Amiga Tools 2/Amiga Tools 2.iso/tools/packer/s-pack/s-pack.doc

Text File | 1995-03-09 | 15KB | 365 lines

                            S - P A C K


    S-PACK compresses and packs disks, HD partitions, drawers, and files into
 as small a volume as possible.  It can be used as an archiver, HD Backup, for
 preparing files for data transmission, and anywhere space on disks needs to
 be used economically.


   CALLING S-PACK

   WorkBench:   Click the icon.
   CLI:         Enter "S-PACK", use RUN if you wish.

    there are no switches or tool types required.


   CREATING PACKS

   When S-Pack is called a requester will appear.  At the top are four mode
  buttons, one for each of the available modes:

   PACK:    Click if you are going to make a new Pack.

   UNPACK:  Click if you want to unpack an existing Pack.

   LIST:    Click to extract the index from a Pack.

   EXTRACT: Click to extract a single file from a PACK.


   Below these are four string gadgets.  When a mode gadget is switched on
  any string gadgets not required for that mode will be ghosted.

   FILES:   used in Pack and Extract.

      Pack mode:    enter the disk, HD partition, drawer or file to be packed.

      Extract mode: enter the file to be extracted .  Filename should be
                    written as it appears in the index, however it is not
                    case-sensitive and the wildcard `?' is recognised.

    Clicking the button just to the left of the gadget will bring up a file
    requester if you have either Arp.library or ASL.library.


   PACKFILE: used in all modes.

     Pack mode:   Enter name and path for the pack; the programme will add
                .PACK  or .SE to the name that you enter here, according to
                whether the Pack is self-unpacking or not.  If a floppy
                drive is called put a disk - normally empty - in the required
                drive, and quote the drive name (eg df1:) rather than the disk
                name.  Existing data on the disk will NOT be deleted.

     Unpack/List/Extract:  Enter the full name and path to the Pack,
                INCLUDING ANY TERMINATING .PACK or .SE.  If unpacking or
                getting an index from floppies put the LAST disk of the pack
                in whatever drive is designated.

     A button is again provided for a file requester.  The output may need to
    be modified to ensure that floppies are referred to by drive and not name
    (for multi-disk packs).


   TO: used in Unpack, List and Extract

     Unpack mode:  Destination for the unpacked files.   Entry can be a
                disk, HD partition or drawer.  If a disk or HD partition you
                MUST end with ":".  If just a name is entered the program
                will open a drawer of that name on the Current Directory,
                and use that.   Default destination is a drawer "Output"
                opened in the current directory.

     List mode:    Enter filename and path for the extracted index.  Default
                is "RAM:List".

     Extract mode: Destination for the extracted file.  May be a disk, HD
                partition or drawer.  Comments at Unpack mode above apply.
                Default is "RAM:Extract"

     A button is provided for a file requester.  Again modify the output
    if necessary to ensure that floppies are referred to by drive, not name.


   TEMP FILES:     can be used in all modes.

     When packing or unpacking heavy use is made of intermediate files,
    by default opened in RAM:T.  Where ram is limited it can be useful to
    shuffle these temporary files off to a disk or HD partition.  Enter the
    required drive or partition here, terminating with ":".  The programme
    will add "T" to the drive and if necessary open the new drawer.


   Below these string gadgets are four more buttons:

    OK:  Accepts the entries and executes.

    SE:  Used only when Packing.  Adds a self-unpacking header (6590 bytes)
        and turns the pack into an executable programme.

    RECOMP:  Used only during Packing.  If a file compressed with Power
        Packer or the standard P-Compress code is encountered it will be
        re-compressed using S-PACK's more efficient compressor (the same as
        the SuperC option of P-Compress2).  This will reduce the size of the
        completed pack.  On unpacking, such files will be decompressed and
        not restored to their original state.  This may be the normal option
        if S-Pack is being used as an Archiver.

          If RECOMP is NOT called the PACK will be a little larger, but on
        unpacking such files will reappear in their original PP'd or P-
        Compressed state.  This will be the normal option for Backup packs.

    CANCEL:  Clear any entries.

    To quit, click the close gadget in the top left corner.


  MULTIDISK operations.

