;
	; This file contains the implementation of get_dir_entry.
	; It also contains other functions for finding an entry within 
	; a directory.
	;

	string asis

	include 'gsos.equ'
	include 'minix.equ'
	include 'fst.equ'

	include 'fst.macros'

	include 'M16.Debug'

	include 'records.equ'
	include 'p.equ'





	;
	; dirent_entry 0 is a special case.
	; (assuming base = 1, displacement = 1)
	; first call:
	; before
	;   dirent_entry = 0, dirent_zone = 0, dirent_offset = 0
	; after:
	;   dirent_entry = 1, dirent_zone = 0, dirent_offset = 0
	;
	; subsequent calls:
	; before
	;   dirent_entry = 1, dirent_zone = ..., dirent_offset = ...
	; after
	;   dirent_entry = 2, dirent_zone = ..., dirent_offset = ...
	;

	; don't think this needs to be dp... move to a normal record.


data	record	


	; size of the directory, divided by dirent_size.
size		ds.l 1

displacement	ds.w 1

dirent_size	ds.w 1
dirent_zone	ds.w 1
dirent_offset	ds.w 1
dirent_entry	ds.w 1

dirent	ds v1L_dirent

	endr


	import init_fcr
	import init_vcr
	import load_inode
	import read_data_block

	import do_ignore
	import do_eof
	import do_blocks
	import do_r_eof
	import do_r_blocks
	import do_access
	import do_file_sys_id
	import do_option_list
	import do_create_date_time
	import do_mod_date_time
	import do_file_type
	import do_aux_type

	entry init
	entry base_displace
	entry find_next_dirent
	entry find_absolute_dirent
	entry find_dirent_block
	entry count_entries
	entry count_dirent_block

	entry do_flags
	entry do_name_buffer_0
	entry do_name_buffer_1
	entry do_entry_num

	entry sparse_dirent_block

get_dir_entry	procname	export

	with fst_parms
	with dp
	with data

	;~DebugSetTrace #1

	jsr init_fcr
	jsr init_vcr

	; check for read-access
	ldy #fcr.access
	lda [<my_fcr],y

	and #read_access
	bne access_ok

	lda #invalid_access
	sec
	rtl

access_ok
	; is it a dir?
	ldy #fcr.disk_inode.mode
	lda [my_fcr],y
	and #S_IFMT
	cmp #S_IFDIR
	beq dir

	lda #bad_store_type
	sec
	rtl

dir

	jsr init
	jsr base_displace
	bcc @ok
	rtl

@ok

	; if data.dirent.inode is valid, load the inode
	; (if not valid, this was a base/displace of 0 to return
	; the dirent count.  field info will be returned from the 
	; directory inode)


	lda data.dirent.inode
	beq dispatch

	; if inode == the directory inode (.) , no need to re-load it.
	cmp inode
	beq dispatch

	sta inode
	jsr load_inode
	bcc dispatch
exit
	rtl

dispatch

	lda <call_class
	beq class0

class1
	lda [param_blk_ptr] ; pcount
	dec a
	asl a ; x 2
	asl a ; x 4
	tax
	dispatch get_dir_entry_dcb_1


	~DebugHexDump param_blk_ptr, #DirEntryRecGS.__sizeof

	lda tool_error
	cmp #0
	rtl

class0
	ldx #get_dir_entry_dcb_0_size-4
	dispatch get_dir_entry_dcb_0
	lda tool_error
	cmp #0
	rtl


get_dir_entry_dcb_0
	dc.w $00, do_ignore ; refnum
	dc.w $02, do_flags
	dc.w $04, do_ignore	; base
	dc.w $06, do_ignore	; displacement
	dc.w $08, do_name_buffer_0	;
	dc.w $0c, do_entry_num
	dc.w $0e, do_file_type
	dc.w $10, do_eof
	dc.w $14, do_blocks
	dc.w $18, do_create_date_time
	dc.w $20, do_mod_date_time
	dc.w $28, do_access
	dc.w $2a, do_aux_type
	dc.w $2e, do_file_sys_id

