The TPU$TRIGGER_ASYNC_ACTION routine allows applications using
    the DECTPU full callable interface to interrupt the DECTPU
    TPU$CONTROL loop at an asynchronous level.

    Format

      TPU$TRIGGER_ASYNC_ACTION  facility_index

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

    Longword condition value. Most utility routines return a
    condition value in R0. Condition values that this routine can
    return are listed under Condition Values Returned.

2  –  Arguments

 facility_index

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    The facility_index argument represents the asynchronous action to
    be taken. This is the same index passed to the TPU$SPECIFY_ASYNC_
    ACTION routine registering what DECTPU statements to execute.

3  –  Description

    The TPU$TRIGGER_ASYNC_ACTION routine, along with TPU$SPECIFY_
    ASYNC_ACTION routine allow applications to interrupt DECTPU after
    calling TPU$CONTROL. The command that was specified for this
    facility_index is put on the DECTPU queue of work items and is
    handled as soon as no other work items are present. This allows
    DECTPU to complete and stabilize its environment before executing
    the command. This routine must be called after control has been
    passed to DECTPU via the TPU$CONTROL routine.

4  –  Condition Values Returned

    TPU$_SUCCESS       Normal successful completion.
    TPU$_UNKFACILITY   The facility_index passed to this routine
                       does not match any facility index passed to
                       TPU$SPECIFY_ASYNC_ACTION.