A2osX/ProDOS.FX/ProDOS.S.XDOS.B.txt

NEW
  AUTO 3,1

* create file

create			jsr lookfile			check for duplicate, get free entry
				bcs tstfnf				error code may be 'file not found'
				lda #MLI.E.DUPFILE		name already exists
crerr1			sec
				rts

tstfnf			cmp #MLI.E.FNOTFND		'file not found' is ok
				bne crerr1				otherwise exit with error.

				ldy #$07				test for tree or directory file,
				lda (A3L),y				no other kinds are legal.
				cmp #$04				is it seed, sapling or tree?
				bcc tstdspc				branch if it is

				cmp #$0D
				bne ctyperr				report type error if not directory.

tstdspc			lda devnum				make sure destination device
				jsr twrprot1			is not write protected.
				bcs H351D

				lda nofree				is there space in directory to
				beq xtndir				add this file? branch if not
				jmp creat1				otherwise, go create file.

ctyperr			lda #MLI.E.UNSUPST		filetype error
				sec
H351D  			rts

xtndir			lda own_blk				before extending directory,
				ora own_blk+1			make sure it's a subdirectory.
				bne H352A

				lda #MLI.E.DIRFULL		otherwise, directory full error
				sec
				rts
	
H352A  			lda bloknml				preserve disk address of current (last)
				pha						directory link, before allocating an
				lda bloknml+1			extended block.
				pha
				jsr alc1blk				allocate a block for extending directory
				plx
				stx bloknml+1			restore block addr of dir info in gbuf
				plx
				stx bloknml
				bcs H351D				unable to allocate.

				sta gbuf+2				save block address in y,a to
				sty gbuf+3				current directory.
				jsr wrtgbuf				update directory block with new link.
				bcs H351D				if error

				ldx #$01

swpbloks 		lda bloknml,x			prepare new directory block
				sta gbuf,x				using current block as back link
				lda gbuf+2,x
				sta bloknml,x			and save new block as next to be written
				dex
				bpl swpbloks
				inx
				txa						x and a = 0

clrdir 			sta gbuf+2,x
				sta gbuf+$100,x
				inx
				bne clrdir

				jsr wrtgbuf				write prepared directory extension.
				bcs H351D				if error

				lda own_blk
				ldx own_blk+1
				jsr rdblk				read in parent directory block
				ldx own_ent				and calc entry address.
				lda /gbuf
				sta zpt+1
				lda #$04
ocalc  			clc
				dex						has entry address been calulated?
				beq H3584				if yes.
				adc own_len				next entry address
				bcc ocalc
				inc zpt+1				entry must be in 2nd 256 bytes of block
				bcs ocalc				always taken.

H3584  			sta zpt
				ldy #$13				index to block count
H3588  			lda (zpt),y
				adc dinctbl-$13,y		add 1 to block count and
				sta (zpt),y
				iny
				tya						$200 to the directory's eof.
				eor #$18				done with usage/eof update?
				bne H3588				branch if not.

