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Filter_RegisterPreFilter
Programmer's Reference Manuals
» Part 7 - The Desktop
» The Filter Manager
» SWI Calls
» Filter_RegisterPreFilter
Filter_RegisterPreFilter
(SWI &42640)
| Entry | |
|---|---|
| R0 | Pointer to zero terminated filter name |
| R1 | Address of Pre Filter Code |
| R2 | Value to be passed to R12 |
| R3 | Task handle of task to which filter is applied, or 0 for all tasks |
| Exit |
|---|
| All registers preserved |
Use
The purpose of this call is to add a new filter to the list of pre-filters.
Notes
The address pointed to by R1 will be called whenever the task who’s handle is passed in R3 calls Wimp_Poll with R12 equal to the value of R2 when this SWI is called.
The routine pointed to by R1 will be called with:
|_<^. Entry | |
|<^. R0 |<^. Event mask as passed to Wimp_Poll|
|<^. R1 |<^. Pointer to Event block as passed to Wimp_Poll|
|<^. R2 |<^. Task handle of task that called Wimp_Poll|
| Exit |
|---|
| It may clear bits in r0 to provide a new event mask |
| It must preserve all other registers |