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 %TITLE 'UGBUFFER - get a buffer pointer'
MODULE UGBUFFER (				! Get a buffer pointer
		IDENT = '3-002'			! File: UGBUFFER.BLI Edit: CJG3002
		) =
BEGIN
!COPYRIGHT (c) DIGITAL EQUIPMENT CORPORATION 1981, 1988.  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:	EDT -- The DEC Standard Editor
!
! ABSTRACT:
!
!	Get a buffer pointer.  Create a buffer if necessary.
!
! ENVIRONMENT:	Runs at any access mode - AST reentrant
!
! AUTHOR: Bob Kushlis, CREATION DATE: February 7, 1978
!
! MODIFIED BY:
!
! 1-001	- Original.  DJS 19-FEB-1981.  This module was created by
!	extracting routine EDT$$GET_BUFPTR  from module UTIL.
! 1-002	- Regularized headers.  JBS 25-Feb-1981
! 1-003	- Fix module name.  JBS 11-Mar-1981
! 1-004 - Implement virtual memory deallocation TMV 6-Aug-81
! 1-005	- When a buffer is first allocated we are positioned at
!	   its front.  JBS 08-Apr-1982
! 3-001 - Make arguments to CH$EQL into string ptrs for Tops10/20.  GB 27-Jan-1983
! 3-002 - NAME is already a pointer - don't make it one again. CJG 24-Mar-83
!--

%SBTTL 'Declarations'
!
! TABLE OF CONTENTS:
!

REQUIRE 'EDTSRC:TRAROUNAM';

FORWARD ROUTINE
    EDT$$GET_BUFPTR;

!
! INCLUDE FILES:
!

REQUIRE 'EDTSRC:EDTREQ';

!
! MACROS:
!
!	NONE
!
! EQUATED SYMBOLS:
!
!	NONE
!
! OWN STORAGE:
!
!	NONE
!
! EXTERNAL REFERENCES:
!
!	In the routine
%SBTTL 'EDT$$GET_BUFPTR  - get a buffer pointer'

GLOBAL ROUTINE EDT$$GET_BUFPTR (		! Get a buffer pointer
    NAME, 					! Pointer to buffer name
    LEN, 					! Length of that name
    BUF_ADDR, 					! Place to store buffer address
    NEW						! 1 = new buffer created
    ) =

!++
! FUNCTIONAL DESCRIPTION:
!
!	This routine searches for a buffer with a specified name.  If the buffer
!	if found, then the address of the TBCB is returned.  If the buffer is not
!	found, then a buffer by that name is created.
!
! FORMAL PARAMETERS:
!
!  NAME			Pointer to a string containing the name of the buffer.
!
!  LEN			Length of the name string.
!
!  BUF_ADDR		Address of a fullword to receive the TBCB address.
!
!  NEW			Address of a flag to be set if the buffer was newly created.
!
! IMPLICIT INPUTS:
!
!	BUF_LST
!
! IMPLICIT OUTPUTS:
!
!	BUF_LST
!
! ROUTINE VALUE:
!
!	Returns zero if an attempt to create a new buffer failed, one otherwise.
!
! SIDE EFFECTS:
!
!	May create a new buffer and link it onto the buffer list.
!
!--

    BEGIN

    EXTERNAL ROUTINE
	EDT$$ALO_HEAP;

    EXTERNAL
	BUF_LST : REF TBCB_BLOCK,	! Pointer to first buffer in line.
	LNO_ZERO : LN_BLOCK;		! Clear line number

    LOCAL
	NEW_BUF : REF TBCB_BLOCK;

!+
! Start with the head of the text buffer list.
!-
    NEW_BUF = .BUF_LST;
!+
! Now link our way through the list until we either find a matching
! name or hit the end of the list.
!-

    WHILE (.NEW_BUF NEQ 0) DO

	IF CH$EQL (.LEN, .NAME, .NEW_BUF [TBCB_NAME_LEN],
			 CH$PTR (NEW_BUF [TBCB_NAME],, BYTE_SIZE))
	THEN
	    EXITLOOP
	ELSE
	    NEW_BUF = .NEW_BUF [TBCB_NEXT_BUF];

    IF (.NEW_BUF EQL 0)
    THEN
	BEGIN
!+
! Well, we didn't find it.  Better create a new one.
!-

	IF ( NOT EDT$$ALO_HEAP (%REF (TBCB_SIZE*BYTES_PER_WORD + .LEN), NEW_BUF)) THEN RETURN (0);

	NEW_BUF [TBCB_NAME_LEN] = .LEN;
!+
! Move the name into the newly created text buffer.
!-
	CH$MOVE (.LEN, .NAME, CH$PTR (NEW_BUF [TBCB_NAME],, BYTE_SIZE));
!+
! And append it to the front of the buffer list.
!-
	NEW_BUF [TBCB_NEXT_BUF] = .BUF_LST;
	NEW_BUF [TBCB_PREV_BUF] = 0;

	IF (.BUF_LST NEQ 0) THEN BUF_LST [TBCB_PREV_BUF] = .NEW_BUF;

	BUF_LST = .BUF_ADDR = .NEW_BUF;
!+
! Initialize the other fields in the TBCB.
!-
	NEW_BUF [TBCB_LINE_ADDR] = 0;		! Pointer to current line.
	NEW_BUF [TBCB_CUR_BUKT] = 0;		! Current bucket number.
	MOVELINE (LNO_ZERO, NEW_BUF [TBCB_CUR_LIN]);	! Current line number.
	NEW_BUF [TBCB_CHAR_POS] = 0;		! The character position within the line
	NEW_BUF [TBCB_FIRST_BUKT] = 0;		! First bucket number.
	NEW_BUF [TBCB_LAST_BUKT] = 0;		! Last bucket number.
	MOVELINE (LNO_ZERO, NEW_BUF [TBCB_INPUT_LINE]);	! Number of last input line.
	MOVELINE (LNO_ZERO, NEW_BUF [TBCB_LINE_COUNT]);	! Count of lines in buffer.
	NEW_BUF [TBCB_CHAR_COUNT] = 0;		! Count of chars in buffer.
	NEW_BUF [TBCB_INPUT_RAB] = 0;		! Pointer to input RAB.
	NEW_BUF [TBCB_IS_MAC] = 0;
	.NEW = 1;
	END
    ELSE
	.NEW = 0;

    .BUF_ADDR = .NEW_BUF;
    RETURN (1);
    END;					! of routine EDT$$GET_BUFPTR


END
ELUDOM