char_seen = 1;

		    IF .moveflag AND 		! Quit if moving data	!M445
		    (buffersize = .buffersize - 1) LSS 0	! Space	!M457
		    THEN 			!
			EXITLOOP;		! No - leave

		    idpb (char, 0, user_ptr_index);	! Yes - put byte
		    recordsize = .recordsize + 1;	! Bump rec size

		    IF tty			! EOF for TTY:?
		    THEN
			BEGIN
			tty_eof = true;		! Yes -
			movestatus = false;	! Terminate
			EXITLOOP;		! Quit looping
			END;

		    END;

		[OTHERWISE] :
		    BEGIN

		    significant_char_seen = 1;

		    IF .moveflag AND 		! Quit if moving data	!M445
		    (buffersize = .buffersize - 1) LSS 0	! Space	!M457
		    THEN 			!
			EXITLOOP;		! No - leave

		    idpb (char, 0, user_ptr_index);	! Yes - put byte
		    recordsize = .recordsize + 1;	! Bump rec size
		    END;
		TES;

	    END;

	!++
	!   End of edit 441 rewrite
	!--

	END;					! End record reading loop

	IF .movestatus EQL false THEN exitflag = true;	! Exit from loop

!++
!
!   At this point, we have done the following:
!
!	1) moved a full record, or
!	2) filled the user's buffer, or
!	3) exhausted the current file buffer.
!
!--

	!+
	!	Set up the record size field and check for
	!	a record which is too big for the user's buffer.
	!-

	IF .moveflag
	THEN
	    BEGIN
	    rab [rabrsz, 0] = .recordsize;	! Update user's record size

	    !+
	    !	If we are still trying to process the
	    !	record,  but the buffer is full then
	    !	we have filled the user's buffer.
	    !-

	    IF (.exitflag EQL false) AND (.buffersize LEQ 0)
	    THEN
		BEGIN
		usrsts = er$rtb;		! Set partial record
		usrstv = .recordsize;		! Return partial record size
		setflag (rst [rstflags], flgpartial);	! Remember this
		exitflag = true			! Leave
		END

	    END;

	END;

    !+
    !   Store the size of this record in the user's RAB
    !-

    rst [rstrsz] = .recordsize;			! Pass the record size back
    !
    !	Set the RST flag bit which tells FINDASC that
    !	the file pointer (PAGPTR) must be updated before
    !	the next operation can be done.
    !
    setflag (rst [rstflags], flgupdptr);
    !									!A441
    !   Check that we didn't receive EOF from TTY:			!A441
    !									!A441

    IF .tty_eof THEN usererror (er$eof);				!A441

    !
    !	We have now done everything and we can exit.
    !
    RETURN .recordsize
    END;					! End of GETASCII
%SBTTL 'GETLSN -- read an LSN'

GLOBAL ROUTINE getlsn : NOVALUE =

!++
! FUNCTIONAL DESCRIPTION:
!	This routine parses a Line Sequence Number.  The file is
!	assumed to have been positioned to a word boundary by
!	the FINDASC routine.  The TAB following the line number
!	will be stripped off by this routine (see note).  See the PUTLSN
!	routine for the format of an LSA record.  Also note that
!	this routine handles pagemarks (see the PUTLSN routine
!	for the format of a pagemark).
!
!	Note:	If the character following the line number is not a
!		<TAB>, it is part of the record and is not stripped.
!
! FORMAL PARAMETERS
!
!	NONE.
!
! IMPLICIT INPUTS
!
!	?
!
! ROUTINE VALUE:
!
!	NONE.
!
! SIDE EFFECTS:
!
!	?
!
!--

    BEGIN

    LOCAL
	buffer_lsn : REF VECTOR [2];		! LSN in input buffer

    TRACE ('GETLSN');

    !+
    !	If there are fewer than five bytes remaining in
    !	the buffer, then the buffer is empty as far
    !	as we are concerned.
    !-

    IF .rst [rstbytecount] LSS asciibytperword
    THEN
	BEGIN
	!
	!   Get a new buffer and check for EOF.
	!
	readbuffer ();				! Get a buffer

