*-----------------------------------------------------------
* Program Number: Forritunarverkefni 4
* Written by    : Sævar Öfjörð Magnússon
* Date Created  : 2005-04-09
* Description   :
*-----------------------------------------------------------

GETNUM	MACRO
	move.b	#4,d0	; get user guess in D1.L
	trap	#15
	ENDM

GETCHAR	MACRO
	move.b	#5,d0
	trap	#15
	ENDM

PRINT	MACRO		; macro til að prenta stærri texta
	lea	\1,a1	; hlaða inn addressu
	move.b	#14,d0	; trap kóði
	trap	#15
	ENDM

CLS	MACRO			; macro til að hreinsa display
	move.l	#$FF00,D1	
	move.b	#11,D0
	trap	#15		; clear display	
	ENDM

	ORG	$800
SPACE	equ	$20		; space
CR	equ	$0d		; carriage return
LF	equ	$0a		; line feed
newline	dc.b	CR,LF,0
selkey	dc.b	'Select a key to execute a function: ',0
enternum	dc.b	'Enter a number (0-65535): ',0
displist	dc.b	'The list contains: ',0
adgerdir	dc.b	'Functions: (I)nsert item - (D)elete item - '
	dc.b	'(E)mpty list - (Q)uit',CR,LF,CR,LF,0
quitmsg	dc.b	'Are you sure you want to quit? (Y/N) ',0
delmsg	dc.b	'Enter the number you wish to delete: ',0
errempty	dc.b	'The list is empty',CR,LF,CR,LF,0
error1	dc.b	'ERROR: The list is full, try to delete items'
	dc.b	' before inserting.',CR,LF,CR,LF,0
error2	dc.b	'ERROR: The item you were trying to delete is '
	dc.b	'not in this list. Try again.',CR,LF,CR,LF,0
listemptied	dc.b	'List has been emptied. It contained: ',0
LIMIT	equ	$1FF0

START	ORG	$1000
	move	#$203C,LIMIT
	move	#0,A2
	move	#$2000,A3
MAIN	CLS
	bsr	HEADER
MAIN2	PRINT	selkey
	GETCHAR
	and	#$DF,D1		; breytum í hástaf
	cmp.b	#$44,D1		; athugum hvort það sé D
	beq	OKDELETE
	cmp.b	#$45,D1		; athugum hvort það sé E
	beq	OKEMPTY
	cmp.b	#$51,D1		; athugum hvort það sé Q
	beq	OKQUIT
	cmp.b	#$49,D1		; athugum hvort það sé I
	beq	OKINSERT
	bra	MAIN

OKDELETE	bsr	DELETION
	bra	MAIN
OKEMPTY	bsr	EMPTY
	bra	MAIN2
OKINSERT	bsr	INSERTION
	bra	MAIN
OKQUIT	bsr	QUIT
	bra	MAIN
ERRORFULL	CLS
	bsr	HEADER
	PRINT	error1
	bra 	MAIN2
ERROREXIST	CLS
	bsr	HEADER
	PRINT	error2
	bra	MAIN2

*********************************************
 HEADER:
*********************************************
	PRINT	adgerdir
	PRINT	displist
	bsr	PRENTALISTA
	rts

*********************************************
 INSERTION:
*********************************************
	CLS
	bsr	HEADER
	PRINT	enternum
	GETNUM
	cmp	LIMIT,A3
	bge	ERRORFULL
	move	D1,(A3)
	cmp	#0,A2	; athuga hvort haus sé núll (listi tómur)
	bgt	HEAD
	move	A3,A2	; setja adressu á nýrri færslu í haus
	add	#$6,A3	; hækkum pointer um 6
	move	A2,A6	; setjum hausinn í bendi á fyrri færslu
	rts
HEAD	move	(A3),D3
	cmp	(A2),D3	; athugum hvort nýja færsla verði haus	
	bge	SEARCH	; ef ekki þarf að leita
	move	A2,4(A3)
	move	A3,A2
	add	#$6,A3
	move	A2,A6	; setjum hausinn í bendi á fyrri færslu
	rts
SEARCH	move	A2,A4	; Afritum hausbendi í leitarbendi
	move	a2,a6
LOOP1	move	4(A4),A5	; afritum addressu á næstu færslu í a5
	cmp	#0,A5	; athugum hvort þetta sé endir á lista
	beq	TAIL
	cmp	(A5),D3
	ble	INSERT
	move	A5,A4
	add	#6,A6
	bra	LOOP1
INSERT	move	A4,A6
	move	A5,4(A3)
	move	A6,2(A3)
	move	A3,4(A4)
	move	A3,2(A5)
TAIL	move	A3,4(A4)
	move	A6,2(A3)
	move	A4,A6	; setjum teljarann í bendi á fyrri færslu
	add	#$6,A3
	rts

*********************************************
 DELETION:
*********************************************
	CLS
	bsr	HEADER
	PRINT	delmsg
	GETNUM
	cmp	(A2),D1	; bera saman við tölu sem eyða á
	bgt	SEARCH2
	move	4(A2),A2
	rts
SEARCH2	move	A2,A4
LOOP3	cmp	#0,A4
	beq	ERROREXIST
	move	4(A4),A5
	move	2(A4),A6
	cmp	(A5),D1
	beq	DELETE
	move	A5,A4
	bra	LOOP3
DELETE	move	4(A5),A1
	move	A1,4(A4)
	move	2(A5),A6
	move	A6,2(A1)
	add	#6,LIMIT
	rts

*********************************************
 PRENTALISTA:
*********************************************
	move	A2,A4
	cmp	#0,A2	; er listi tómur?
	bne	LOOP2
	PRINT	errempty
	move	#$2000,A3
	move	#0,A2
	rts
LOOP2	move	(A4),D1
	move	#3,D0
	trap	#15
	move.b 	#6,D0 	; trap kóði 6
	move.b 	#$20,D1 	; setjum stafabil í d1
	trap 	#15 	; birtum það sem er í D1
	move	4(A4),A5
	move	A5,A4
	cmp	#0,A5
	bne	LOOP2
	PRINT	newline
	PRINT 	newline
	rts

*********************************************
 EMPTY:
*********************************************
	CLS
	PRINT	adgerdir
	PRINT	listemptied
	move	A2,A4
LOOP4	move	4(A4),A5
	move	(A4),D1
	move	#3,D0
	trap	#15
	move.b 	#6,D0 	; trap kóði 6
	move.b 	#$20,D1 	; setjum stafabil í d1
	trap 	#15 	; birtum það sem er í D1
	move	#0,2(A4)
	move	#0,4(A4)
	move	A5,A4
	cmp	#0,A4
	bne	LOOP4
	
	PRINT	newline
	PRINT	newline

	move	#$2000,A3
	move	#0,A2
	move.l	#0,(A3)
	move	#0,4(A3)
	rts

*********************************************
 QUIT:
*********************************************
	CLS		; hreinsa skjáinn
	bsr	HEADER
	PRINT	quitmsg	; spyrja hvort notandi vilji hætta
	move.b	#5,D0	; biðja um einn staf (trap kóði)
	trap	#15	; biðjum um já eða nei
	and	#$DF,D1	; breytum í hástaf
	cmp.b	#$59,D1	; athugum hvort það sé Y
	beq	END	; hættum alveg keyrslu ef Y
	cmp.b	#$4e,D1	; athugum hvort það sé N
	rts

END	MOVE.B	#9,D0
	TRAP	#15		Halt Simulator

	END	START
*~Font name~Courier New~
*~Font size~10~
*~Tab type~1~
*~Tab size~12~