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 %TITLE 'LPUSH - Push to a new EXEC'
MODULE LPUSH     (				! Push to a new EXEC
		IDENT = '3-003'			! File: LPUSH.BLI
		) =
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 executes the PUSH command which transfers
!	control to a new copy of EXEC.
!
! ENVIRONMENT:	Runs at any access mode 
!
! AUTHOR: Chris Gill	CREATION DATE: September 1983
!
! MODIFIED BY:
!
! 3-001 - Creation. CJG 20-Sep-1983
! 3-002 - Keep the subfork after creating it. CJG 8-Dec-1983
! 3-003 - Add EDT$$XDDT_CMD for the XDDT command. CJG 9-Dec-1983
!--

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

REQUIRE 'EDTSRC:TRAROUNAM';

FORWARD ROUTINE
    EDT$$PUSH_CMD : NOVALUE,			! PUSH command
    EDT$$XDDT_CMD : NOVALUE;			! XDDT command

!
! INCLUDE FILES:
!

REQUIRE 'SYS:JSYS';

REQUIRE 'EDTSRC:EDTREQ';

!
! MACROS:
!
!	NONE
!
! EQUATED SYMBOLS:
!
!	NONE
!
! OWN STORAGE:
!
!	NONE
!
! EXTERNAL REFERENCES:
!
!	In the routine

%SBTTL 'EDT$$PUSH_CMD  - Push to a new EXEC'

GLOBAL ROUTINE EDT$$PUSH_CMD 			! Push to a new EXEC
    : NOVALUE =

!++
! FUNCTIONAL DESCRIPTION:
!
!	This routine creates a subfork and places a copy of EXEC in it.
!	It then starts the EXEC and waits for it to exit.
!
! FORMAL PARAMETERS:
!
!	NONE
!
! IMPLICIT INPUTS:
!
!	NONE
!
! IMPLICIT OUTPUTS:
!
!	NONE
!
! ROUTINE VALUE:
!
!	NONE
!
! SIDE EFFECTS:
!
!	Runs a copy of EXEC
!
!--

    BEGIN

    EXTERNAL ROUTINE
	EDT$$TI_WRSTR,			! Used to see which mode we're in
	EDT$$TI_RES : NOVALUE,		! Reset terminal state
	EDT$$TI_OPN : NOVALUE,		! Open the terminal
	EDT$$SC_RESET : NOVALUE,	! Reset the screen
	EDT$$SC_SETWID : NOVALUE,	! Set terminal width
	EDT$$FMT_MSG;			! Print error message

    EXTERNAL
	TXT_ONSCR,			! Text may be on screen
	TT_OPEN,			! Terminal state
	TI_WID,				! Terminal width
	TI_RESET,			! Terminal reset state
	PUSH_FLAG,			! Flag for PUSH command
	FORK_HANDLE,			! Subfork handle
	SCR_CHGD,			! Force update
	SAV_TIWID,			! Terminal width on entry
	FMT_WRRUT;			! Used to see which mode we're in

    MESSAGES ((NOCREFORK, ABNFRKTRM, NOFNDEXEC));

    LOCAL
	FORK_JFN,			! JFN of EXEC
	FORK_STATUS;			! Exit status of subfork

!+
! Create a fork and get SYS:EXEC.EXE into it if not already present.
!-

    IF (.FORK_HANDLE EQL 0)
    THEN
	BEGIN
	IF ( NOT _CFORK (CR_CAP; FORK_HANDLE))
	THEN
	    BEGIN
	    EDT$$FMT_MSG (EDT$_NOCREFORK);
	    RETURN;
	    END;

	IF ( NOT _GTJFN (GJ_OLD + GJ_SHT, 
		CH$PTR (UPLIT (%ASCIZ 'DEFAULT-EXEC:')); FORK_JFN))
	THEN
	    IF ( NOT _GTJFN (GJ_OLD + GJ_SHT, 
		    CH$PTR (UPLIT (%ASCIZ 'SYSTEM:EXEC.EXE')); FORK_JFN))
	    THEN
		BEGIN
		EDT$$FMT_MSG (EDT$_NOFNDEXEC);
		RETURN;
		END;

