Inferno #04 22 июня 2003

Программирование

Softinka - MEMDISK - file system for storing files in memory.

  MEMDISK - file system for memory

MEMDISK designed for storing files
memory areas. Memory may be fragmented, so a few chip I2C
EEPROM can be used as a
disc. It is also useful for ramdiskov in
page-RAM or files stored in
EPROM.

The structure of the MEM / 0 was first ideey.V revised version 
of MEM / 1 were added pointers to roditelya.Tak that now only 
one pointer to operate the file or directory, and there is no 
need to memorization of pointers to elements of the path.


This makes it easier, for example, deleting files or
moving to another directory.


            Disc structure


  content length description
+0 "MEM", # 1 April the name of the file system
4 3 characters + # 0 4 a name of a physical disk
+8 Structure F Є26 file descriptor
... structure D Є26 directory handle
... structure A Є7 descriptor area

                    Data

The first file descriptor (structure F) is always present. 
Specifies the first file or directory on disk, contains a 
useful amount of free space and a pointer to a chain of free 
area (Structures A). May also indicate

parent directory - a value of 0 means that it is the root.
Thus, the blank disc contains an 8-byte header, a structure F 
and at least one structure A. 


               Structure

Structure F - file descriptor
Structure D - directory descriptor
Structure A - data area

length of the contents of a note to:
 B str.F str.D str.A
0 4 index of this file only A

     to the next or directory

     structure of this directory
4 2 length of 20 to 64 from 1 to

     structure 65535
6 a version number # 00 # 80
7 1 Flag
8 4 a pointer to the directory containing
     parent zhaschy this domain
     structure of the file / directory st
12 April that the length

                   file data 16 4 only A pointer to the first 
GOVERNMENTAL 

     generates an element

     structure subdir.
20 4 Date and time of packed
24 Є2 name with the name name

     # 00 at the end of the catalog file

All pointers and field lengths are in the format
little Endian (least significant byte first)


        Example - a blank disc 8kB

Selected for the sample unit is
M24C64 - I2C 8kB EEPROM, connected to
AY-3-8912.

Base Pointer # E0A0, which means: memory
connected to AY (# E0 - bit 0 Port A is
SDA, bit 1 is the SCL.), And extension -
# A0. Connection number # E2 is used to
computers TC2068 means: bit 4-port
A is the SDA, bit 5 is SCL. Internal number
IC M24C64 may be in the range # A0 .. # AE (only even values) 
and set using the inputs E0, E1 and E2 chip.


address the content description
# 0000 4D 45 4D 01 file system name

                     "MEM / 1"
# 0004 45 45 30 00 physical disk name

                     "EE0" (with zero

                     code at the end)
# 0008 F 00 00 00 00 no next element
                     ment directory (here

                     begins

                     structure F)
# 000C 19 00 length of the element

                     (# 0027 - # 000E)
# 000E / 00 00 element with no established
                     lennyh flags
# 0010 00 00 00 00 No parent

                     structure
# 0014 D3 1F 00 00 full length free
                     Nogo place
# 0018 27 00 A0 E0 pointer

                     A structure, which

                     begins with # 0027
# 001C B5 44 22 2C date and time

                     Format:

                     2002-01-02 08:37:42
# 0020 45 45 44 48 53 00 4B

                     disk name "EEDISK"

                     (With zero at the end)
# 0027 A 00 00 00 00 No following structure
                     tour (structure A

                     starts here)
# 002A D3 1F length of the

                     (# 2000 - # 002D)
# 002D / FF FF FF FF FF ...

                     blank area -

                     # 1FD3 bytes
# 1FFF FF last byte empty
                     the area of ​​memory
-----------------------------------------( C) 2002-08-28 Jarek 
Adamski {Zxvgs@yarek.com}, {http://zxvgs.yarek.com}