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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) 1981, 1985 BY
!	      DIGITAL EQUIPMENT CORPORATION, MAYNARD, MASS.
!		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 WHICH 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