Showing changes from revision #2 to #3:
Added | Removed | Changed
Entry | |
---|---|
R0 | 2 |
R1 | Filing system number |
R2 | Pointer to media name |
R3 | Device number |
R4 | Iteration count |
R5 | Timeout delay |
R6 | Pointer to media type |
Exit | |
---|---|
R0 | 0 if medium change, or -1 if medium no longer required, else preserved |
R1 | Preserved |
R2 | Preserved |
R3 | Preserved |
R4 | Preserved |
R5 | Preserved |
R6 | Preserved |
The purpose of this call is to call warn applications that a filing medium is not known.
This Upcall is called when a media change (eg (e.g. another disc) is required.
The following information applies to both OS_UpCall 1 & OS_UpCall 2.
Any routines on this vector should:
When you intercept the call to the vector, control passes back to the filing system routine that called OS_UpCall…
The timeout period in R5 is set to a small value for media that can detect when the medium has been changed (such a floppy disc drives) and to a large value (typically &FFFFFFFF) for other media. In the former case, this means that RISC OS will automatically detect that a new medium has been supplied, and check that it is the correct one.
If R1 is unchanged on exit, nobody handled the request. In general general, this should be treated by filing systems as the media not present error.
The most common use of OS_UpCall 1 and 2 are to request that a floppy disc is inserted.