; Input appended to this code:
; [4 arbitrary bytes] [byte-prefixed pstring] [padding to even byte] ... [4 bytes] [zero byte]

; Outputs: D0 = index of selected string, Ao = pointer to selected string

_BoundaryLabelAtStartOfBootPicker_

; Aesthetic parameters
.kMinWid	equ 70		; min width to leave for button label
.kBtnHt		equ 20		; should always be 20 because text won't move
.kBtnGap	equ 13
.kPadX		equ 5+26	; due to border, padding=6 would leave 1 white pixel
.kPadY		equ 5+13


; Save all the stuff that we whack
		movem.l	A1-A5/D1-D7,-(SP)
		move.l	$3F8,-(SP)			; Save DSAlertRect
		move.l	$3F8+4,-(SP)
		move.l	$9CE,-(SP)			; Save ToolScratch
		move.l	$9CE+4,-(SP)
		move.l	$2BA,-(SP)			; Save DSAlertTab
		move.l	$A8C,-(SP)			; Save RestProc
		move.l	$120,-(SP)			; Save MacJmp
		move.b	$BFF,-(SP)			; Save MacJmpFlag (32-bit only)
		link.w  A6,#0				; We use a lot of stack


; Head-patch _PtInRect to account for our unusual window placement
		move.w	#$A8AD,D0			; _PtInRect
		dc.w	$A146				; _GetTrapAddress
		move.l	A0,$9CE+4			; Save in ToolScratch+4 to enable head-patch

		move.w	#$A8AD,D0			; _PtInRect
		lea		.MyPtInRect,A0
		dc.w	$A047				; _SetTrapAddress


; Do the usual "QuickDraw outside of application" setup
		clr.l	-(SP)
		move.l	SP,A5				; tiny A5 world with QD globals ptr
		lea		-206(SP),SP			; push the QD globals
		pea		202(SP)
		dc.w	$A86E				; _InitGraf
		dc.w	$A8FE				; _InitFonts (because we use _StringWidth)
		lea		-108(SP),SP
		pea		(SP)
		dc.w	$A86F				; _OpenPort (don't save, we have our own globs)


; Copy a stub alert table to the stack
		move.l	#.MyDSAlertTabEnd-.MyDSAlertTabStart,D0
		sub.l	D0,SP
		move.l	SP,A1
		lea		.MyDSAlertTabStart,A0
		dc.w	$A22E ; _BlockMoveData


; First pass: calculate box width, putting shortest string width into D5
		moveq.l	#.kMinWid,D5
		bsr		.GetA0								; A0 = current pstring ptr
.dswLoop
		tst.b	(A0)
		beq.s	.dswDone

		move.l	A0,-(SP)
		clr.w	-(SP)
		move.l	A0,-(SP)
		dc.w	$A88C								; _StringWidth
		move.w	(SP)+,D0
		addq.w	#8,D0
		cmp.w	D0,D5
		bgt.s	.notlargest
		move.w	D0,D5
.notlargest
		move.l	(SP)+,A0

		bsr		.AdvanceA0
		bra.s	.dswLoop
.dswDone


; Second pass: create a button list object in the DS alert table
		move.w	(SP)+,D7							; pop NumEntries from DS table

		move.l	#((.kPadY)<<16)|(.kPadX),D2			; D2 = current button's topleft
		move.l	#((.kPadY+.kBtnHt)<<16)|(.kPadX+4+4),D3; D3 = current button's botright
		add.w	D5,D3								; ...including width of the text
		moveq.l	#0,D6								; D6 = button counter
		bsr		.GetA0								; A0 = current pstring ptr
.dsbLoop
		tst.b	(A0)
		beq.s	.dsbDone

		move.w	D6,-(SP)							; push procedure object ID (base $8000)
		add.w	#$8000,(SP)
		move.l	D3,-(SP)							; push botright
		move.l	D2,-(SP)							; push topleft
		move.w	D6,-(SP)							; push string object ID (base $C000)
		add.w	#$C000,(SP)
												; increment...
		add.l	#(.kBtnHt+.kBtnGap)<<16,D2			; the button's top edge
		add.l	#(.kBtnHt+.kBtnGap)<<16,D3			; the button's bottom edge
		addq.w	#1,D6								; the button counter
		bsr		.AdvanceA0
		bra.s	.dsbLoop