	IF ( NOT _GET (FLD (.FORK_HANDLE, FLD_LHS) + FLD (.FORK_JFN, FLD_RHS), 0))
	THEN
	    BEGIN
	    EDT$$FMT_MSG (EDT$_NOCREFORK);
	    RETURN;
	    END;

   	END;

!+
! Now reset the terminal to its orriginal state
!-

    IF (.FMT_WRRUT EQL EDT$$TI_WRSTR) THEN EDT$$SC_RESET ();
    IF .TI_RESET THEN EDT$$TI_RES ();
    IF (.TI_WID NEQ .SAV_TIWID) THEN EDT$$SC_SETWID (.SAV_TIWID);
    TT_OPEN = 0;

!+
! Start the fork and wait for it to complete. Then see what the status is
! and kill the fork.
!-

    _SFRKV (.FORK_HANDLE, 0);
    _WFORK (.FORK_HANDLE);
    _RFSTS (.FORK_HANDLE; FORK_STATUS);

!+
! Open the terminal and mark the screen as changed
!-

    EDT$$TI_OPN ();
    IF (.FMT_WRRUT EQL EDT$$TI_WRSTR)
    THEN
	BEGIN
	TXT_ONSCR = 1;
	SCR_CHGD = 2;
	END;

    PUSH_FLAG = -1;
    IF ((.FORK_STATUS AND NOT RF_FRZ) NEQ FLD ($RFHLT, RF_STS)) THEN
	EDT$$FMT_MSG (EDT$_ABNFRKTRM);

    RETURN;

    END;					! of routine EDT$$PUSH_CMD

!<BLF/PAGE>

%SBTTL 'EDT$$XDDT_CMD  - Invoke DDT'

GLOBAL ROUTINE EDT$$XDDT_CMD 			! Invoke DDT
    : NOVALUE =

!++
! FUNCTIONAL DESCRIPTION:
!
!	This routine calls DDT so that breakpoints can be set and 
!	items of EDT's internals examined.
!
! FORMAL PARAMETERS:
!
!	NONE
!
! IMPLICIT INPUTS:
!
!	NONE
!
! IMPLICIT OUTPUTS:
!
!	NONE
!
! ROUTINE VALUE:
!
!	NONE
!
! SIDE EFFECTS:
!
!	Maps DDT into pages 766 to 777 and sets .JBDDT (location 74).
!--

    BEGIN

    EXTERNAL ROUTINE
	EDT$$FMT_STR,				! Output a message
	EDT$$FMT_CRLF,
	EDT$$OUT_FMTBUF,
	EDT$$FMT_MSG;				! Print error message

    LOCAL
	DDT_JFN;				! JFN of SYS:UDDT.EXE

    LITERAL
	JBDDT = %O'74',				! .JBDDT address
	JBSYM = %O'116';			! .JBSYM address

    MESSAGES ((NODDTAVL));

    IF (.JBDDT EQL 0)
    THEN
	BEGIN
	IF ( NOT _GTJFN (GJ_OLD + GJ_SHT,
			 CH$PTR (UPLIT (%ASCIZ 'SYS:UDDT.EXE')); DDT_JFN)) THEN
	    BEGIN
	    EDT$$FMT_MSG (EDT$_NODDTAVL);
	    RETURN;
	    END;

	IF ( NOT _GET (FLD ($FHSLF, FLD_LHS) + GT_PRL + GT_ADR + .DDT_JFN,
		       FLD (%O'766', FLD_LHS) + FLD (%O'777', FLD_RHS))) THEN
	    BEGIN
	    EDT$$FMT_MSG (EDT$_NODDTAVL);
	    RETURN;
	    END;

	JBDDT = %O'770000';			! Set the entry address
	.(%O'770001')<0,18> = .JBSYM;		! Copy the symbol pointer
	END;

    EDT$$FMT_STR (CH$PTR (UPLIT ('Type POPJ P,<ESC>X to return')), 28);
    EDT$$FMT_CRLF ();
    EDT$$OUT_FMTBUF ();

    (.JBDDT)<0,18> ();
    RETURN;
    END;
!<BLF/PAGE>

END						! of module LPUSH
ELUDOM