				jsr wrtgbuf				go update parent.
				bcs crerr2

				jmp create
crerr2 			rts						return and report errors

creat1			ldx #$00				zero out gbuf
H35A0  			stz gbuf,x
				stz gbuf+$100,x			and data block of file.
				inx
				bne H35A0
				ldy #$0B				move user specified date/time
cmvtime			lda (A3L),y				to directory.
				sta d_filid,y
				txa		 				if all 4 bytes of date/time = 0
				ora (A3L),y				then use built-in date/time.
				tax
				dey
				cpy #$07
				bne cmvtime
				txa						does user want default time?
				bne cmvname				if not.
				ldx #$03
mvdftime 		lda p8date,x			move current default date/time
				sta d_credt,x
				dex
				bpl mvdftime
cmvname			lda (A3L),y				y = index to file kind.
				cmp #$04
				lda #$10				assume tree type
				bcc csvfkind
				lda #$D0			 	it's directory.
csvfkind 		ldx namptr			 	index to local name of pathname.
				ora pathbuf,x			combine file kind with name length.
				sta d_stor			 	sos calls this 'storage type'.
				and #$0F			 	strip back to name length
				tay		 				and use as counter for move.
				clc
				adc namptr			 	calc end of name
				tax
crname			lda pathbuf,x			move local name as filename
				sta d_stor,y
				dex
				dey
				bne crname
				ldy #$03				index to 'access' parameter
				lda (A3L),y
				sta d_attr
				iny						also move 'file identification'
				lda (A3L),y
				sta d_filid
cmvauxid 		iny						move auxillary identification bytes
				lda (A3L),y
				sta d_auxid-5,y
				cpy #$06
				bne cmvauxid
				lda xdosver				save current xdos version #
				sta d_sosver
				lda compat			 	and backward compatibility #
				sta d_comp
				lda #$01			 	usage is always 1 block
				sta d_usage
				lda d_head				place back pointer to header block
				sta d_dhdr
				lda d_head+1
				sta d_dhdr+1
				lda d_stor				storage type.
				and #$E0			 	is it a directory?
				beq cralcblk			branch if seed file.
				ldx #$1E			 	move header to data block
cmvheadr 		lda d_stor,x
				sta gbuf+4,x
				dex
				bpl cmvheadr
				eor #$30
				sta gbuf+4				make it a directory header mark.
				ldx #$07			 	overwrite password area and other
cmvpass			lda pass,x				header info.
				sta gbuf+20,x
				lda xdosver,x
				sta gbuf+32,x
				dex
				bpl cmvpass
				ldx #$02				and include info about parent directory
				stx d_eof+1
cmvparnt 		lda d_entblk,x
				sta gbuf+39,x
				dex
				bpl cmvparnt
				lda h_entln				lastly, the length of parent's
				sta gbuf+42				directory entries.
cralcblk 		jsr alc1blk				get address of file's data block
				bcs crerr3
				sta d_frst
				sty d_frst+1
				sta bloknml
				sty bloknml+1
				jsr wrtgbuf				go write data block of file
				bcs crerr3
				inc h_fcnt			 	add 1 to total # of files in this dir
				bne credone
				inc h_fcnt+1
credone			jsr drevise				go revise directories with new file
				bcs crerr3
				jmp upbmap			 	lastly, update volume bitmap
entcalc			lda /gbuf				set high address of dir entry
				sta zpt+1			  	index pointer.
				lda #$04			 	calc address of entry based
				ldx d_entnum			on the entry #.
H3689  			clc
H368A  			dex		 				addr = gbuf + ((d_entnum-1) * h_entln)
				beq H3696			  	branch with carry clear = no errors.
				adc h_entln
				bcc H368A
				inc zpt+1			  	inc hi address.
				bcs H3689				always.
H3696  			sta zpt			  		newly calculated low address.
crerr3 			rts		 				carry set if error.

