NEW
  AUTO 3,1
* object code = sel_1
* Bird's Better Bye at org = dispadr
*--------------------------------------
SEL1.START
birdbye			cld
				lda RROMBNK2			read ROM
				stz softev
				lda #$10				set reset vector to 'dispadr'
				sta softev+1
				jsr setpwrc				create power-up byte
				lda #$A0
				jsr $C300			 	initialize 80 column text card
				ldx #$17

* set up memory bitmap in global page

L5D16  			stz MEMTABL,x			P8 memory bitmap
				dex
				bpl L5D16
				inc MEMTABL+$17			protect global page
				lda #$CF				protect zero page, stack and page 1
				sta MEMTABL
				lda #$02
				sta smparms				init set mark parms pcount.

* drive selector

				ldx DEVCNT				get device count and
				stx lstpntr				store in zero page.
				lda devnum			 	get last slot/drive
				bne volname

ds2				ldx lstpntr				get device list pointer.
				lda DEVLST,x			get unit number from list.
				cpx #$01			 	make sure it's real.
				bcs L5D3F			  	if so, change list pointer.
				ldx DEVCNT				get device count.
				inx
L5D3F  			dex		 				decrement list pointer and restore.
				stx lstpntr

* get and store volume name

volname			sta ol_unit				store unit number for online.
				jsr MLI
				.DA #MLIONLINE
				.DA ol_parms
				bcs ds2				  	error check.

				stz dlevel			 	haven't read root directory yet.
				lda pbuf+1				load description byte.
				and #$0F			 	mask for name length.
				beq ds2				  	if 0, then try next unit.
				adc #$02			 	add 2 to length.
				tax		 				name length in x.

vnam1			stx pbuf				save the name length
				lda #$2F			 	'/'
				sta pbuf+1			 	slash before and
				sta pbuf,x			 	after name.
				stz pbuf+1,x			null after complete name.

* open and read directory

				jsr MLI			
			   .DA #MLIOPEN
			   .DA op_parms
				bcc L5D7F				good open.

				lda dlevel			 	trying to open root directory ?
				beq ds2				  	yes, just move to next volume.
				jsr bell1			  	no, generate bell tone
				jsr popdir				and stay at same level.
				stx pbuf
				jmp keyloop

L5D7F  			inc dlevel
				stz filecount			zero file count.
				lda op_refn				get file reference number
				sta rd_refn				store in read
				sta sm_refn				and setmark parm lists.
				lda #$2B			 	set read parm list for
				sta dhdr_len			directory header length.
				stz dhdr_len+1
				jsr doread				read directory
				bcs L5DB3

				ldx #$03

L5D9A  			lda sysentry+$23,x		copy directory info
				sta entlen,x			to zero page.
				dex
				bpl L5D9A

				sta dhdr_len			put entry length in read parm list.
				lda #$01			 	set block file counter to 1.
				sta blkfl
				stz fpos_mid			zero out msb's of file position
				stz fpos_hi				in setmark parm list.
				lda filecnt				any files in directory ?
				ora filecnt+1
				bne L5DB5			  	if so, continue
L5DB3  			bra L5E29			  	else go close directory file.

L5DB5  			bit filecnt+1			check msb of file count.
				bmi L5DB3			  	if set then done.

L5DB9  			lda fpos_mid			get mid byte of setmark file position.
				and #$FE			 	reset lsb
				sta fpos_mid			and save.
				ldy blkfl			  	block file counter
				lda #$00
				cpy entblk			 	have we read all entries in this block ?
				bcc L5DCE				if not, continue.
				tay		 				if so, zero y-reg and
				sty blkfl			  	reset block counter / flag
				inc fpos_mid

* set up setmark parameters for next file to be read.
* if transfer to second sector, handle it.

L5DCC  			inc fpos_mid
L5DCE  			dey						decrement file block counter
				clc
				bmi L5DD8

				adc entlen			 	add entry length to acc.
				bcc L5DCE			  	determine if we flopped into 2nd half of
				bcs L5DCC				block, if so inc mid byte position.

L5DD8  			adc #$04				add 4 and put in
				sta fpos_lo				low byte of setmark.
				jsr MLI					call mli
			   .DA #MLISETMARK
			   .DA #smparms				parameters address = $0060
				.HS 00
				bcs L5DB3				error

				jsr doread
				bcs L5DB3			  	error.

				inc blkfl			  	increase count of files read.
				lda sysentry			file type/length.
				and #$F0			 	mask off high nibble.
				beq L5DB9			  	deleted file, try next one.
				dec filecnt				decrement low file count.
				bne L5DF8
				dec filecnt+1			and high if necessary.

