R0l0Player 3 File System Specification

1. general info
(all numbers decimal)

structure:
- reserved area (16 sectors)
- vtoc
- data

cluster size: 256 sectors (128kB)
max. file size: 32768 clusters (4194304kB)
max. part. size: 1048576 clusters (128GB)


2. formatting partition - calculating values:
(all numbers decimal)

x - total sectors (x>=2066)
n - total clusters
v - first sector of data
z - first sector after data

n=int((x-17)/256.001954)
v=int((n+511)/512)+16
z=v+256*n

vtoc starts at sector #16


3. boot record (sector #0)
(all numbers hexadecimal)

offset    len    content
-------------------------------------------------------
000    001    file system ID ('R'*)
001    003    reserved (00)
004    001    file system version (10)
005    001    reserved (00)
006    008    file system name ('RPlay3FS')
00E    001    volume status
        b7:    U unclosed filesystem
        b6:    B bad sector(s) detected
        b5-0:      reserved (00)
00F    001    extended status
        b7:    L volume uses lba mode
010    003    volume format date (m,d,y)
013    003    volume format time (h,m,s)
016    002    serial number
018    002    sequential number
01A    002    number of cylinders
01C    001    number of heads
01D    001    number of sectors per track
01E    002    reserved (00)
020    020    volume label (ASCII, padded with spaces)

040    004    volume size in sectors
044    004    total number of clusters
048    004    number of free clusters
04C    004    number of first free cluster

050    004    first vtoc sector # (lba absolute)
054    004    first data sector # (lba absolute)

058    008    reserved (00)

root directory parameters:
060    004    physical address of map cluster
064    004    map cluster #
068    004    # of clusters
06C    002    # of sectors in last cluster

06E    192    reserved (00)


4. vtoc (cluster usage map) - byte oriented
(all numbers hexadecimal)

00:    empty (unused)
40:    not existing
80:    used
c0:    bad


5. sector map of file/directory
(all numbers hexadecimal)

4-byte records contains physical addresses of file clusters on disk,
table padded with 0s. If status bit L is set, they are stored in LBA format,
otherwise - each record is as follows:
000    001    sector number (byte for D113)
001    002    cylinder number (word for D114)
003    001    head/disk (byte for D116)


6. directory format
(all numbers hexadecimal)

each entry occupies one $200-byte sector and consists of following fields:
000    100    file name (currently ATASCII, planned: UTF-8), padded with 0s
100    008    8.3 file name
108    003    8.3 file extension
10B    001    file attributes:
        b7:    D - directory
        b6:    R - read only
        b5:    E - erased
        b3-0:    reserved (0)
10C    004    reserved (0)
110    003    last modification date (m, d, y)
113    003    last modification time (h, m, s)
116    01A    reserved (0)
130    004    physical address of map cluster
134    004    map cluster #
138    004    # of clusters
13C    002    # of sectors in last cluster
13E    0C2    reserved (0)

; xms manager v1.1 (neo v>=1.4) ---------------------------------------------

; globals

availableBanks  equ     $0400   1
bankCodeTable   equ     $0401   64
; bank usage Table: a=...
; 7e    - bank used by plug-in code
; 7f    - unavailable bank
; ff    - unused bank
bankUsageTable  equ     $0441   64
unusedBanks     equ     $0481   1

; local variables
temp    equ     $fe

; extended memory initialization
initializeMemory
        mva     availableBanks  unusedBanks
        ldx     #0
        lda     #$ff
initializeMemory_unused
        sta     bankUsageTable,x+
        cpx     availableBanks
        bne     initializeMemory_unused
        lda     #$7f
initializeMemory_unavailable
        cpx     #$40
        beq     initializeMemory_ret
        sta     bankUsageTable,x+
        bne     initializeMemory_unavailable    !
initializeMemory_ret
        rts
        
; extended memory banks allocation
; parameters:   X: number of needed banks
;               A: code to store in usage table
; returns:      C - set if out of memory
;               A: code of first found bank
;               Y: index of first found bank
allocateXmsBanks
        dex:cpx unusedBanks
        scc:rts
        sta     temporaryUsageCode
        ldy:dey availableBanks
allocateXmsBanks_seekLoop
        lda     bankUsageTable,y
        bmi     allocateXmsBanks_found
allocateXmsBanks_next
        dey:bpl allocateXmsBanks_seekLoop       !
allocateXmsBanks_found
        mva     temporaryUsageCode      bankUsageTable,y
        dec     unusedBanks
        dex:bpl allocateXmsBanks_next
        lda     bankCodeTable,y
        rts

; extended memory banks deallocation
; parameters:   A - usage code of deallocating banks
deallocateXmsBanks
        ldx     #0
        tay
deallocateXmsBanks_seekLoop
        cmp     bankUsageTable,x
        beq     deallocateXmsBanks_found
deallocateXmsBanks_next
        inx:cpx availableBanks
        bne     deallocateXmsBanks_seekLoop
deallocateXmsBanks_ret
        rts
deallocateXmsBanks_found
        mva     #$ff    bankUsageTable,x
        inc     unusedBanks
        tya
        jmp     deallocateXmsBanks_next