;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;			A U T O T O G
;			  for ZPM3
;			by Simeon Cran
;			   30/3/92
;
; This program toggles the Auto Command Prompting facility of ZPM3. It is
; presented in source code form to inform users about how the facility is
; manipulated.

; Be aware that when Auto Command Prompting is enabled with this program,
; it won't actually operate until turned on at the keyboard with ^Q. This
; program simply enables the ^Q toggling of Auto Command Prompting.

; When ZPM3 is booted, Auto Command Prompting is disabled. Usually, a
; startup file would include the AUTOTOG command to turn it on unless it
; is felt that the facility could confuse the operator (as may happen with
; a remote ZPM3 system).
;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

; SYNTAX:
;  AUTOTOG	Toggles the state of the Auto Command Prompting
;  AUTOTOG ON	Enables Auto Command Prompting
;  AUTOTOG OFF	Disables Auto Command Prompting
;  AUTOTOG //	Displays a brief help message

;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;
; Automatic Command Prompting is enabled and disabled by a bit 6 of offset
; 85h of the SCB page. This offset can not be directly accessed by the SCB
; function (31h). Instead, we get the SCB base page with function 31h, and
; then find the offset from there. No other bits in the byte may be touched.
;
;===============================================================================

BDOS	equ	5
deffcb	equ	5ch
SCBfunc	equ	31h	; Get/Set SCB function number
SCBoff	equ	3bh	; Offset in SCB to get SCB base page
ACPoff	equ	85h	; Offset in SCB base page of Auto Command Prompting bit

	jp	start	; Jump over general data

HELPmsg:
	db	' SYNTAX:'
	db	10,13
	db	'  AUTOTOG	Toggles the state of the Auto Command Prompting'
	db	10,13
	db	'  AUTOTOG ON	Enables Auto Command Prompting'
	db	10,13
	db	'  AUTOTOG OFF	Disables Auto Command Prompting'
	db	10,13
	db	'  AUTOTOG //	Displays a brief help message'
	db	'$'
ONmsg:
	db	'ZPM3 Auto Command Prompting is now enabled. Toggle with ^Q.'
	db	'$'
OFFmsg:
	db	'ZPM3 Auto Command Prompting is now disabled.'
	db	'$'

ONword:	; Word to match to turn Auto Command Prompting on
	db	'ON      '
OFFword:	; Word to match to turn Auto Command Prompting off
	db	'OFF     '
TOGword:	; Word to match to toggle Auto Command Prompting
	db	'        '

HELP:	ld	de,HELPmsg
MSGexit:
	ld	c,9
	call	bdos
	rst	0

start:	; Get the address of the bit which controls Auto Command Prompting.
	ld	c,SCBfunc
	ld	de,SCBPB
	call	bdos		; Get base page of SCB
	ld	h,a
	ld	l,ACPoff	; HL is now the address of the byte
	ld	(ACPaddr),hl	; Save it	

; Find out what the user wants to do. If the argument matches
;  any of the three control words, act accordingly, otherwise
;  show the help message and exit.
	ld	hl,ONword
	call	matchWord
	jr	z,TurnON
	ld	hl,OFFword
	call	matchWord
	jr	z,TurnOFF
	ld	hl,TOGword
	call	matchWord
	jr	nz,HELP
; Toggle the Auto Command Prompting.
	ld	hl,(ACPaddr)
	bit	6,(hl)
	jr	z,TurnON
TurnOFF:	; Turn the Auto Command Prompting off.
	ld	hl,(ACPaddr)
	res	6,(hl)
	ld	de,OFFmsg
	jr	MSGexit	

TurnON:		; Turn the Auto Command Prompting on.
	ld	hl,(ACPaddr)
	set	6,(hl)
	ld	de,ONmsg
	jr	MSGexit



matchWord:	; Compare the string at HL with the string at defFCB+1 for
		;  8 bytes. Return Z if it matches.
	ld	de,defFCB
	ld	bc,8
matchW1:
	inc	de
	ld	a,(de)
	cpi
	ret	nz
	jp	pe,matchW1
	ret
	
SCBPB:	; System control block function parameter block.
ACPaddr:	; Save the address of the ACP bit here too.
	db	03bh
	db	0		; Get operation