get_dir_entry_dcb_0_size equ *-get_dir_entry_dcb_0

get_dir_entry_dcb_1
	;dc.w $00, do_ignore	; pCount
	dc.w $02, do_ignore ; refnum
	dc.w $04, do_flags
	dc.w $06, do_ignore	; base
	dc.w $08, do_ignore	; displacement
	dc.w $0a, do_name_buffer_1	;
	dc.w $0e, do_entry_num
	dc.w $10, do_file_type
	dc.w $12, do_eof
	dc.w $16, do_blocks
	dc.w $1a, do_create_date_time
	dc.w $22, do_mod_date_time
	dc.w $2a, do_access
	dc.w $2c, do_aux_type
	dc.w $30, do_file_sys_id
	dc.w $32, do_option_list
	dc.w $36, do_r_eof
	dc.w $3a, do_r_blocks



	endp


init	proc

	with fst_parms,dp,data

	lda device
	sta dev_parms.dev_num

	; directory entry (and inode lookup) should be cached.
	lda #in_cache
	sta dev_parms.dev_cache_pr

	lda #1024
	sta dev_parms.dev_blk_size
	sta dev_parms.dev_req_cnt


	;stz dirent_offset
	;stz dirent_entry
	;stz dirent_zone


	ldy #fcr.dirent_zone
	lda [my_fcr],y
	sta dirent_zone

	ldy #fcr.dirent_offset
	lda [my_fcr],y
	sta dirent_offset

	ldy #fcr.dirent_entry
	lda [my_fcr],y
	sta dirent_entry


	stz data.dirent.inode
	stz data.dirent.name

	lda #v1_dirent.__sizeof
	sta dirent_size


	lda disk_inode.size
	sta size
	lda disk_inode.size+2
	sta size+2

	; / 2
	lsr size+2
	ror size

	; / 4
	lsr size+2
	ror size

	; / 8
	lsr size+2
	ror size

	;  / 16
	lsr size+2
	ror size


	~DebugHexDump <my_vcr, #vcr.__sizeof

	ldy #vcr.super.magic
	lda [my_vcr],y

	cmp #v1L.MAGIC
	bne minix
	; this is 
linux
	; linux dirents are twice as big.

	asl dirent_size

	;  / 32
	lsr size+2
	ror size


minix
	rts

	endp


base_displace	proc

	with fst_parms, dp
	with data

	; offset is $04 for class 0, $06 for class 1
	lda #$04
	clc
	adc <call_class
	tay

	lda [param_blk_ptr],y ; base
	cmp #3
	bcs perr

	asl a
	tax

	iny
	iny
	lda [param_blk_ptr],y ; displacement
	sta displacement

	jmp (base_table,x)


perr
	lda #parm_range_err
	sec
	rts

base_table
	dc.w absolute, forward, backward

absolute
	; absolute with a displacement of 0 -> return total count.
	;
	cmp #0
	beq @count
	jmp find_absolute_dirent
@count
	jmp count_entries

forward
	jmp find_next_dirent
	;
backward
	; backward 0 ? == forward 0
	cmp #0
	beq forward

	eor #$ffff
	sec ; inc / clc
	adc dirent_entry
	sta displacement

	jmp find_absolute_dirent

	endp



count_entries proc
	; count the number of entries.

	with fst_parms
	with dp, data

	; read each block and count the entries.
	; only handles direct blocks. so there.


	; disk inode has been copied to the dp.
	stz dirent_entry
	ldx #0
zone_loop
	stx dirent_zone
	lda disk_inode.zone,x
	bne @ok ; directory should not be sparse!
	; sparse!
	jsr sparse_dirent_block
	bcs done
	bra next

@ok
	jsr read_data_block
	bcs exit

;	~DebugHexDump <io_buffer, #1024

	jsr count_dirent_block
	lda size
	beq done

next
	ldx dirent_zone
	inx
	inx
	cpx #v1.NR_DZONES*2
	bcs done
	bra zone_loop
	; 
	; minix has 16-byte dirents.
	; linux has 32-byte dirents.