	IF endoffile THEN usererror (er$eof);	! EOF wins an error

	END;

    !+
    !	Calculate the number of bytes to the next
    !	word boundary, and adjust the pointer
    !	and counters appropriately.
    !-

    BEGIN

    LOCAL
	aligned_pointer,			! Build pointer here
	bytes_to_bump;				! Bytes to next word

    aligned_pointer = .rst [rstpagptr];		! Copy the buffer pointer
    buffer_lsn = .aligned_pointer<0, %BPADDR>;	! Fetch the address field

    !+
    !	Certain word-aligned pointers (for instance, the
    !	default pointer to an address generated by the POINT
    !	pseudo-op in MACRO) have an address field which
    !	references the beginning of a string, and byte
    !	address fields describing a field to the left of
    !	that string (so an ILDB will get the first byte of
    !	the string, for instance).  If this is the case,
    !	then the address field points to the correct
    !	address.  Other word-aligned pointers contain the
    !	address of the word preceding the word really
    !	pointed to.  This ambiguity has to be checked here.
    !-

    IF .aligned_pointer<30, 6> EQL %O'44' OR 	! Local pointer
	.aligned_pointer<30, 6> EQL %O'61'	! One-word global
    THEN
	buffer_lsn = .aligned_pointer<0, %BPADDR>
    ELSE
	buffer_lsn = .aligned_pointer<0, %BPADDR> + 1;

    aligned_pointer = CH$PTR (.buffer_lsn);	! Set up word-aligned pointer
    !
    !	Fix the counters
    !
    bytes_to_bump = CH$DIFF (.rst [rstpagptr], .aligned_pointer);
    rst [rstpagptr] = .aligned_pointer;
    rst [rstbytecount] = .rst [rstbytecount] - .bytes_to_bump;
    END;

    !+
    !	EDIT and SOS both write a word of nulls at the end
    !	of a block of 200 (octal) words rather than split
    !	the Line Sequence Number and its <TAB> between
    !	blocks.  RMS does the same on page boundaries.  If
    !	we find a word of nulls, it better be on a block
    !	boundary; we'll bump things normally if so, give an
    !	error if not.
    !-

    IF .buffer_lsn [0] EQL 0			! Word of nulls?
    THEN
	BEGIN

	!+
	!   We have three courses of action conditioned
	!   on the position of the null word.
	!-

	SELECTONE 1 OF
	    SET

	    [(.buffer_lsn MOD %O'1000') EQL %O'777'] :
		!
		!   The null is on a page boundary,
		!   so read in another buffer.
		!
		BEGIN
		!
		!   Set up the RFA
		!
		rst [rstdatarfa] = .rst [rstdatarfa] + asciibytperword;
		readbuffer ();			! Get a buffer

		IF endoffile THEN usererror (er$eof);

		!
		!   The buffer address is in the current
		!   bucket descriptor in the RST.  Fetch it
		!   to point at the LSN, rather than finding
		!   what the page pointer is really pointing
		!   to.
		!
		buffer_lsn = .cbd [bkdbktadr];	! Address of new buffer
		END;

	    [(.buffer_lsn MOD %O'200') EQL %O'177'] :
		!
		!   We are on a block boundary that is not a
		!   page boundary (or we would have gotten
		!   caught in the previous select-action.
		!   Bump the pointers to the next block.
		!
		BEGIN
		!
		!   Set up the RFA
		!
		rst [rstdatarfa] = .rst [rstdatarfa] + asciibytperword;
		!
		!   Decrement the number of
		!   bytes left in this buffer.
		!
		rst [rstbytecount] = .rst [rstbytecount] - asciibytperword;
		!
		!   Bump byte pointer.
		!
		rst [rstpagptr] = CH$PLUS (.rst [rstpagptr], asciibytperword);
		!
		!   Adjust pointer to the LSN
		!
		buffer_lsn = .buffer_lsn + 1;
		END;

