Squash (RISC OS)
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* [http://acorn.riscos.com/riscos3/37/37DiscImage/Manuals/Manual/BOOK2AB/E_18.HTM Manual page] in the RISC OS 3.7 user guide | * [http://acorn.riscos.com/riscos3/37/37DiscImage/Manuals/Manual/BOOK2AB/E_18.HTM Manual page] in the RISC OS 3.7 user guide | ||
* [http://mdfs.net/Docs/Comp/Acorn/Filetypes The Unofficial Acorn Filetypes List] | * [http://mdfs.net/Docs/Comp/Acorn/Filetypes The Unofficial Acorn Filetypes List] | ||
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Revision as of 03:05, 13 June 2013
Overview
Squash files (file type FCA, Squash) contain compressed data for single files on RISC OS systems.
Format
According to the help text for the Squash application, "The Squash module currently compresses using a 12-bit LZW algorithm but no guarantee is made that this will be so in the future."
The compressed data is preceded by a header, with offsets measured in bytes and all values stored in little-endian byte order:
| Offset | Description |
|---|---|
| 0 | "SQSH" (4 byte ID) |
| 4 | Length of the original, uncompressed file in bytes |
| 8 | Load address of the original file |
| 12 | Execution address of the original file |
| 16 | Reserved (should be 0) |
As with a number of data formats related to filing systems on RISC OS, the load and execution addresses are actually used to hold the file type and date stamp of the original file.
References
- Help file for the Squash application
- Manual page in the RISC OS 3.7 user guide
- The Unofficial Acorn Filetypes List
