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diff --git a/c-user/dual_ports_memory_manager.rst b/c-user/dual_ports_memory_manager.rst deleted file mode 100644 index a8b7183..0000000 --- a/c-user/dual_ports_memory_manager.rst +++ /dev/null @@ -1,313 +0,0 @@ -.. SPDX-License-Identifier: CC-BY-SA-4.0 - -.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) - -.. index:: ports -.. index:: dual ported memory - -Dual-Ported Memory Manager -************************** - -Introduction -============ - -The dual-ported memory manager provides a mechanism for converting addresses -between internal and external representations for multiple dual-ported memory -areas (DPMA). The directives provided by the dual-ported memory manager are: - -- rtems_port_create_ - Create a port - -- rtems_port_ident_ - Get ID of a port - -- rtems_port_delete_ - Delete a port - -- rtems_port_external_to_internal_ - Convert external to internal address - -- rtems_port_internal_to_external_ - Convert internal to external address - -.. index:: dual ported memory, definition -.. index:: external addresses, definition -.. index:: internal addresses, definition - -Background -========== - -A dual-ported memory area (DPMA) is an contiguous block of RAM owned by a -particular processor but which can be accessed by other processors in the -system. The owner accesses the memory using internal addresses, while other -processors must use external addresses. RTEMS defines a port as a particular -mapping of internal and external addresses. - -There are two system configurations in which dual-ported memory is commonly -found. The first is tightly-coupled multiprocessor computer systems where the -dual-ported memory is shared between all nodes and is used for inter-node -communication. The second configuration is computer systems with intelligent -peripheral controllers. These controllers typically utilize the DPMA for -high-performance data transfers. - -Operations -========== - -Creating a Port ---------------- - -The ``rtems_port_create`` directive creates a port into a DPMA with the -user-defined name. The user specifies the association between internal and -external representations for the port being created. RTEMS allocates a -Dual-Ported Memory Control Block (DPCB) from the DPCB free list to maintain the -newly created DPMA. RTEMS also generates a unique dual-ported memory port ID -which is returned to the calling task. RTEMS does not initialize the -dual-ported memory area or access any memory within it. - -Obtaining Port IDs ------------------- - -When a port is created, RTEMS generates a unique port ID and assigns it to the -created port until it is deleted. The port ID may be obtained by either of two -methods. First, as the result of an invocation of the``rtems_port_create`` -directive, the task ID is stored in a user provided location. Second, the port -ID may be obtained later using the ``rtems_port_ident`` directive. The port ID -is used by other dual-ported memory manager directives to access this port. - -Converting an Address ---------------------- - -The ``rtems_port_external_to_internal`` directive is used to convert an address -from external to internal representation for the specified port. The -``rtems_port_internal_to_external`` directive is used to convert an address -from internal to external representation for the specified port. If an attempt -is made to convert an address which lies outside the specified DPMA, then the -address to be converted will be returned. - -Deleting a DPMA Port --------------------- - -A port can be removed from the system and returned to RTEMS with the -``rtems_port_delete`` directive. When a port is deleted, its control block is -returned to the DPCB free list. - -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. |