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This makes it easier to automatically generate parts of the manager documentation in the future. Update #3993.
45 lines
1.8 KiB
ReStructuredText
45 lines
1.8 KiB
ReStructuredText
.. SPDX-License-Identifier: CC-BY-SA-4.0
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.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
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Operations
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==========
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Creating a Port
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---------------
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The ``rtems_port_create`` directive creates a port into a DPMA with the
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user-defined name. The user specifies the association between internal and
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external representations for the port being created. RTEMS allocates a
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Dual-Ported Memory Control Block (DPCB) from the DPCB free list to maintain the
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newly created DPMA. RTEMS also generates a unique dual-ported memory port ID
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which is returned to the calling task. RTEMS does not initialize the
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dual-ported memory area or access any memory within it.
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Obtaining Port IDs
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------------------
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When a port is created, RTEMS generates a unique port ID and assigns it to the
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created port until it is deleted. The port ID may be obtained by either of two
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methods. First, as the result of an invocation of the``rtems_port_create``
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directive, the task ID is stored in a user provided location. Second, the port
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ID may be obtained later using the ``rtems_port_ident`` directive. The port ID
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is used by other dual-ported memory manager directives to access this port.
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Converting an Address
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---------------------
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The ``rtems_port_external_to_internal`` directive is used to convert an address
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from external to internal representation for the specified port. The
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``rtems_port_internal_to_external`` directive is used to convert an address
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from internal to external representation for the specified port. If an attempt
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is made to convert an address which lies outside the specified DPMA, then the
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address to be converted will be returned.
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Deleting a DPMA Port
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--------------------
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A port can be removed from the system and returned to RTEMS with the
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``rtems_port_delete`` directive. When a port is deleted, its control block is
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returned to the DPCB free list.
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