FileSwitch Overview
Programmer's Reference Manuals
» Part 4 – Using Filing Systems
» FileSwitch
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Overview
FileSwitch is a module that is at the heart of all filing systems in RISC OS. It provides a common set of functions that is used by all filing systems. It only provides the parts of these services that are device-independent.
Any services that are device-specific are not provided by FileSwitch, but by separate modules.
Purpose of FileSwitch
Using a predefined interface, it notifies filing systems when they must do certain actions. It switches between currently active filing systems and keeps the state of each of them.
When filing systems are initialised they inform FileSwitch of three important pieces of information.
- Their name
- Where to find the routines for controlling the hardware
- Special actions that they can perform
Adding Filing Systems
Filing systems can be added to the Operating System easily by adding the relevant module to the system. As FileSwitch provides much of the common functionality, the filing system modules must provide the remaining functionality.
More detailed information on adding a filing system can be found in the Writing A Filing System? section.
Data Format
The data format of a filing system is not defined by the FileSwitch module. It only specifies what the user interface must look like.