Squish is a compression program, it uses variations of the Byte & Counter method of Compression. It is best used for screens and sprites.
To use, drag the Sprite file to the icon, on the iconbar. A savebox will then pop up and you can save in the standard RISC OS manner. The output file will have the Filetype 156 : "Squished".
To decompact the file just drag the squished file to the icon and it will save as a sprite.
Description of the Menus & Windows
----------------------------------
The Main menu has the following options:
Info - The common info window
Options - Produces the options window; see below
Quit - Quits the program
The Options window has the following options:
Sprite Header - refers to whether the compressed input file is a
compressed screen or a compressed spritefile. It has a
default value of on, ie the file is a sprite.
Mode - Greyed-out unless Sprite Header is clicked off. This
refers to the screen mode which the screen has being saved
in. Default value 13.
Squish Header - Refers to a byte header, telling the program which
algorithm is used. It is advised to leave this option on,
unless decompacting sprites from games. Default ON.
Byte & Counter - Tells the program to decompress and to compress as Byte
and Counter.
Modification - Tells the program to decompress using the Byte & Counter
Modification (Found in games such as Superpool, 2067 BC)
Counter & Byte - Tells the program to decompress and to compress as Counter
and Byte.
Modification - Tells the program to compress using the Lodge Modification
(derived by Me!)
Lempel-Ziv-Welch- Tells the program to use the LZW alogorithm. This is not
currently supported in this version.
Huffman Encoding- Tells the program to use Huffman Encoding. This is not
currently supported in this version.
The default method is the Byte & Counter Algorithm
Compression Algorithms
----------------------
Byte then Counter (aka Run Length Encoding): The simplest form of compaction. The routine takes a byte from the file and finds how many time this is replicated. It then stores the byte and then the amount of times it occurs (ie the counter)
Counter then Byte: Like byte then counter, but the counter is stored before the byte.
Key Modification: Primarily a byte and counter method, but if a byte is found by itself, it is put straight to the disc, if a byte replicates, then the byte is put TWICE to the disc, followed by the counter. Note: not as yet avaiable to compress, instead, the program will use normal byte and counter.
Lodge Modification: Primarily a counter and byte method, but if more than two bytes which are NOT equal are found then they are put to the disc, prefixed and suffixed by a CHR$255 (ie ÿ). This imposes a limit on the counter ie 254.
File format
-----------
With header: 1 byte to tell algorithm: 0 - Byte and Counter
1 - Counter and Byte
2 - Key Modification
3 - Lodge Modification
Using this program in other programs
------------------------------------
Use the 'SquishMod' module SWIs as documented in the 'Tech' file in the program directory.
Riscy Developments (Dave Lodge / Ian Jeffray) accept no responsibility for the consequences of using this module : Use it as you wish : we don't really care!
Other points to note
--------------------
Certain games have used a similar compression technique (for all these files, Squish header should be turned OFF):
Nevryon: All files in the '1','2','3' and '4', called 'SHIPS' or 'SHIPS2' are compressed by a very similar technique, to decompress them and get the sprite files out, just change the filetype and drag them onto the !Squish icon, the resulting file will be a Sprite file, which you can load into Paint and mess around with. Most of the files in the PIX directory, can be dragged into the program, but you must ensure that the option "Sprite Header" is clicked OFF.
Saloon Cars Deluxe: There are various Byte & Counter compressed pictures in this, eg the map files in the Track directories. You must ensure the the option "Sprite Header" is clicked OFF.
2067 BC: All files in the Graphix directory, with the filetype &CCC (dietsprite) can be dragged straight into Squish, and will be converted.
TBVG: As above.
SuperPool, Break 147: All files in the !DeData.SCNSHOTS directory can be converted. These are stored using a variant of the Key Modification (which v2.42 of Squish can understand). To decompact them, filetype them to &CCC (dietsprite), and drag them into Squish. As they are all screens without the sprite header, it is advised to switch the Sprite Header option off.
Version Updates
---------------
v1.00 Original Icon Bar version
v2.00 Rewritten, with menus, info window and save box
v2.10 Rewritten with option window
v2.20 Diet Sprite compatibility offered
v2.21 Fix to stop crashing upon finding a null counter
v2.22 Doesn't crash with files which the output file turns out larger than
160k
v2.30 'Lodge' Modification added for better compression.
v2.31 Header added to Squish file: 1 byte = Method
v2.32 Adaption to Key modification to allow it to read Super Pool
Graphics and bug fix for loading screens more than current screen
memory.
v2.40 Module coded and added to program (Thanks Ian!)
v2.41 Module now used to fill Icons
v2.42 Compression now occurs when saving rather than loading.
Contacts
--------
If you want to contact me in any way, shape or form, or for any reason, then contact me at the addresses below:
Holidays: Dave Lodge
26 Cleveland Way
Carlton Miniott
Thirsk
N. Yorks.
YO7 4LN
Please enclose a SAE, if you expect a reply (I'm only a Student). Money, and offers of Alcoholic Beverages gratefully accepted!
Squish version 2.42 by Dave Lodge of Riscy Developments
(F) Floppyright 4th October 1992
PS Look out for more Riscy Developments programs at your local PD
library. We might actually get around to finishing writing our High
Score Editor one day!
PPS I am sorry about the Riscy Developments sprite on the info window
being done in mode 27, but if you can't afford a multisync monitor,