done

	; also reset the displacement to 0.
	lda #0
	ldy #fcr.dirent_entry
	sta [my_fcr],y
	ldy #fcr.dirent_zone
	sta [my_fcr],y
	ldy #fcr.dirent_offset
	sta [my_fcr],y

	clc
exit
	rts
	endp

count_dirent_block proc

	; 16-byte dirent entries -- 64 per block.
	with dp, data

	ldy #0
loop
	lda [io_buffer],y
	beq next
	inc dirent_entry
next
	; not 32-bit safe.
	dec size
	beq done

	tya
	clc
	adc dirent_size
	tay
	cmp #1024
	bcc loop

done
	rts

	endp



strlen	proc
	; strlen the dirent.
	; will be 0-terminated unless if < dirent size.

	lda data.dirent.inode
	beq exit

	ldx #2
	short m
loop
	lda data.dirent,x
	beq zero
	inx
	cpx data.dirent_size
	bcc loop
zero  
	long m

	txa
	dec a ; -2 for dirent.inode
	dec a

exit
	rts
	endp

do_flags	proc
	with fst_parms

	; $8000 for extended file, 0 for everything else.
	lda #0
	sta [param_blk_ptr],y
	rts
	endp

do_entry_num	proc
	with fst_parms
	with data

	lda dirent_entry
	sta [param_blk_ptr],y
	rts
	endp

do_name_buffer_0 proc
	with fst_parms
	with dp

	lda [param_blk_ptr],y
	sta ptr
	iny
	iny
	lda [param_blk_ptr],y
	sta ptr+2

	ora ptr
	beq exit


copy_it

	phx
	jsr strlen
	; strlen handles inode = 0

	tax
	tay 

	short m

	sta [ptr]

	; no need to dey since there is a length byte.
	dex
	bmi @done

@loop
	lda data.dirent.name,x
	sta [ptr],y
	dey
	dex
	bpl @loop
@done
	long m
	plx
exit
	rts
	endp

do_name_buffer_1 proc
	with fst_parms
	with dp

	lda [param_blk_ptr],y
	sta ptr
	iny
	iny
	lda [param_blk_ptr],y
	sta ptr+2

	ora ptr
	beq exit

	phx
	jsr strlen

	pha ; save
	lda [ptr] ; total output buffer size
	sec
	sbc #4
	bmi error
	cmp 1,s
	bcs ok


error_store_size
	ldy #2
	sta [ptr],y

error
	pla
	lda #buff_too_small
	sta tool_error
	plx
	rts

ok
	pla ; strlen
	ldy #2
	sta [ptr],y

	tax
	tay
	iny ; skip gs/os string overhead
	iny
	iny
	short m
	dex
	bmi @done
@loop
	lda data.dirent.name,x
	sta [ptr],y
	dey
	dex
	bpl @loop
@done
	long m
	plx

exit
	rts
	endp


;
;
; new code....
; here's our big insight
; 1. base 1, displacement xxx is equivalent to stepping forward xxx entries. 
; 2. base 2, displacement xxx is equivalent to base 0, displacement fcr.dirent_entry - displacement
; 2a. if displacement is 0, is equivalent to stepping forward 0 entries.
; 3. base 0, displacement xxx is equivalent to base 1 displacement xxx when fcr.dirent_entry = 0
;
; therefore the only special case is dirent_entry == 0 (since displacement 1 -> read entry 0)
;
;
find_absolute_dirent proc
	with data

	; if displacement > dirent_entry, we can re-use that info.
	lda displacement
	cmp dirent_entry
	bcc no

	sec
	sbc dirent_entry
	sta displacement
	bra find_next_dirent

no
	stz dirent_entry
	stz dirent_zone
	stz dirent_offset

	bra find_next_dirent
	endp

find_next_dirent proc
	with data, dp

	lda dirent_entry
	beq @first
	dec dirent_entry
	bra @ok
@first
	dec displacement
	bmi eod
@ok

	; make sure dir not empty (should never happen...)
	lda size
	beq eod

	ldx dirent_zone

loop
	lda disk_inode.zone,x
	beq sparse ; should never happen...
	phx ; save
	jsr read_data_block
	plx
	bcs exit