drevise			lda p8date
				beq drevise1		  	if no clock, then don't mod date/time.
				ldx #$03
modtime			lda p8date,x			move last modification date/time
				sta d_moddt,x			to entry being updated.
				dex
				bpl modtime
drevise1 		lda d_attr				mark entry as backupable
				ora bkbitflg			(bit 5 = backup needed)
				sta d_attr
				lda d_dev			  	get device # of directory
				sta devnum			 	to be revised
				lda d_entblk			and address of direcotry block.
				ldx d_entblk+1
				jsr rdblk			  	read block into general purpose buffer
				bcs crerr3
				jsr entcalc				fix up ptr to entry location within gbuf.
				ldy h_entln				now move 'd.' info to directory.
				dey
H36CA  			lda d_stor,y
				sta (zpt),y
				dey
				bpl H36CA
				lda d_head				is the entry block same as
				cmp bloknml				the entry's header block?
				bne H36E0			  	if no, go save entry block
				lda d_head+1			then maybe, so test high addresses.
				cmp bloknml+1
				beq uphead			 	branch if they are the same block.
H36E0  			jsr wrtgbuf				go write updated directory block.
				bcs crerr3
				lda d_head			 	get address of header block and
				ldx d_head+1
				jsr rdblk			  	go read in header block to modify.
				bcs crerr3
uphead			ldy #$01				update current # of files in this dir.
H36F2  			lda h_fcnt,y
				sta gbuf+37,y			(current entry count)
				dey
				bpl H36F2
				lda h_attr			 	also update header's attributes.
				sta gbuf+34
				jsr wrtgbuf				go write updated header
				bcs H375A
ripple			lda gbuf+4				test for 'root' directory because
				and #$F0			 	if it is, then directory revision
				eor #$F0			 	is complete (leaves carry clear).
				beq H3770			  	branch if done.
				lda gbuf+41				get entry #
				sta d_entnum
				lda gbuf+42				and the length of ertries in that dir
				sta h_entln
				lda gbuf+39				get addr of parent entry's dir block
				ldx gbuf+40
				jsr rdblk			  	read it
				bcs H375A
				jsr entcalc				get indirect ptr to parent entry in gbuf
				lda p8date				don't touch mod
				beq H373B			  	if no clock...
				ldx #$03			 	update the modification date & time
				ldy #$24			 	for this entry too
H3732  			lda p8date,x
				sta (zpt),y
				dey
				dex
				bpl H3732
H373B  			jsr wrtgbuf				write updated entry back to disk.
				bcs H375A			  	if error.
				ldy #$25			 	compare current block # to this
				lda (zpt),y				entry's header block.
				iny
				cmp bloknml				are low addresses the same?
				sta bloknml
				bne H3751			 	branch if entry doesn't reside in same
				lda (zpt),y				block as header.
				cmp bloknml+1			are high address the same?
				beq ripple			 	they are the same, continue to root dir.
H3751  			lda (zpt),y				not same so read in this dir's header.
				sta bloknml+1
				jsr rdgbuf
				bcc ripple				continue if read was good
H375A  			rts
tsterr 			lda #$52				not tree or dir, unrecognized type
				sec
				rts
tstsos			lda gbuf			 	pointer to previous dir block
				ora gbuf+1			 	must be null
				bne tsterr
				lda gbuf+4			 	test for header
				and #$E0
				cmp #$E0
				bne tsterr
H3770  			clc		 				no error
				rts
findfile 		jsr lookfile			see if file exists
				bcs nofind
moventry 		ldy h_entln
H377A  			lda (zpt),y				move entry into storage
				sta d_stor,y
				dey
				bpl H377A
				lda #$00				no errors
nofind 			rts

lookfile 		jsr preproot			go find volume
				bcs fnderr

				bne lookfil0			branch if more than root
				lda /gbuf			 	otherwise, report a bad path error
				sta zpt+1			  	(but 1st create a phantom entry
				lda #$04			 	for open)
				sta zpt

				ldy #$1F				move in id and date info

phantm1  		lda (zpt),y
				sta d_stor,y
				dey
				cpy #$17
				bne phantm1

phantm2  		lda rootstuf-$10,y
				sta d_stor,y
				dey
				cpy #$0F
				bne phantm2
				lda #$D0				fake directory file
				sta d_stor
				lda gbuf+2			 	check forward link.
				ora gbuf+3			 	if non-zero, assume full sized directory
				bne H37C2			 	else assume it's the slot 3 /RAM volume
				lda #$02			 	so reset eof and blocks_used fields
				sta d_eof+1
				lda #$01
				sta d_usage
H37C2  			lda #MLI.E.INVPATH		bad path (carry set)
				rts
lookfil0		stz nofree				reset free entry indicator.
				sec		 				dir to be searched has header in this block.
L37C9  			stz totent			 	reset entry counter.
				jsr looknam				look for name pointed to by pnptr.
				bcc namfound			if name was found.
				lda entcntl				have we looked at all of the
				sbc totent			 	entries in this directory?
				bcc L37E2			  	maybe, check hi count.
				bne L37EB			  	no, read next directory block.
				cmp entcnth				has the last entry been looked at?
				beq errfnf			 	yes, give 'file not found' error
				bne L37EB				or branch always.
L37E2  			dec entcnth				should be at least one
				bpl L37EB			  	so this should be branch always...