.dsbDone											; done looping, push a header for this object...
		move.w	D6,-(SP)							; the number of buttons
		mulu	#12,D6								; the size in bytes = 12n+2
		add.w	#2,D6
		move.w	D6,-(SP)
		move.w	#$1993,-(SP)						; the unique ID for this button list

		addq.w	#1,D7
		move.w	D7,-(SP)							; increment and re-push NumEntries


; Third pass: calculate box height
		lea		$3F8,A1								; A0 = DSAlertRect
		move.l	(A5),A0								; From QD globals
		move.l	-122+6+4(A0),D0						; D0 = screenBits.bounds.botRight, so D0.W = screen width

		add.w	#.kPadX,D3							; D3 = box width
		sub.w	D3,D0
		bgt.s	.nottoowide
		clr.w	D0
.nottoowide
		asr.w	#1,D0
		move.w	D0,2(A1)							; set DSAlertRect left
		move.w	D0,$9CE+2							; & stash in ToolScratch for .MyPtInRect
		add.w	D3,D0
		move.w	D0,6(A1)							; set DSAlertRect right

		swap	D0									; D0 = screen height
		swap	D2									; D2 = box height ("top" of next button)
		add.w	#.kPadY-.kBtnGap,D2					; adjust box height
		sub.w	D2,D0
		bgt.s	.nottoohigh
		clr.w	D0
.nottoohigh
		asr.w	#1,D0
		move.w	D0,(A1)								; set DSAlertRect top
		move.w	D0,$9CE								; & stash in ToolScratch for .MyPtInRect
		add.w	D2,D0
		move.w	D0,4(A1)							; set DSAlertRect bottom


; Fourth pass: create a string offset for each button
		moveq.l	#0,D6								; D6 = button counter
		bsr		.GetA0								; A0 = current pstring ptr
.dssLoop
		tst.b	(A0)
		beq.s	.dssDone

		move.w	(SP)+,D7							; pop NumEntries from DS table

													; push the struct fields...
		bsr		.PushPaddedString					; even-length string with 2-byte length
		move.w	D6,-(SP)							; the unique ID (C000+n)
		add.w	#$C000,(SP)

		addq.w	#1,D7
		move.w	D7,-(SP)							; increment and re-push NumEntries

													; increment...
		addq.w	#1,D6								; the button counter
		bsr		.AdvanceA0
		bra.s	.dssLoop
.dssDone


; Fifth pass: generate code for each button
		moveq.l	#0,D6								; D6 = button counter
		bsr		.GetA0								; A0 = current pstring ptr
.dspLoop
		tst.b	(A0)
		beq.s	.dspDone

		move.w	(SP)+,D7							; pop NumEntries from DS table

		pea		.ReturnToCaller						; craft the code for this button...
		move.w	#$4EF9,-(SP)						; jmp .ReturnToCaller (absolute addr)
		move.l	A6,-(SP)
		move.w	#$2C7C,-(SP)						; move.l #CorrectA6,A6 ; frame ptr
		move.l	A0,-(SP)
		move.w	#$207C,-(SP)						; move.l #CorrectA0,A0 ; return string ptr
		move.l	D6,-(SP)
		move.w	#$203C,-(SP)						; move.l #CorrectD0,D0 ; return string idx

													; push a header...
		move.w	#24,-(SP)							; the size in bytes of the above code
		move.w	D6,-(SP)							; the unique ID (8000+n)
		add.w	#$8000,(SP)

		addq.w	#1,D7
		move.w	D7,-(SP)							; increment and re-push NumEntries

													; increment...
		addq.w	#1,D6								; the button counter
		bsr		.AdvanceA0
		bra.s	.dspLoop