L5DF8  			ror sysentry+$1E		check access bit.
				bcc L5DB5			  	if no read, try next file.
				lda sysentry+$10		get file type.
				cmp #$0F			 	directory file ?
				beq L5E08			  	then continue.
				cmp #$FF			 	system file ?
				bne L5DB5			  	no, read next file.

L5E08  			ldx filecount			get valid files read.
				cpx #$80			 	if greater than size of filename buffer
				bcs L5E29			  	then close directory
				sta filetyps,x			else store filetype in zero page
				jsr namecalc			and go set up storage area.
				ldy #$0F

L5E15  			lda sysentry,y			get byte of filename
				sta (fnstore),y			store in directed area
				dey
				bpl L5E15

				iny		 				y = 0
				and #$0F			 	mask off low nibble (name length)
				sta (fnstore),y			restore in name buffer
				inc filecount			increment valid file counter
				bne L5DB5			  	get next file (branch always)

L5E26  			jmp ds2			  		error. try next unit.

L5E29  			jsr MLI					close directory file
			   .DA #MLICLOSE
			   .DA cl_parms
				bcs L5E26				error.

				jsr settxt			 	use full screen for windows
				jsr home
				lda #$17			 	cursor at bottom of screen.
				jsr TABV				set vertical position.
				ldy #$00
				lda #$14			 	horizontal position.
				jsr sethorz				print message.
				jsr homecurs			cursor to upper/left.

				ldx #$00

L5E48  			lda pbuf+1,x
				beq showfiles
				jsr output
				inx
				bne L5E48

showfiles 		stz	valcnt
				stz topname				init top filename index.
				lda filecount			# of valid files.
				beq keyloop			  	if no files.
				cmp #$15			 	more than what will fit on screen ?
				bcc L5E61			  	no.
				lda #$14			 	limit to 20 files on the screen.
L5E61  			sta gp_cnt
				lda #$02				set window dimensions
				sta wndtop
				sta wndlft
				lda #$16
				sta wndwdth
				sta wndbtm
L5E6F  			jsr nameprnt			output filename to screen
				inc valcnt
				dec gp_cnt			 	file counter.
				bne L5E6F			  	continue printing names.
				stz valcnt
				beq L5EAA			  	if last file, it needs to be inverse.
uparrow			jsr	nameprnt			print old name in normal.
				ldx valcnt			 	get old name number.
				beq L5EAA			 	if already at the top name
				dec valcnt			 	else fix index.
				lda cv			   		current cursor line.
				cmp #$02			 	at top line of window ?
				bne L5EAA			  	no, move up normally.
				dec topname				fix offset index
				lda #$16			 	else sroll windows down a line.
				bne L5EA7			  	branch always.
dnarrow			jsr	nameprnt			print old name in normal.
				ldx valcnt			 	get old name number.
				inx		 				add one.
				cpx filecount
				bcs L5EAA			  	if already at last filename
				stx valcnt			 	else update index.
				lda cv			   		current cursor line.
				cmp #$15			 	at bottom line of window ?
				bne L5EAA			  	no, move cursor normally.
				inc topname				update offset index
				lda #$17			 	else scroll up a line.
L5EA7  			jsr cout
L5EAA  			jsr setinv			 	set inverse text mode.
				jsr nameprnt			output last filename.
keyloop			lda kbd			  		get keyboard input.
				bpl keyloop			  	loop until key pressed.
				sta KBDSTROBE			clear strobe.
				jsr setnorm				set normal text mode.
				ldx filecount			are any files displayed ?
				beq L5ECB			  	no, don't accept arrow keys or return.
				cmp #$8D			 	return ?
				beq L5EF4			  	then run selected file.
				cmp #$8A			 	down ?
				beq dnarrow				move down a name.
				cmp #$8B			 	up ?
				beq uparrow				move up a name.
L5ECB  			cmp #$89			 	tab ?
				beq L5EED			  	new volume.
				cmp #$9B			 	esc ?
				bne keyloop			  	no, try again else pop up a directory.

* pop a directory level

				jsr popdir
				dec dlevel
				bra L5EF1

popdir			ldx pbuf

L5EDD  			dex
				lda pbuf,x
				cmp #$2F				slash
				bne L5EDD

				cpx #$01
				bne L5EEC

				ldx pbuf
L5EEC  			rts

L5EED  			jmp ds2					set up new unit number.

L5EF0  			inx

L5EF1  			jmp vnam1			  	get new directory info.

* run selected file

L5EF4  			jsr MLI	
			   .DA #MLISETPREFIX
			   .DA pf_parms
				bcs L5EED				error.

				ldx valcnt			 	get name number.
				jsr namecalc			set up name storage area (on return y=0)

				ldx pbuf			 	get prefix length.