errdir 			lda #MLI.E.BADDIR	 	directory error
fnderr 			sec
				rts

L37EB  			sta entcntl				keep a running count.
				lda /gbuf			 	reset indirect pointer
				sta zpt+1
				lda gbuf+2			 	get link to next dir block
				bne L37FC			  	(if there is one).
				cmp gbuf+3			 	are both zero, i.e. no link? if so,
				beq errdir			 	then not all entries were acct'd for.
L37FC  			ldx gbuf+3			 	acc has value for block# (low).
				jsr rdblk			  	go read the next linked directory.
				bcc L37C9			  	if no error.
				rts		 				return error in acc.
errfnf 			lda nofree				was any free entry found?
				bne fnf0
				lda gbuf+2			 	test link
				bne L3814
				cmp gbuf+3			 	if both are 0 then give up.
				beq fnf0			 	report 'not found'.
L3814  			sta d_entblk
				lda gbuf+3
				sta d_entblk+1			assume 1st entry of next block
				lda #$01			 	is free for use.
				sta d_entnum			mark as valid (for create)
				sta nofree
fnf0   			jsr nxtpnam1			'file not found' or 'path not found'?
errpath1 		sec		 				if non-zero then 'path not found'
				beq fnf1

				lda #MLI.E.PNOTFND		path not found
				rts

fnf1   			lda #MLI.E.FNOTFND	 	file not found
				rts

namfound 		jsr nxtpname			adj index to next name in path.
				beq filfound			branch if that was the last name.
				ldy #$00			 	be sure this is a directory entry.
				lda (zpt),y				high nibble will tell.
				and #$F0
				cmp #$D0			 	is it a subdirectory?
				bne errpath1			error if not.
				ldy #$11			 	get address of 1st subdirectory block
				lda (zpt),y
				sta bloknml				(no checking done for a valid block#)
				iny
				sta d_head			 	save as file's header block too
				lda (zpt),y
				sta bloknml+1
				sta d_head+1
				jsr rdgbuf			 	read subdirectory into gbuf.
				bcs fnderr1				if error.
				lda gbuf+37				get the # of files contained in this
				sta entcntl				directory.
				lda gbuf+38
				sta entcnth
				lda gbuf+20				make sure password is disabled
				ldx #$00
				sec
				rol
L3869  			bcc L386C
				inx
L386C  			asl
				bne L3869
				cpx #$05				is password disabled?
				beq movhead

				lda #MLI.E.INCFF	 	directory is not compatible
fnderr1  		sec
				rts
movhead  		jsr movhed0				move directory info.
				jmp lookfil0			do next local pathname.

movhed0			ldx #$0A				move this directory info
L387F  			lda gbuf+28,x
				sta h_credt,x
				dex
				bpl L387F
				lda gbuf+4				if this is root, then nothing to do
				and #$F0
				eor #$F0			 	test header type.
				beq L389C			  	branch if root
				ldx #$03			 	otherwise, save owner info about
L3893  			lda gbuf+39,x			this header.
				sta own_blk,x
				dex
				bpl L3893
L389C  			rts