    Of necessity any programme used for backing up a hard disk must be
   capable of filling and restoring multiple disks.  With S-Pack multi-
   disk archives can also be created (there is no fundamental difference
   between a Pack made for HD Backup and one made for an Archive).  During
   Packing a requester will call for a new disk when the current one is
   full - insert an empty disk, or if you want to end the operation click
   "Abort".  Insertion of a new disk will automatically be recognised.

    During other operations specific disks (Disk[n], first disk, last disk)
   may be called.  Click "abort" or insert the required disk.  During
   unpacking the programme will call for a new disk if it finds that there
   is insufficient space on the current disk for the file that is being
   unpacked. (Calls for a new disk in a hard drive partition have to be
   ignored and the operation aborted).

     IF YOU WANT A MULTIDISK PACK TO HAVE AN ICON, YOU SHOULD PUT IT ON
     THE FIRST DISK OF THE PACK BEFORE YOU START TO CREATE THE PACK
     ITSELF.  (Otherwise there may be no room for it).

    Don't be in too much of a hurry when changing disks;  It is vital to
   wait for all disk activity to stop.


  UNPACKING.

   NON-SELF-UNPACKING PACKS:

    Call S-pack, If the pack is on floppies put the LAST disk of the pack in
   a floppy drive, click UNPACK and complete the requester.  The programme
   will first read the index, ask for the first disk, then start unpacking,
   calling for new disks as necessary.

   SELF-UNPACKING PACKS

    A self-unpacking executable will have been produced if the SE button was
   clicked when creating the pack, and can be identified by the .SE
   termination.  In effect the file on the first disk becomes an executable
   and calls continuation data from the remaining disks.

    To use an SE pack:
      If the pack is on floppies, put the FIRST disk of the pack in any drive.

    WORKBENCH:  Provide the file with a TOOL icon and set two ToolTypes:

     DEST=<DESTINATION>  Use upper-case, no gaps.  Enter the drive or drawer
                         into which you want to unpack. Default is ram:X.

           eg DEST=DF0:
           or DEST=HD5:apples  A drawer "apples" will be opened if necessary.

     TEMP=<TEMPDRIVE>    Use upper-case, no gaps.  Enter the drive to be
                         used for temporary files.  Default is ram:.  Do not
                         omit the `:'.

          eg TEMP=DF0:   Drawer DF0:T will be opened


    CLI:  Call the filename.  Include the terminating .SE if present.  Two
         switches are available matching the two tool-types above:

      -d<DESTINATION>  No gap between -d and drive, partition  or drawer.

      -t<TEMPDRIVE>    No gap again. Must be a drive or HD partition, not a
                         drawer.

           eg:  df2:HD5BackUp.SE -dHD5:apples -tHD4:

          This would unpack the file "HD5BackUp.SE" to HD5:apples, using
        HD4:T for temporary files.  Note the colons in HD5 and HD4; they
        must not be omitted.

        Defaults are the same, ram:X for destination and ram: for temps.

        If you type the name followed by  `?', eg df2:HDBackUp.SE ?, a
      Usage string "Usage: xxxx.SE -d<destination> -t<tempdrive>" will be
      printed to the screen.

    To otain the index for an SE pack, treat it like a non-SE pack - put the
   last disk in a drive, call S-Pack, click LIST and complete the requester.
   Single files cannot be extracted from an .SE pack.


  FLOPPY DISKS

    Disks are not re-formatted or re-named automatically, and the necessary
   number should be cleared and numbered before you start a Pack.  DO NOT
   FORMAT TO THE "FAST FILE SYSTEM" - writing to an FFS disk is a lot slower
   than to a normal disk!  For reasonable writing speed call sys:c/Addbuffers
   with as high a setting as you can afford; packing will be very slow if the
   normal default figure of 5 is left unchanged.  To ensure that follow-up
   disks in multi-disk packs can be recognised always use the DRIVE (eg df0:)
   not the diskNAME.


  DIALOGUE

    The output window will show the name of each file as it is packed or
   unpacked.

    During compression or decompression of large files the machine may be
   quiet for some time.  To indicate that work is in progress a dot will be
   printed out at intervals.


  SPEED.

   For maximum speed:

    The `ADDBUFFERS' setting should be as high as possible - desirably at
   least 100 for any drive or partition used.  This will of course benefit
   all IO, not just S-Pack.  Remember that each buffer costs you some 500
   bytes of ram.

