page	, 132
	title	PL/M Application Startup Code
	subttl	Copyright (c) 2011-2012,2018-2020, the ACME Software Deli

; ============================================================================
;   This program is distributed in the hope that it will be useful, but
;   WITHOUT ANY WARRANTY; without even the implied warranty of
;   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE
;
;   Permission to use for any purpose, modify, copy, and make enhancements
;   and derivative works of the software is granted if attribution is given to
;   R.M. Gillmore, dba the ACME Software Deli, as the author
;
;   While the ACME Software Deli does not work for money, there is nonetheless a
;   a significant amount of work involved.  The ACME Software Deli maintains the
;   rights to all code written, though it may be used and distributed as long as
;   the following conditions are maintained.
;
;   1.  The copyright statement at the top of each code block is maintained in
;       your distribution.
;   2.  You do not identify yourself as the ACME Software Deli
;   3.  Any changes made to the software are sent to the ACME Software Deli
; ============================================================================
	page

	name	startSup
	.186

protectedData	segment	public	'Data'
	programSegmentSelector	Dw	?
	programSegmentOffset	Dw	?
protectedData	ends

plmLibrary_Code	segment	public	'Code'
ifndef SMALL
	db	'@(#)startSup.a86  $Author: rmgillmore $ $Date:: 2025-05-04 19:35:39#$:', 0
endif
plmLibrary_Code	ends

stack	segment	public 'Stack'
stack	ends

memory	segment	public	'Memory'
;	memoryVar	dw	?
memory	ends

plmLibrary_Data	segment	public	'Data'
	decimalString	db	15 dup (?)
plmLibrary_Data	ends

	plmLibrary_CGroup	group	plmLibrary_Code
	plmLibrary_DGroup	group	plmLibrary_Data

plmLibrary_Code	segment	public	'Code'

	plmLibrary_CGroup	group	plmLibrary_Code

	assume	Cs:plmLibrary_CGroup

; --------------------------------------------------------------------------------
; Function:	storePSP / getPSP
;
; store / retrieve the address of the initial program segment prefix (really
; more of a program header).
; --------------------------------------------------------------------------------

	public	storePSP

storePSP	proc	far

;	we MUST be careful not to modify ES register since that is the selector
;	in the PSP address

	push	Ds
	mov	Ax, seg programSegmentSelector
	mov	Ds, Ax
	assume	Ds:protectedData
	mov	Ax, Es
	mov	programSegmentSelector, Ax
	xor	Ax, Ax
	mov	programSegmentOffset, Ax
	pop	Ds
	ret
storePSP	endp

	public	getPSP

getPSP	proc	far
	push	Ds
	mov	Ax, seg programSegmentSelector
	mov	Ds, Ax

	assume	Ds:protectedData

	mov	Dx, programSegmentSelector
	mov	Ax, programSegmentOffset
	pop	Ds
	ret
getPSP	endp

; --------------------------------------------------------------------------------
; Function:	initializeDataArea
;
; Initialize the data area with zeroes (making it a lot like the starting
; environment for a C application)
; --------------------------------------------------------------------------------

WORDS_PER_PARA	equ	8	; a paragraph is this many words

	public	initializeDataArea

; _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*-_
;
;  if the segment/group order is different than noted at the top of this module,
;  this may not work, and perhaps even cause undesirable events (like a crash)
;
; _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*- _-*-_

initDataArea_Params	struc
	init_oldFrame	Dw	?
	rtnAddress	Dd	?
	startingSegment	Dw	?
initDataArea_Params	ends

initializeDataArea	proc	far
	push	Bp
	mov	Bp, Sp

	; the starting segment for the clearing is placed in DX by the caller

	mov	Dx, [Bp].startingSegment
	mov	Bx, stack		; the starting segment for "do not touch"
	xor	Ax, Ax			; we want to store zero in every word

clearSegment:
	cmp	Dx, Bx			; are we at the end?
	jge	doneClearing		; if so, break out of the loop
	mov	Es, Dx			; the destination address is ES:DI
	xor	Di, Di
	mov	Cx, WORDS_PER_PARA
	rep	stosw
	inc	Dx			; next paragraph, please
	jmp	clearSegment

doneClearing:
	pop	Bp
	ret
initializeDataArea	endp

plmLibrary_Code	ends
	end