filfound 		lda h_maxent			figure out which entry # this is
				sec
				sbc cntent			 	max entries - count entries + 1
				adc #$00			 	= entry # (carry was set)
				sta d_entnum
				lda bloknml				and indicate block # of this directory
				sta d_entblk
				lda bloknml+1
				sta d_entblk+1
				clc
				rts
looknam			lda h_maxent			reset count of files per block
				sta cntent
				lda /gbuf
				sta zpt+1
				lda #$04
L38C1  			sta zpt			  		reset indirect pointer to gbuf
				bcs L38F8				branch if this block contains a header
				ldy #$00
				lda (zpt),y				get length of name in directory.
				bne isname				branch if there is a name.
				lda nofree				test if a free entry has been declared.
				bne L38F8			  	yes, inc to next entry.
				jsr filfound			set address for current entry.

				inc nofree				indicate a free spot has been found.
				bne L38F8			  	always.
isname 			and #$0F			 	strip byte (is checked by 'filfound')
				inc totent				inc count of valid files found.
				sta namcnt				save name length as counter.
				ldx namptr			 	get index to current path.
				cmp pathbuf,x			are both names the same length?
				bne L38F8			  	no, inc to next entry.
cmpname  		inx		 				(first) next letter index
				iny
				lda (zpt),y				compare names letter by letter
				cmp pathbuf,x
				bne L38F8
				dec namcnt			 	all letters compared?
				bne cmpname				no, continue.
				clc		 				a match is found.
noname 			rts
L38F8  			dec cntent				checked all entries in this block?
				sec
				beq noname			 	yes, no name match.
				lda h_entln				add entry length to current pointer
				clc
				adc zpt
				bcc L38C1			  	branch if still in 1st page.
				inc zpt+1			  	look on 2nd page.
				clc		 				carry should always be clear before
				bcc L38C1			  	looking at next.

preproot 		jsr findvol				search vcb's and dev's for spec'd volume
				bcs novolume
				lda #$00				zero out directory temps
				ldy #$42
L3914  			sta own_blk,y			and owner info
				dey
				bpl L3914
				lda devnum			 	setup device # for this directory
				sta d_dev
				jsr movhed0				setup other header info from directory
				ldy #$01			 	in gbuf and clean up misc info.
				ldx vcbptr
				inx
L3929  			lda vcbbuf+18,x			misc info includes
				sta h_tblk,y			total # of blocks,
				lda vcbbuf+26,x			the address of the 1st bitmap,
				sta h_bmap,y
				lda	bloknml,y			directory's disk address,
				sta d_head,y
				lda h_fcnt,y			and setting up a counter for the # of
				sta entcntl,y			files in this directory.
				dex
				dey
				bpl L3929
nxtpname 		jsr nxtpnam1			get new namptr in y and namlen in acc.
				sty namptr			 	save new pathname pointer.
				rts		 				(status reg according to accumulator)
nxtpnam1 		ldy namptr			 	inc pathname pointer to next name
				lda pathbuf,y			in the path.
				sec
				adc namptr			 	if this addition results in zero,
				tay		 				then prefixed directory has been moved
				bne L395F			  	to another device. branch if not.
				lda devnum			 	revise devnum for prefixed directory
				sta p_dev
L395F  			lda pathbuf,y			test for end of name.
				clc						no errors
novolume 		rts

