.. SPDX-License-Identifier: CC-BY-SA-4.0

.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)

Directives
==========

This section details the dual-ported memory manager's directives.  A subsection
is dedicated to each of this manager's directives and describes the calling
sequence, related constants, usage, and status codes.

.. raw:: latex

   \clearpage

.. index:: create a port
.. index:: rtems_port_create

.. _rtems_port_create:

PORT_CREATE - Create a port
---------------------------

CALLING SEQUENCE:
    .. code-block:: c

        rtems_status_code rtems_port_create(
            rtems_name  name,
            void       *internal_start,
            void       *external_start,
            uint32_t    length,
            rtems_id   *id
        );

DIRECTIVE STATUS CODES:
    .. list-table::
     :class: rtems-table

     * - ``RTEMS_SUCCESSFUL``
       - port created successfully
     * - ``RTEMS_INVALID_NAME``
       - invalid port name
     * - ``RTEMS_INVALID_ADDRESS``
       - address not on four byte boundary
     * - ``RTEMS_INVALID_ADDRESS``
       - ``id`` is NULL
     * - ``RTEMS_TOO_MANY``
       - too many DP memory areas created

DESCRIPTION:
    This directive creates a port which resides on the local node for the
    specified DPMA.  The assigned port id is returned in id.  This port id is
    used as an argument to other dual-ported memory manager directives to
    convert addresses within this DPMA.

    For control and maintenance of the port, RTEMS allocates and initializes an
    DPCB from the DPCB free pool.  Thus memory from the dual-ported memory area
    is not used to store the DPCB.

NOTES:
    This directive may cause the calling task to be preempted due to an
    obtain and release of the object allocator mutex.

    The internal_address and external_address parameters must be on a four byte
    boundary.

.. raw:: latex

   \clearpage

.. index:: get ID of a port
.. index:: obtain ID of a port
.. index:: rtems_port_ident

.. _rtems_port_ident:

PORT_IDENT - Get ID of a port
-----------------------------

CALLING SEQUENCE:
    .. code-block:: c

        rtems_status_code rtems_port_ident(
            rtems_name  name,
            rtems_id   *id
        );

DIRECTIVE STATUS CODES:
    .. list-table::
     :class: rtems-table

     * - ``RTEMS_SUCCESSFUL``
       - port identified successfully
     * - ``RTEMS_INVALID_ADDRESS``
       - ``id`` is NULL
     * - ``RTEMS_INVALID_NAME``
       - port name not found

DESCRIPTION:
    This directive obtains the port id associated with the specified name to be
    acquired.  If the port name is not unique, then the port id will match one
    of the DPMAs with that name.  However, this port id is not guaranteed to
    correspond to the desired DPMA.  The port id is used to access this DPMA in
    other dual-ported memory area related directives.

NOTES:
    This directive will not cause the running task to be preempted.

.. raw:: latex

   \clearpage

.. index:: delete a port
.. index:: rtems_port_delete

.. _rtems_port_delete:

PORT_DELETE - Delete a port
---------------------------

CALLING SEQUENCE:
    .. code-block:: c

        rtems_status_code rtems_port_delete(
            rtems_id id
        );

DIRECTIVE STATUS CODES:
    .. list-table::
     :class: rtems-table

     * - ``RTEMS_SUCCESSFUL``
       - port deleted successfully
     * - ``RTEMS_INVALID_ID``
       - invalid port id

DESCRIPTION:
    This directive deletes the dual-ported memory area specified by id.  The
    DPCB for the deleted dual-ported memory area is reclaimed by RTEMS.

NOTES:
    This directive may cause the calling task to be preempted due to an
    obtain and release of the object allocator mutex.

    The calling task does not have to be the task that created the port.  Any
    local task that knows the port id can delete the port.

.. raw:: latex

   \clearpage

.. index:: convert external to internal address
.. index:: rtems_port_external_to_internal

.. _rtems_port_external_to_internal:

PORT_EXTERNAL_TO_INTERNAL - Convert external to internal address
----------------------------------------------------------------

CALLING SEQUENCE:
    .. code-block:: c

        rtems_status_code rtems_port_external_to_internal(
            rtems_id   id,
            void      *external,
            void     **internal
        );

DIRECTIVE STATUS CODES:
    .. list-table::
     :class: rtems-table

     * - ``RTEMS_INVALID_ADDRESS``
       - ``internal`` is NULL
     * - ``RTEMS_SUCCESSFUL``
       - successful conversion

DESCRIPTION:
    This directive converts a dual-ported memory address from external to
    internal representation for the specified port.  If the given external
    address is invalid for the specified port, then the internal address is set
    to the given external address.

NOTES:
    This directive is callable from an ISR.

    This directive will not cause the calling task to be preempted.

.. raw:: latex

   \clearpage

.. index:: convert internal to external address
.. index:: rtems_port_internal_to_external

.. _rtems_port_internal_to_external:

PORT_INTERNAL_TO_EXTERNAL - Convert internal to external address
----------------------------------------------------------------

CALLING SEQUENCE:
    .. code-block:: c

        rtems_status_code rtems_port_internal_to_external(
            rtems_id   id,
            void      *internal,
            void     **external
        );

DIRECTIVE STATUS CODES:
    .. list-table::
     :class: rtems-table

     * - ``RTEMS_INVALID_ADDRESS``
       - ``external`` is NULL
     * - ``RTEMS_SUCCESSFUL``
       - successful conversion

DESCRIPTION:
    This directive converts a dual-ported memory address from internal to
    external representation so that it can be passed to owner of the DPMA
    represented by the specified port.  If the given internal address is an
    invalid dual-ported address, then the external address is set to the given
    internal address.

NOTES:
    This directive is callable from an ISR.

    This directive will not cause the calling task to be preempted.