;	phx
;	phy
;	pha
;	~DebugHexDump <io_buffer, #1024
;	pla
;	ply
;	plx



	jsr find_dirent_block
	bcc next
	; a = 0 if it was found!
	cmp #1
	rts

next
	inx
	inx
	stz dirent_offset

	cpx #v1.NR_DZONES*2
	bcs exit
	bra loop

sparse
	jsr sparse_dirent_block
	bcs eod
	bra next


found_it
	;stx dirent_zone
	;sty dirent_offset
	clc
exit
	rts

eod
	lda #end_of_dir
	sec
	rts
	endp

	;
	; returns:
	; carry set on error or if found.
	; a = 0 if found, or error.
	;
	; inputs y = dirent offset
find_dirent_block	proc
	with dp, data

	ldy dirent_offset
loop
	lda [io_buffer],y
	beq next

	inc dirent_entry
	dec displacement
	bmi found_it

next
	dec size
	beq eod

	tya
	clc
	adc dirent_size
	tay
	cmp #1024
	bcc loop
	; not found ...

	lda #0
	clc
	rts

eod
	lda #end_of_dir
	sec
	rts


found_it
	; we found our entry!!!
	; copy it over.

	stx dirent_zone
	sty dirent_offset
	; dirent_entry updated above.

	ldx #0
@loop
	lda [io_buffer],y
	sta data.dirent,x
	iny
	iny
	inx
	inx
	cpx dirent_size
	bcc @loop


	; update the fcr.

	lda dirent_entry
	ldy #fcr.dirent_entry
	sta [my_fcr],y

	lda dirent_offset
	ldy #fcr.dirent_offset
	sta [my_fcr],y

	lda dirent_zone
	ldy #fcr.dirent_zone
	sta [my_fcr],y

	lda #0
	sec ; found!
	rts

	endp


strcmp	proc
	; clobbers ptr

	; check if the name is even possible...

	with dp

	import target:GSString32

	ldx target.length
	beq no

	; dirent size is DIRSIZE + 2. -1 
	; to compare >= DIRSIZE+1
	lda data.dirent_size
	dec a
	cmp target.length
	bcs no	

	iny ; skip inode
	iny 
	tya
	clc
	adc io_buffer
	sta ptr
	adc io_buffer+2
	sta ptr+2

	ldx target.length
	beq no
	ldy #0
	short m

	; y = offset
	; x = length of target string.
loop
	lda [ptr],y
	beq eos
	cmp target.text,y
	bne no8
	iny 
	dex
	bne loop
	long m
yes
	clc
	rts

eos
	long m
	; end of string. if x = 1, it's a match!
	dex
	beq yes


no8
	long m
no
	sec
	rts

	endp

sparse_dirent_block	proc
	; (not 32-bit safe)

	; decrease size by the appropriate amount
	; for a sparse block.
	; (should probably never happen!)

	; sets c if size <= 0

	with data

	lda dirent_size
	cmp #32 ; linux? 32 dirents per block
	beq @ok
	lda #64 ; minix? 64 dirents per block
@ok
	eor #$ffff
	sec
	adc size
	sta size
	bmi eod
	beq eod
	clc
	rts
eod
	sec
	rts

	endp

find_entry_by_name proc export

	; scan the directory and search by name...

	with dp
	with data

	jsr init
	lda size
	beq fnf
	bmi fnf

	ldx #0
block_loop
	; x = dirent_zone
	stx dirent_zone
	lda disk_inode,x
	beq sparse

	jsr read_data_block
	bcc @ok
	rts

@ok
	ldy #0

dirent_loop
	; y = dirent offset
	sty dirent_offset

	lda [io_buffer],y
	beq next_dirent
	sta inode ; optomistic...

	jsr strcmp
	bcs next_dirent

	; found it!
	lda #0
	clc
	rts

next_dirent

	dec size
	beq fnf

	lda dirent_offset
	clc
	adc dirent_size
	tay 
	cmp #1024
	bcs next_zone
	bra dirent_loop


next_zone
	ldx dirent_zone
	inx
	inx
	cpx #v1.NR_DZONES*2
	bcc block_loop
	; all out of zones -> not found!


fnf
	stz inode
	lda #file_not_found
	sec
	rts

sparse
	; sparse block. jump to the next zone, decrement size appropriately.
	jsr sparse_dirent_block
	bcs fnf
	bra next_zone

	endp


	end