%TITLE 'CHMDELCHR - delete characters'
MODULE CHMDELCHR (				! Delete characters
		IDENT = '3-002'			! File: CHMDELCHR.BLI Edit: GB3002
		) =
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:
!
!	This module deletes text on the current line (change mode).
!
! ENVIRONMENT:	Runs at any access mode - AST reentrant
!
! AUTHOR: Bob Kushlis, CREATION DATE: Unknown
!
! MODIFIED BY:
!
! 1-001	- Original.  DJS 04-Feb-1981.  This module was created by
!	extracting the routine DELETE_CHARS from module CHANGE.BLI.
! 1-002	- Regularize headers.  JBS 27-Feb-1981
! 1-003	- Fix module name.  JBS 03-Mar-1981
! 1-004	- Improve some comments.  JBS 02-Jun-1981
! 1-005	- New screen update logic.  JBS 13-Sep-1982
! 1-006	- Change the call to EDT$$MRK_LCNHG.  JBS 27-Dec-1982
! 3-001 - Change CPY_MEM to CPY_STR.  GB 3-Mar-1983
! 3-002 - Add updates from V3 sources.  GB 26-Apr-1983
!--

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

REQUIRE 'EDTSRC:TRAROUNAM';

FORWARD ROUTINE
    EDT$$DEL_CHS : NOVALUE;			! Delete part of the current line

!
! INCLUDE FILES:
!

REQUIRE 'EDTSRC:EDTREQ';

!
! MACROS:
!
!	NONE
!
! EQUATED SYMBOLS:
!
!	NONE
!
! OWN STORAGE:
!
!	NONE
!
! EXTERNAL REFERENCES:
!
!	In the routine
%SBTTL 'EDT$$DEL_CHS  - delete characters'

GLOBAL ROUTINE EDT$$DEL_CHS (			! Delete characters
		FC, 					! Position of first character to delete
		LC					! Position of last character to delete
   	 ) : NOVALUE =

!++
! FUNCTIONAL DESCRIPTION:
!
!	This routine deletes text on the current line between the
!	two pointers FC and LC.
!
! FORMAL PARAMETERS:
!
!  FC			Position of the first character to delete
!
!  LC			Position of the last character to delete
!
! IMPLICIT INPUTS:
!
!	SEL_POS
!	LN_END
!
! IMPLICIT OUTPUTS:
!
!	SEL_POS
!	LN_PTR
!
! ROUTINE VALUE:
!
!	NONE
!
! SIDE EFFECTS:
!
!	NONE
!
!--

    BEGIN

    EXTERNAL ROUTINE
	EDT$$MRK_LNCHG : NOVALUE,		! Track line update bounds
	EDT$$UPD_LNLEN : NOVALUE,		! Update the length of the current line
	EDT$$SAV_LN : NOVALUE,			! Save a line in the auxiliary buffer
	EDT$$SEL_RNGPOS;			! Compare the select line with the current line

    EXTERNAL
	SEL_POS,				! select position.
	LN_END,					! End of current line pointer
	LN_PTR,					! Current character pointer
	LN_BUF;					! Line buffer

    LOCAL
	LEN;

!+
! Compute length of the delete, and quit if zero.
!-
    LEN = CH$DIFF (.LC, .FC);
    EDT$$SAV_LN (.FC, .LEN);

    IF (.LEN EQL 0) THEN RETURN;

!+
! Watch out for select range, adjust as necessary.
!-

    IF (EDT$$SEL_RNGPOS () EQL 0)
    THEN
!+
! This is the selected line
!-

	IF CH$PTR_GTR (.SEL_POS, .FC)
	THEN

	    IF CH$PTR_GTR (.SEL_POS, .LC)
	    THEN
		SEL_POS = CH$PLUS (.SEL_POS, -.LEN)
	    ELSE
		SEL_POS = .FC;

!+
! Now, adjust the line.
!-
    EDT$$CPY_STR (CH$DIFF (.LN_END, .LC), .LC, .FC);
    EDT$$UPD_LNLEN (-.LEN);
    EDT$$MRK_LNCHG (SCR_EDIT_MODIFY, CH$DIFF (.FC, CH$PTR (LN_BUF)));
    LN_PTR = .FC;
    END;			! of routine EDT$$DEL_CHS

END				! of Module CHMDELCHR
ELUDOM