	    [OTHERWISE] :
		BEGIN
		fileproblem (er$lsn);		! File consistency bug
		usrerr ();			! Take error return
		END;
	    TES;

	END;					! End handling null words

    !+
    !	Handle pagemarks and real LSNs differently.
    !-

    IF .buffer_lsn [0] EQL pagemark1		! Pagemark in file?
    THEN
	BEGIN					! Pagemark handling

	!+
	!   Check to see if we span pages.
	!-

	IF .rst [rstbytecount] EQL asciibytperword	! End of buffer?
	THEN
	    BEGIN				! Pagemark across pages
	    readbuffer ();			! Get a new buffer

	    IF endoffile THEN usererror (er$eof);

	    !
	    !	Adjust pointers to skip
	    !	second word of pagemark.
	    !
	    rst [rstbytecount] = .rst [rstbytecount] - asciibytperword;
	    rst [rstpagptr] = CH$PLUS (.rst [rstpagptr], asciibytperword);
	    END
	ELSE
	    BEGIN				! Normal pagemark
	    !
	    !	Adjust pointers to skip
	    !	over pagemark.
	    !
	    rst [rstbytecount] = .rst [rstbytecount] - pagemarksize;
	    rst [rstpagptr] = CH$PLUS (.rst [rstpagptr], pagemarksize);
	    END;

	!
	!   Update byte position in file
	!
	rst [rstdatarfa] = .rst [rstdatarfa] + pagemarksize;
	!
	!   Return -1 for a pagemark
	!
	rab [rablsn, 1] = pagemarkcode;		! Return -1 as LSN
	END					! Pagemark handling
    ELSE
	BEGIN					! LSN handling

	!+
	!   Convert the linenumber to binary.
	!-

	BEGIN					! LSN conversion

	LOCAL
	    number_length,
	    double_number : VECTOR [2] INITIAL (0, 0),
	    double_pointer : VECTOR [2] INITIAL (0, 0);

	number_length = asciibytperword;
	double_pointer [0] = .rst [rstpagptr];

	IF NOT cvtdbo (				! Convert the number
		number = double_number, 	!
		length = number_length, 	!
		string = double_pointer)	!
	THEN
	    BEGIN
	    fileproblem (er$lsn);		! Something wrong with file
	    usrerr ();				! Tell user
	    END
	ELSE
	    rab [rablsn, 1] = .double_number [1];	! LSW of result

	END;					! LSN conversion
	!
	!   Presumably, all has gone OK so far, so
	!   bump the bytepointer and decrement the
	!   number of bytes remaining on the page.
	!
	rst [rstpagptr] = CH$PLUS (.rst [rstpagptr], asciibytperword);
	rst [rstbytecount] = .rst [rstbytecount] - asciibytperword;
	rst [rstdatarfa] = .rst [rstdatarfa] + asciibytperword;

	!+
	!   If the LSN was (by chance) on the end of a page,
	!   we have to read a new buffer.
	!-

	IF .rst [rstbytecount] EQL 0		! End of page?
	THEN
	    BEGIN
	    readbuffer ();			! Get a new buffer

	    IF endoffile THEN usererror (er$eof);

	    END;

	!+
	!   Look for a <TAB>.  If there is no <TAB>,
	!   then the first character is really part
	!   of a record.  If there is a <TAB>, strip
	!   it off the record.
	!-

	IF CH$RCHAR (.rst [rstpagptr]) EQL $chtab	! Is it a <TAB>?
	THEN
	    BEGIN
	    !
	    !	Skip over <TAB>
	    !
	    rst [rstpagptr] = CH$PLUS (.rst [rstpagptr], 1);
	    !
	    !	Account for the <TAB>
	    !
	    rst [rstbytecount] = .rst [rstbytecount] - 1;
	    rst [rstdatarfa] = .rst [rstdatarfa] + 1;
	    END;

	END;					! LSN handling

    ! [2] RFA will be returned to user before this has fiddled with it
    ! because FINDASC will have set it.
    END;					! End of GETLSN

END						! End of Module ASCII

ELUDOM