Archive - Compression - Join - Split Files



Menu Level

Why Needed

Description





1 Split SubSub Some Files are
  • Too big to send by email
  • Too big to store on USB FAT32 stick
     
    • Splits by a designated size
    • incorporates a SHA1 Hash to enable the files to be checked
    • extension -
    • 0slar holds split file details
      • Number of Splits
      • Slit size
      • last Split size
      • SHA1 for each split
    • 1slar to  "last Number"slar holds data
2 Join SubSub Need to joins files that have been split by "1 Split" routine

  • Joins Files that have been split by "1 Split"
  • Checks that files have not been altered using a stored SHA1 hash
3 Check Split Files SubSub Need to check FIles split by "1 Split" routine have not altered
  • Checks that files have not been altered using a stored SHA1 hash in the split files
Three functions (Split, Join, Check Split Files) above are related
4 Compress SubSub Some Files are
  • Too big to send by email
  • Too big to store on USB FAT32 stick
  • Need compressing to take up smaller space
  • Compresses files
  • Compresses and splits files if the file is too large
  • extension
    • ezp - compress for files less than 1000000
    • elzp - compress for files lager than 1Mb
    • 0lezp split compression
      • splits files into 1000000 parts with remainder
      • Has header
        • size
        • name
        • number of parts
        • SHA0 of file
5 De-Compress SubSub
  • De-compresses files according to extension
  • Checks that stored Hash of original file matches hash of decompressed file
6 Check Compressed Files SubSub
  • Checks that stored Hash of original file matches hash of decompressed file
7 Predict Compressed File Size SubSub
  • Makes an estimate of file if it were to compress.
8 Predict Uncompressed File Sizes SubSub

    • Make an estimate of what space a compressed file would take up
The five functions (Compress, De-Compress, Check Compressed Files, Predict Compressed File Size, Predict Uncompressed File Size) above are related
9 Join Files SubSub
  • All Files are allocated space on a hard drive.
  • Space files occupy is determined by sector size
  • Some File systems make allowance for sector size when allocating file pointers, but not all file systems do this
  • By joining lots of small files together space can be saved on hard drive
  • Joined files
  • Join Files can be left as they are
  • Joined Files can be Compressed
  • Joined Files can be encrypted
a Separate SubSub
  • Separate out files from joined files
  • Separate out files from joined files which have been compressed
  • Separate out files from joined files which have been encrypted
The two functions (Join Files, Separate) above are related