; /////////////////////////////////////////////////////////////
; // Window Interface Module
; // (c) 1999 Geoff Knagge, Andrew Carr, Mark Lynn
; // last modified : 22/10/1999
; //
; // Supporting Website :
; // http://members.xoom.com/gogogeoff/uni/elec270/
; //
; /////////////////////////////////////////////////////////////

WinData:
		; status :	bit 7 = 1 if in secure state
		; 		bits 3-0 = controlling zone

	.byte 02H ; Window 1 status
	.byte 01H ; Window 2 status
	.byte 08H ; Window 3 status
	.byte 08H ; Window 4 status
	.byte 08H ; Window 5 status
	.byte 08H ; Window 6 status
	.byte 08H ; Window 7 status
	.byte 08H ; Window 8 status


;//////////////////// Data Accessor Routines

SWgopen:	; get window open status
		; input : C = window number, 
		; output: A = zero if locked
	push hl
	push bc
	mvi b,0
	lxi hl,SW_Masks
	dad bc		; point to right cell
	mov a,m		; read masking info

	lxi hl,SW_open	; point to lock info
	ana m		; get the bit

	pop bc
	pop hl
	ret



SWgCtZone:	; Gets the controlling zone in A
		; input : C = window number, 0 = window 1
		; output: A = zone number
	push bc
	push hl
	push de

	mvi b,0
	lxi hl,WinData	;point HL to the Window array
	dad bc		;move to correct array element
	mov a,m		;load old zone data
	ani 0F		;clear other data

	pop de
	pop hl
	pop bc
	ret


;//////////////////// IO Routines

SW_Masks: .byte 01,02,04,08,10,20,40,80
SW_open: .byte 0	; window open bits in

SW_read:	; read window open statuses
	push af
	in WinPort
	sta SW_open
	pop af
	ret


;//////////////////// Data Modifying Routines

SW_T2Secure:	; Try to secure a window. Input: C=window
		; if it is closed, then secure it
	push af
	call SWgOpen
	cpi 0		; check what's left over
	jnz SWeT2Secure	; not zero, therefore open
	call SW_Secure	; closed, so secure it
SWeT2Secure:
	pop af
	ret

SW_Alarm:	; Check a window - if it's open and secure, give alarm
		; input : C = window number, 0 = window 1
		; output: A = FF if security violated, 00 otherwise
	push bc
	push hl
	call SWgSecure
	cpi 00		; is it set?
	jz SWeAlarm	; no, window isn't classed as secure
			; yes, now check if it's open
	call SWgOpen
	cpi 0		
	jz SWeAlarm	; if 00, window is closed and no alarm
	mvi A,0FF		; set alert code
SWeAlarm:	
	pop hl
	pop bc
	ret

SW_CtZone:	; Sets a window's controlling zone
		; input : C = window number, 0 = window 1
		;	  A = zone number, only bits 3-0 used
	push af
	push bc
	push hl
	push de

	mvi b,0
	lxi hl,WinData	;point HL to the Window array
	dad bc		;move to correct array element

	ani 0F		;masks the other bits
	mov e,a		;E = controlling zone
	mov a,m		;load old zone data
	ani 0F0		;clear old controlling zone
	add e		;add in the new data
	mov m,a		;save it

	pop de
	pop hl
	pop bc
	pop af
	ret
		

SW_secure:	; sets a window to its secure state
		; input : C = window number, 0 = window 1
	push af
	push bc
	push hl
	mvi b,0
	lxi hl,WinData	;point HL to the Window array
	dad bc		;move to correct array element
	mov a,m		;get the status byte
	ori 80		;set secure bit
	mov m,a		;store the new status byte
	pop hl
	pop bc
	pop af
	ret

SWgsecure:	; gets a windows secure state
		; input : C = window number, 0 = window 1
		; output: A= state
	push bc
	push hl
	mvi b,0
	lxi hl,WinData	;point HL to the Window array
	dad bc		;move to correct array element
	mov a,m		;get the status byte
	ani 80		;get secure bit
	pop hl
	pop bc
	ret

SWgLock:	; is a window (zone) locked?
	push hl
	push de
	push bc
	call SWgCtZone
	call SZgLock
	pop bc
	pop de
	pop hl
	ret

SW_unsecure:	; resets a windows secure state
		; input : C = window number, 0 = window 1
	push af
	push bc
	push hl
	mvi b,0
	lxi hl,WinData	;point HL to the window array
	dad bc		;move to correct array element
	mov a,m		;get the status byte
	ani 7F		;clear secure bit
	mov m,a		;store the new status byte
	pop hl
	pop bc
	pop af
	ret