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)