.dspDone											; Must clear the instruction cache on 030/040
		move.l	A6,D0
		sub.l	SP,D0
		move.l	SP,A0
		move.l	SP,A1
		dc.w	$A02E								; using non-Data _BlockMove


; Put up the DeepShit alert
		move.l	SP,$2BA								; Set DSAlertTab
		clr.l	$A8C								; Clear RestProc or our buttons get jumbled
		move.w	#$2012,D0							; Our error object number
		dc.w	$A9C9								; _SysError!
		bra.s	*									; Should never return


; The selected procedure will jump to here after setting A6,A0,D0
.ReturnToCaller
		movem.l	A0/D0,-(SP)							; save/restore our return values

		move.l	(A5),A0								; Open a new whole-screen port
		move.l	(A0),-(SP)
		dc.w	$A86F								; _OpenPort

		pea		$3F8								; DSAlertRect
		move.l	(A5),A0								; 
		pea		-24(A0)								; qd.gray
		dc.w	$A8A5								; _FillRect

		move.w	#$A8AD,D0							; Unpatch _PtInRect
		move.l	$9CE+4,A0							; We saved it in ToolScratch
		dc.w	$A047								; _SetTrapAddress

		movem.l	(SP)+,A0/D0

		unlk    A6									; See the saving code for details
		move.b	(SP)+,$BFF
		move.l	(SP)+,$120
		move.l	(SP)+,$A8C
		move.l	(SP)+,$2BA
		move.l	(SP)+,$9CE+4
		move.l	(SP)+,$9CE
		move.l	(SP)+,$3F8+4
		move.l	(SP)+,$3F8
		move.l	#-1,$14A
		movem.l	(SP)+,A1-A5/D1-D7
		rts


.PushPaddedString ; trashes A1-A2,D0-D2, but must preserve A0
		move.l	(SP)+,A2

		move.l	A0,-(SP) ; backup
		moveq.l	#0,D0
		clr.w	-(SP)
		move.l	A0,-(SP)
		dc.w	$A88C ; _StringWidth
		move.w	D5,D0
		sub.w	(SP)+,D0
		bgt.s	.notzero
		moveq.l	#0,D0
.notzero
		asr.w	#3,D0 ; divide the leftover by twice a Chicago space
		move.l	(SP)+,A0 ; restore backup

		clr.w	D1
		move.b	D0,D1
		add.b	(A0),D1
		addq.b	#1,D1
		bclr	#0,D1 ; this is the spaced-out length in memory

		clr.w	D2
.spaceloop
		cmp.w	D2,D1
		beq.s	.spacedone
		move.w	#$2020,-(SP)
		addq.w	#2,D2
		bra.s	.spaceloop
.spacedone
		move.w	D1,-(SP)


		lea		2(SP),A1 ; bm dest
		add.w	D0,A1

		clr.l	D0
		move.b	(A0),D0
		move.l	A0,-(SP)
		addq.l	#1,A0 ; bm src
		dc.w	$A22E ; _BlockMoveData
		move.l	(SP)+,A0


		jmp		(A2)


.MyPtInRect
		move.l	$9CE,D0
		sub.w	D0,10(SP)
		swap	D0
		sub.w	D0,8(SP)

		move.l	$9CE+4,A0
		jmp		(A0)


.GetA0
		lea		.TrailingList+4,A0
		rts


.AdvanceA0
		moveq.l	#1,D0
		add.b	(A0),D0
		add.l	D0,A0
		and.l	#1,D0 ; align to 2-byte boundary
		add.l	D0,A0
		lea		4(A0),A0 ; skip the 4-byte header
		rts


.MyDSAlertTabStart
		dc.w	1		; NumEntries

; Our only alert definition
		dc.w	$2012	; ID of this error
		dc.w	10		; length of remaining items
		dc.w	0		; primary text definition ID
		dc.w	0		; secondary text definition ID
		dc.w	0		; icon definition ID
		dc.w	0		; procedure definition ID
		dc.w	$1993	; button definition ID
.MyDSAlertTabEnd

.TrailingList
_BoundaryLabelAtEndOfBootPicker_