findvol	 		lda #$00
				ldy preflag				use prefix volume name to look up vcb.
				bit prfxflg				is this a prefixed path?
				bpl L396F			 	branch if it is
				tay		 				set ptr to volume name
L396F  			sty vnptr			  	and save.
				sta devnum			 	zero out dev# until vcb located.
L3975 			pha		 				acc now used as vcb lookup index.
				tax		 				index pointer to x.
				lda vcbbuf,x			get vcb volume name length.
				bne L3987			  	branch if claimed vcb to be tested.
L397C 			ldy vnptr			  	restore pointer to requested vol name.
				pla		 				now adj vcb index to next vcb entry.
				clc
				adc #$20
				bcc L3975			  	branch if more vcb's to check
				bcs L39D4			  	otherwise go look for unlogged volumes.
L3987  			sta namcnt			 	save length of vol name to be compared.
L398A  			cmp pathbuf,y			is it the same as requested vol name?
				bne L397C			  	branch if not
				inx
				iny		 				next character
				lda vcbbuf,x
				dec namcnt			 	last character?
				bpl L398A			  	if not.
				plx		 				restore pointer to matching vcb.
				stx vcbptr			 	save it for future reference.
				lda vcbbuf+16,x			get it's device #
				sta devnum			 	and save it.
				stz bloknml+1			assume prefix is not used and
				lda #$02			 	that root directory is to be used.
				sta bloknml
				lda vnptr			  	= 0 if no prefix.
L39AC  			tay		 				if prefix then find ptr to prefixed
				sta namptr			 	dir name. save path ptr.
				beq L39C2			  	branch if no prefix.
				sec
				adc pathbuf,y			inc to next dir in prefix path.
				bcc L39AC			  	branch if another dir in prefix.
				lda p_blok			 	volume verification will occur at
				sta bloknml				subdirectory level.
				lda p_blok+1
				sta bloknml+1

* verify volume name

L39C2  			jsr rdgbuf				read in directory (or prefix dir)
				bcs L39CC			  	if error then look on other devices.
				jsr cmppnam				compare dir name with path name.
				bcc L39F0			  	if they match, stop looking.
L39CC  			ldx vcbptr			 	check if current (matched) vcb is active
				lda vcbbuf+17,x			i.e. does it have open files?
				bmi L39ED			  	report not found if active.
L39D4  			lda vnptr			  	make path ptr same as volume ptr
				sta namptr
				jsr mvdevnums			copy all device #'s to be examined.
				lda devnum			 	log current device 1st before searching
				bne L39F1			  	others.
L39E2  			ldx numdevs				scan look list for devices we need
L39E5  			lda loklst,x			to search for the requested volume.
				bne L39F4			  	branch if we've a device to look at.
				dex
				bpl L39E5			  	look at next one.
L39ED  			lda #MLI.E.VNOTFND	 	no mounted volume
				sec						error
L39F0  			rts

L39F1  			ldx numdevs				now remove the device from the list
L39F4  			cmp loklst,x			of prospective devices.
				beq L39FE			  	branch if match.
				dex		 				look until found.
				bpl L39F4			  	always taken (usually) unless
				bmi L39ED			  	if dev was removed from devlst (/RAM).
L39FE  			sta devnum			 	preserve device to be checked next.
				stz loklst,x			mark this one as tested.
				jsr fnddvcb				find vcb that claims this dev (if any).
				bcs L3A29			  	branch if vcb full.
				ldx vcbptr			 	did fndvcb find it or return free vcb?
				lda vcbbuf,x
				beq L3A16				if free vcb.
				lda vcbbuf+17,x			is this volume active?
				bmi L39E2			  	if so, no need to re-log.
L3A16  			lda #$02			 	go read root dir into gbuf
				ldx #$00
				jsr rdblk
				bcs L39E2			  	ignore if unable to read.
				jsr logvcb				go log in volume name.
				bcs L39E2			  	look at next if non-xdos disk mounted.
				jsr cmppnam				is this the volume ?
				bcs L39E2			  	if not
L3A29  			rts
mvdevnums 		ldx numdevs				copy all dev #'s to be checked.
L3A2D  			lda devlist,x		   	active device list.
				and #$F0			 	strip device type info.
				sta loklst,x			copy them to a temp workspace
				dex
				bpl L3A2D
				ldx numdevs
				rts
fnddvcb			lda #$00				look for vcb with this device#
				ldy #$FF
L3A40  			tax						new index to next vcb
				lda vcbbuf+16,x			check all devnums
				cmp devnum				is this the vcb?
				bne L3A4E			  	if not
				stx vcbptr
				clc		 				indicates found
				rts
L3A4E  			lda vcbbuf,x			is this a free vcb?
				bne L3A57				if not
				iny
				stx vcbptr
L3A57  			txa
				clc						inc index to next vcb
				adc #$20
				bne L3A40
				tya		 				any free vcb's available?
				bpl L3A79			  	yes
				lda #$00			 	look for an entry to kick out
L3A62  			tax
				lda vcbbuf+17,x			any open files?
				bpl L3A70			  	no, kick this one out.
				txa		 				next vcb
				clc
				adc #$20			 	(vcb entry size)
				bne L3A62
				beq L3A7A			  	all vcb entries have open files
L3A70  			stx vcbptr			 	save entry index.
				stz vcbbuf,x			free this entry
				stz vcbbuf+16,x
L3A79  			clc		 				no error.
L3A7A  			lda #$55			 	# vcb full error
				rts
cmppnam			ldx #$00			 	index to directory name.
				ldy namptr			 	index to pathname.
				lda gbuf+4			 	get dir name length and type.
				cmp #$E0				is it a directory?
				bcc L3A90			  	if not.
				and #$0F			 	isolate name length and
				sta namcnt			 	save as a counter.
				bne L3A95			  	branch if valid length.
L3A90  			sec		 				indicate not found
				rts

