Google
 

Trailing-Edge - PDP-10 Archives - tops20-v7-ft-dist1-clock - 7-sources/mcleft.bli
There are 10 other files named mcleft.bli in the archive. Click here to see a list.
 %TITLE 'MCLEFT - move cursor left'
MODULE MCLEFT (				! Move cursor left
		IDENT = '1-002'			! File: MCLEFT.BLI Edit: JBS1002
		) =
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:
!
!	Move cursor left.
!
! ENVIRONMENT:	Runs at any access mode - AST reentrant
!
! AUTHOR: Bob Kushlis, CREATION DATE: September 9, 1979
!
! MODIFIED BY:
!
! 1-001	- Original.  DJS 19-FEB-1981.  This module was created by
!	extracting routine EDT$$CS_LEFT  from module MOVCUR.
! 1-002	- Regularize headers.  JBS 11-Mar-1981
!--

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

REQUIRE 'EDTSRC:TRAROUNAM';

FORWARD ROUTINE
    EDT$$CS_LEFT;

!
! INCLUDE FILES:
!

REQUIRE 'EDTSRC:EDTREQ';

!
! MACROS:
!
!	NONE
!
! EQUATED SYMBOLS:
!
!	NONE
!
! OWN STORAGE:
!
!	NONE
!
! EXTERNAL REFERENCES:
!
!	In the routine
%SBTTL 'EDT$$CS_LEFT  - move cursor left'

GLOBAL ROUTINE EDT$$CS_LEFT 			! Move cursor left
    =

!++
! FUNCTIONAL DESCRIPTION:
!
!	This routine moves the cursor one character to the left.  If the cursor
!	is on the first character of the line, we move to the previous line
!	(positioning on the line terminator).
!
! FORMAL PARAMETERS:
!
!	NONE
!
! IMPLICIT INPUTS:
!
!	LN_BUF
!	LN_END
!
! IMPLICIT OUTPUTS:
!
!	LN_PTR
!
! ROUTINE VALUE:
!
!	1 = move successful
!	0 = could not move
!
! SIDE EFFECTS:
!
!	NONE
!
!--

    BEGIN

    EXTERNAL ROUTINE
	EDT$$CS_UP;

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

!+
! Check to see if we are on the first character.
!-

    IF CH$PTR_EQL (.LN_PTR, CH$PTR (LN_BUF,, BYTE_SIZE))
    THEN
	BEGIN
!+
! On the first character.  Try to go up a line and position to the line
! terminator.  If the move up fails, return failure.
!-

	IF (EDT$$CS_UP () EQL 0) THEN RETURN (0);

	LN_PTR = .LN_END;
	END
    ELSE
!+
! Not on the first character, simply move back on character and return
! success.
!-
	LN_PTR = CH$PLUS (.LN_PTR, -1);

    RETURN (1);
    END;


END
ELUDOM