Код:
The CP/M 2.2 directory has only one type of entry:
UU F1 F2 F3 F4 F5 F6 F7 F8 T1 T2 T3 EX S1 S2 RC .FILENAMETYP....
AL AL AL AL AL AL AL AL AL AL AL AL AL AL AL AL ................
UU = User number. 0-15 (on some systems, 0-31). The user number allows multiple
files of the same name to coexist on the disc.
User number = 0E5h => File deleted
Fn - filename
Tn - filetype. The characters used for these are 7-bit ASCII.
The top bit of T1 (often referred to as T1') is set if the file is
read-only.
T2' is set if the file is a system file (this corresponds to "hidden" on
other systems).
EX = Extent counter, low byte - takes values from 0-31
S2 = Extent counter, high byte.
An extent is the portion of a file controlled by one directory entry.
If a file takes up more blocks than can be listed in one directory entry,
it is given multiple entries, distinguished by their EX and S2 bytes. The
formula is: Entry number = ((32*S2)+EX) / (exm+1) where exm is the
extent mask value from the Disc Parameter Block.
S1 - reserved, set to 0.
RC - Number of records (1 record=128 bytes) used in this extent, low byte.
The total number of records used in this extent is
(EX & exm) * 128 + RC
If RC is 80h, this extent is full and there may be another one on the disc.
File lengths are only saved to the nearest 128 bytes.
AL - Allocation. Each AL is the number of a block on the disc. If an AL
number is zero, that section of the file has no storage allocated to it
(ie it does not exist). For example, a 3k file might have allocation
5,6,8,0,0.... - the first 1k is in block 5, the second in block 6, the
third in block 8.
AL numbers can either be 8-bit (if there are fewer than 256 blocks on the
disc) or 16-bit (stored low byte first).
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