SquashApp - Squashes RunImage programs

by Alex Hayward


SquashApp compresses an application's !RunImage file using the Squash module, and alters its !Run file to transparently decompress and run the application when it is double-clicked on.

In order for compression and decompression to take place the utility Squash, found inside the Squash application on RISC OS 3 Applications Disc 1, must be copied to your library directory. This should normally be present in the root directory of your hard disc and called Library. It is not recommended that you use this application from floppy disc, or you will have to do a lot of disc-swapping. It is possible to set any directory to be the library directory with the *Lib command, or by setting the environment variable Run$Path, using the following commands:
  Lib <full directory name>
or
  Set Run$Path <Run$Path>,<full directory name>.
Note the trailing dot after the last command. In the unlikely situation that the latter does not work, try the Lib command instead. Whichever command you use, it can be placed in your !Boot file to make sure it is set up every time you use your computer.

If you have a Risc PC, a library will already exist. Open the root directory of your machine, then hold down Shift while you double-click on !Boot. There is a directory in !Boot called Library into which you should save the Squash utility.

To compress an application, you must first load SquashApp by double-clicking on the !SquashApp icon in a directory display or by clicking on its icon in the Risc User Menu program. Then drag any application you want to squash onto the SquashApp icon, but make a copy first in case something goes wrong. The application will be compressed and its !Run file replaced with a new version which will decompress the !RunImage file on the fly each time it is run in future. The original !Run file is saved as Old!Run in case you want to retrieve it at any time.

If an applications !RunImage file cannot be compressed it is left unaltered. The compression generally works better with Basic programs than it does with compiled or assembled code, since these are often already compressed using Acorn's Squeeze utility.

A temporary scrap file is used for decompression so there must be enough room on the disc to hold the original uncompressed file, and the Filer must have seen the !Scrap directory. Note that there will not be enough room on this disc to decompress an application, so if it is the only !Scrap directory set up, you should first copy !Scrap into the root directory of your hard disc and then run the new copy.


 Copyright RISC User 1994
