Service_USB 1 - Pipe requested exclusively
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## Name

Service_USB 1 - Pipe requested exclusively — Exclusive access to pipe requested

## On Entry

R0 | 1 (reason code)
R1 | &80C00 (USB Service call)
R2 | Pointer to controller structure
R3 | Pointer to device structure
R4 | Pointer to endpoint structure

## On Exit

All registers preserved to pass on else

R0 | 0 to refuse the exclusive claim or 1 to cause a re-try later
R1 | 0 to claim or preserved to pass on.
R2, R3, R4 | preserved

## Use

Must be broadcast by an application which wants to get to exclusive access to a shared pipe for operations which may damage the operation of the other applications on the same pipe. If rejected with a 1 result the application may wait for a Service_USB 0 and can afterwards retry to get the control. Note that a pointer to the endpoint structure must be passed because waiting programs are not having a pointer to the pipe structure.

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