L5F04  			iny		 				start at y = 1.
				lda (fnstore),y			get character of name.
				inx
				sta pbuf,x			 	store in prefix buffer.
				cpy namelen				check length of name.
				bcc L5F04			  	loop until all transferred.

				stx pbuf			 	put prefix length into buffer.
				ldy valcnt			 	get file number.
				lda	filetyps,y			get file type.
				bpl L5EF0			  	branch if directory.

				jsr settxt			 	reset to full window.
				jsr home			 	makes for no flash.
				lda #$95			 	ctrl-u
				jsr cout			 	turn off 80 columns.

				jsr MLI					open file
			   .DA #MLIOPEN
			   .DA op_parms
				bcs L5EED			  	if error.

				lda op_refn				move reference number
				sta rd_refn				for read.
				lda #$FF			 	read the entire file.
				sta dhdr_len
				sta dhdr_len+1
				jsr doread			 	read selected file.
				php		 				save possible error.
				jsr MLI					close file. ignore any error from close
			   .DA #MLICLOSE
			   .DA cl_parms
				plp		 				restore status from read.
				bcs L5EED			  	if any errors.
				jmp sysentry			execute selected system file.

* output messages. on entry: acc = horizontal position,
* y = index to message teminated by 0.

sethorz			sta ch
msgout			lda dsp2msg,y
				beq L5F57
				jsr cout
				iny
				bne msgout
L5F57  			rts

* name pointer calculator for name storage area

namecalc 		stz fnstore+1			init high byte of 16-bit shift
				txa
				asl			 			shift to high nibble
				rol fnstore+1
				asl
				rol fnstore+1
				asl
				rol fnstore+1
				asl
				rol fnstore+1
				sta fnstore				low pointer
				lda /iobuf
				clc
				adc fnstore+1
				sta fnstore+1
				ldy #$00
				lda (fnstore),y			file name length
				sta namelen
				rts

* output a filename line

nameprnt 		lda #$02
				sta ch80col				horizontal position = 2.
				ldx valcnt			 	filename number
				txa
				sec
				sbc topname				calculate line # to display name
				inc
				inc
				jsr TABV				set vertical position.
				lda filetyps,x			get filetype (x is unchanged by tabv).
				bmi L5F99			  	branch if system file.
				stz ch80col				adjust cursor position.
				lda invflg				ave current inverse setting
				pha
				ldy #fldrmsg-dsp2msg
				jsr msgout			 	display the folder.
				pla		 				restore inverse setting.
				sta invflg

L5F99  			jsr outsp				output a space.
				jsr namecalc			calc name location.

L5F9F  			iny		 				y = 1 (first time).
				lda (fnstore),y			get name character.
				jsr output			 	put on screen.
				cpy namelen				end of name ?
				bcc L5F9F			  	no.

outsp			lda #$A0
				bne L5FB1			  	branch always.

homecurs 		lda #$99
output			ora #$80			 	set high bit.
L5FB1  			jmp cout			 	output to screen.

doread			jsr MLI					mli read call
			   .DA #MLIREAD
			   .DA rd_parms
				rts

* data area

dsp2msg			.AS -"RETURN: Select | TAB: Chg Vol | "
				.AS -"ESC: Back"
				.DA #$00

fldrmsg			.DA #$0F				inverse control code
				.HS 1B			 		enable mousetext
				.AS -"XY"				folder characters
				.HS 18			  		disable mousetext
				.HS 0E			  		normal control code
				.HS 00

op_parms 		.DA #$03			  	3 parms
				.DA pbuf				pathname
				.DA op_buf				file buffer
op_refn			.HS 00					reference number

cl_parms 		.HS 01			  		1 parm
				.HS 00					reference number.

ol_parms 		.HS 02					2 parms
ol_unit			.HS 60					unit number, default = s6, d1
				.DA pbuf+1				data buffer

pf_parms 		.DA #01		  			one parm
				.DA pbuf				pathname

rd_parms 		.DA #04			  		4 parms
rd_refn			.HS 01					reference number
				.DA sysentry			data buffer

* these last 2 parms (4 bytes) may extend past $300 length limit since
* the request count is set prior to using the parm block and the transfer
* count isn't used at all (except by prodos)
				.DUMMY
				.BS 2					requested length
				.BS 2					actual length
dhdr_len 		.BS 1					directory header length (actually uses 2 bytes)
				.ED
*--------------------------------------
SEL1.LEN		.EQ *-SEL1.START
MAN
SAVE USR/SRC/PRODOS.FX/PRODOS.S.SEL1
LOAD USR/SRC/PRODOS.FX/PRODOS.S
ASM