L3A92  			lda gbuf+4,x			next char
L3A95  			cmp pathbuf,y
				bne L3A90			  	if not the same.
				inx		 				check next char
				iny
				dec namcnt
				bpl L3A92			  	if more to compare.

				clc		 				match found
				rts

logvcb			ldx vcbptr			 	previously logged in volume?
				lda vcbbuf,x			(acc = 0?)
				beq logvcb1			  	no, go prepare vcb.
				jsr cmpvcb			 	does vcb match vol read?
				bcc L3B05			  	yes, do not disturb.
logvcb1			ldy #$1F			 	zero out vcb entry

L3AB2  			stz vcbbuf,x
				inx
				dey
				bpl L3AB2
	
				jsr tstsos				make sure it's an xdos disk
				bcs L3B05				if not, return carry set.

				jsr tstdupvol			does a duplicate with open files
				bcs L3B04			 	already exist? branch if yes.

				lda gbuf+4			 	move volume name to vcb.
				and #$0F			 	strip root marker
				tay
				pha
				ora vcbptr
				tax
L3ACE  			lda gbuf+4,y
				sta vcbbuf,x
				dex
				dey
				bne L3ACE
				pla		 				get length again
				sta vcbbuf,x			and save.
				lda devnum			 	last device used.
				sta vcbbuf+16,x			save device # and
				lda gbuf+41				total # of blocks on this unit.
				sta vcbbuf+18,x
				lda gbuf+42
				sta vcbbuf+19,x
				lda bloknml				save address of root directory.
				sta vcbbuf+22,x
				lda bloknml+1
				sta vcbbuf+23,x
				lda gbuf+39				save address of the 1st bitmap.
				sta vcbbuf+26,x
				lda gbuf+40
				sta vcbbuf+27,x
L3B04  			clc		 				indicate logged if possible
L3B05  			rts

cmpvcb			lda gbuf+4			 	with name in directory.
				and #$0F
				cmp vcbbuf,x			are they the same length?
				stx xvcbptr				(see rev note #23)
				bne L3B1E			  	if not the same.
				tay
				ora xvcbptr
				tax
L3B18  			lda gbuf+4,y
				cmp vcbbuf,x
L3B1E  			sec		 				anticipate different names.
				bne L3B26			  	if not the same.
				dex
				dey
				bne L3B18
				clc		 				indicate match.
L3B26  			ldx xvcbptr				offset to start of vcb (rev note #23)
				rts
tstdupvol 		lda #$00			 	check for other logged in volumes with the same name.
L3B2C  			tax
				jsr cmpvcb
				bcs L3B41			  	if no match.
				lda vcbbuf+17,x			test for any open files.
				bmi L3B4B			  	cannot look at this volume.
				lda #$00			 	take duplicate offline if no open files
				sta vcbbuf,x
				sta vcbbuf+16,x
				beq L3B49			  	ok to log in new volume.
L3B41  			txa		 				index to next vcb
				clc
				and #$E0				strip odd stuff.
				adc #$20			 	inc to next entry.
				bcc L3B2C			  	branch if more to check
L3B49  			clc
				rts
L3B4B  			sta duplflag			duplicate has been found.
				stx vcbentry			save pointer to conflicting vcb.
				sec		 				error.
				rts

