Description

   This routine performs a SCSI Move Medium command, or equivalent
   if some other I/O architecture is supported. It is used by mrd_
   move(3mrd), mrd_load(3mrd), mrd_unload(3mrd), mrd_inject(3mrd)
   and mrd_eject(3mrd). Since it accepts a robot_info_t structure
   associated with an open medium changer it can be used to perform
   multiple move commands, without having to re-open the medium
   changer as the other functions that use it do.

   The robot_info argument is the address of a robot_info_t that
   has been opened by mrd_startup(3mrd). If the medium changer isn't
   opened, the Move Medium command will fail with the operating
   system error for trying to use an unopened device. On SCSI medium
   changers, it maps directly to the SCSI Move Medium command.

   The transport address is the absolute address of the transport
   element to be used for the command. Many medium changers allow
   the use of address zero (0) as the default transport, but some
   may require a transport address that is valid for the medium
   changer. For single transport medium changers, the transport
   base address in the robot_info_t structure, transport_start is a
   suitable address.

   The source and destination addresses are absolute addresses to
   be used as the source and destination for the move. The absolute
   address can be calculated from a zero relative address by adding
   it to the base address for the element type. The routine makes
   no checks for the validity of the address, relying on the medium
   changer to do this.

   A invert value of one (1) can be used on medium changers that
   support inverting the media, when this is desired; an optical
   drive with two sided media. Otherwise a value of zero should be
   used.

   This routine uses the dev_status_t structure for handing errors.
   The dev_status_t structure includes the code, os_status, and SCSI
   error fields. The following describes how to decode errors with
   the dev_status_t structure.

   SCSI Errors

   SCSI errors are indicated when the value of the valid field of
   the SCSI error is not equal to 0. The key, asc, and ascq fields
   provide additional information to help determine the cause of the
   error.

   The code usually maps the Additional Sense Code and Additional
   Sense Code Qualifier (ASC/ASCQ) values to an MRD error. The asc
   and ascq values are copied from the request sense data returned
   by the target.

   The Additional Sense Code (asc) indicates further information
   related to the error or exception condition reported in the sense
   key field. The Additional Sense Code Qualifier (ascq) indicates
   detailed information related to the additional sense code. For
   more information, consult the SCSI-2 Specification.

   Operating System Errors

   Operating system errors are indicated when the value of the valid
   field of the SCSI error is equal to 0 and the value of the os_
   status field is not equal to 0. This result is most likely caused
   by an operating system error, and probably has a mapped error in
   MRD.

   MRD Errors

   MRD errors are indicated when the value of the os_status field is
   0, and the value of the valid field of the SCSI error is 0. This
   result is most likely caused when MRD encounters its own failure.