    Use the Old File System, not FFS.

    If memory is tight, reboot.  This clears fragmentation and improves
   speed by maximising the memory available.

    Use RAM for the temporary files.  (Use a floppy only as a last resort).


  MEMORY CONTROL.

    S-PACK can use a lot of memory.  Consider the task of unpacking an .SE
   pack containing a single file of compressed size 1Mbyte (on two disks),
   expanding to 2Mbyte decompressed:

    When the file is called the whole executable - on the first disk - is
   loaded into memory like any other executable.   typically   840 Kbytes

    Then the two parts are assembled in a temporary file      1000 Kbytes

    Next provision for decompression is made:
                               filesize(compressed) +130K     1130 Kbytes

    If (for speed) you are unpacking to ram:       add        2000 Kbytes

                                                   Total      4970 Kbytes

    This can be reduced to some 1.14 Mbytes:

   1. Reduce the size of the executable part (it must have at least the SE
    header and the start of the first file to be included in the pack - say
    8000 bytes) to a minimum by filling all but some 8000 bytes with rubbish
    before creating the pack, then delete the rubbish.  Saves  832 Kbytes.

   2  Locate temporary files anywhere there is 1Mbyte to spare - a hard
     disk partition.  A floppy could be used for smaller files but would
     slow operations considerably.                      Saves 1000 Kbytes

   3. Pack/Unpack directly to the final destination.    Saves 2000 Kbytes.

    If these steps are taken (where relevant) calculate memory usage as:

      Unpack
         130K + largest file (compressed size).

      Pack
         300K + largest file (uncompressed size)

   but allow as large a safety factor as you can to ensure that problems
   with fragmented memory are avoided.


  RECOVERY

    One of the features of S-PACK is the ability to recover the bulk of data
   even if one of the disks in the pack develops a fault.  Disks prior to
   the faulty one should unpack correctly.

    First run the damaged disk through DISKSALV or a similar recovery
   programme, and try to unpack again.

    If still faulty, extract the index.  This will always be possible if the
   last disk is OK, and MAY be possible even if there is a fault on this disk.

    Using the index and the EXTRACT option of S-PACK extract files from disks
   following the faulty disk (non-SE packs only).

    If the faulty disk can be read at all use the EXTRACT option to get as
   many files from it as possible (non-SE packs only).  Success will depend
   on the precise nature of the fault.

    Finally try to load the faulty disk into one of the programmes that
   allow hex files to be read and written to, and allow the extraction of
   sections of a file (HEX, BEAV, FILEMASTER). If the pack file on the disk
   can be loaded, individual files can be extracted using this format data:

     The format of each file is:

     Marker:            FI (2 bytes)
                        serial number (2 bytes). Bit 15 will be set if the
                          file is not compressed.

     Uncompressed file:
                        size (4 bytes)
                        data
       To extract the file just copy the data section to a new file.

     Compressed file:
                        uncompressed size (4 bytes)
                        compressed size (4 bytes)
                        crc (2 bytes)
                        data
       To extract the file copy the whole to a new file and change the first
      4 bytes (marker + serial number) from FIxx to HILH.  You now have a file
      which can be de-compressed by P-Compress2, or if a text can be read by
      and saved in clear from the latest version of P-Reader. (V7.1).
      Alternatively S-PACK the extracted file using the "RECOMP" option and
      then unpack it.

     Finally, even if the disk itself is damaged so severely that the PACK
    file on it cannot be read as a file, it should still be possible to
    extract sectors using Nic Wison's TRACKDOS and to reconstitute individual
    files from these.  This is not easy.




           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


   The compression code used is based on that used in Matthias Meixner's
  SHRINK archiver, modified to improve speed.  A large measure of the
  credit for S-Pack's performance should be given to Matthias Meixner for
  this extremely efficient code.

   S-Pack is Freeware.  It may be copied and distributed freely and used
  without charge for non-commercial purposes.  Authority for commercial
  use should be obtained from the author below.

   No responsibility can be accepted for any loss occasioned by use of the
  programme.


  Chas A. Wyndham,
  1265 Canning Mills Road,
  Roleystone,
  WA 6111.
  Australia