tstfrblk 		ldx vcbptr			 	test if enough free blocks available for request.
				lda vcbbuf+21,x			check if proper count for this volume.
				ora vcbbuf+20,x
				bne L3BAD			  	branch if count is non-zero.

tkfrecnt 		jsr cntbms				get # of bitmaps
				sta bmcnt			  	and save.
				stz scrtch			 	start count at 0
				stz scrtch+1
				lda #$FF			 	mark 'first free' temp as unknown
				sta nofree
				jsr upbmap			 	update volume bitmap.
				bcs L3BC1			  	if error.
				ldx vcbptr			 	get address of 1st bitmap
				lda vcbbuf+26,x
				sta bloknml
				lda vcbbuf+27,x
				sta bloknml+1
L3B81  			jsr rdgbuf			 	use general buffer for temp space to
				bcs L3BC1			  	count free blocks (bits).
				jsr count
				dec bmcnt			  	was that the last bitmap?
				bmi L3B96			  	if so, go change fcb so not done again.
				inc bloknml
				bne L3B81
				inc bloknml+1
				bra L3B81
L3B96  			ldx vcbptr			 	mark which block had 1st free space
				lda nofree
				bmi L3BBE			 	if no free space was found.
				sta vcbbuf+28,x			update the free count.
				lda scrtch+1
				sta vcbbuf+21,x			update volume control byte.
				lda scrtch
				sta vcbbuf+20,x
L3BAD  			lda vcbbuf+20,x			compare total available free blocks
				sec		 				on this volume.
				sbc reql
				lda vcbbuf+21,x
				sbc reqh
				bcc L3BBE
				clc
				rts

L3BBE  			lda #MLI.E.VOLFULL
				sec
L3BC1  			rts

count			ldy #$00

L3BC4  			lda gbuf,y				bit pattern.
				beq L3BCC			  	don't count
				jsr cntfree
L3BCC  			lda gbuf+$100,y			do both pages with same loop
				beq L3BD4
				jsr cntfree
L3BD4  			iny
				bne L3BC4			  	loop until all 512 bytes counted.
				bit nofree			 	has 1st block w/free space been found?
				bpl L3BEE			  	if yes.
				lda scrtch			 	test to see if any blocks were counted
				ora scrtch+1
				beq L3BEE			  	branch if none counted.
				jsr cntbms			 	get total # of maps.
				sec		 				subtract countdown from total bitmaps
				sbc bmcnt
				sta nofree
L3BEE  			rts

cntfree			asl			  			count the # of bits in this byte
				bcc L3BFA
				inc scrtch
				bne L3BFA
				inc scrtch+1
L3BFA  			ora #$00
				bne cntfree				loop until all bits counted
				rts
cntbms			ldx vcbptr
				ldy vcbbuf+19,x			return the # of bitmaps
				lda vcbbuf+18,x			possible with the total count
				bne L3C0B			  	found in the vcb.
				dey						adj for bitmap block boundary
L3C0B  			tya
				lsr			  			divide by 16. the result is
				lsr			  			the # of bitmaps.
				lsr
				lsr
				rts
MAN
SAVE USR/SRC/PRODOS.FX/PRODOS.S.XDOS.B
LOAD USR/SRC/PRODOS.FX/PRODOS.S
ASM