=> R0 = task handle of Filer
R1 = &49 (reason code)
<= R0 & R1 preserved to pass on else
<= R0 = pointer to command to start module
R1 = 0 (to claim service)
This service is issued by the Filer to start up resident filer module tasks by passing the returned command to Wimp_StartTask. Module tasks which wish to start should claim this service, passing their start command in R0. The Filer will re-issue this service until no more modules claim it.
To prevent infinite loops if an error occurs in starting a task, modules should:
1 set their taskhandle to 0 on initialise, Service_Reset or Service_StartedFiler
2 only claim this service if their taskhandle is zero (i.e. they are not already running, and not attempting to re-start)
3 set their taskhandle to a flag value (-1) when they claim this service
4a set their taskhandle based on the return result of Wimp_Initialise if their command is called
4b or set their taskhandle back to 0 on Service_StartedFiler (failed to initialise)
5 set their taskhandle back to 0 when they quit using Wimp_CloseDown
Filer tasks should also check for Service_FilerDying, and close down if they receive it.
See PRM 2, page 490
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