c-user: Split up semaphore manager

This makes it easier to automatically generate parts of the manager
documentation in the future.

Update #3993.

1 files changed, 0 insertions, 959 deletions

diff --git a/c-user/semaphore_manager.rst b/c-user/semaphore_manager.rst
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-.. SPDX-License-Identifier: CC-BY-SA-4.0
-
-.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
-
-.. index:: semaphores
-.. index:: binary semaphores
-.. index:: counting semaphores
-.. index:: mutual exclusion
-
-Semaphore Manager
-*****************
-
-Introduction
-============
-
-The semaphore manager utilizes standard Dijkstra
-counting semaphores to provide synchronization and mutual
-exclusion capabilities.  The directives provided by the
-semaphore manager are:
-
-- rtems_semaphore_create_ - Create a semaphore
-
-- rtems_semaphore_ident_ - Get ID of a semaphore
-
-- rtems_semaphore_delete_ - Delete a semaphore
-
-- rtems_semaphore_obtain_ - Acquire a semaphore
-
-- rtems_semaphore_release_ - Release a semaphore
-
-- rtems_semaphore_flush_ - Unblock all tasks waiting on a semaphore
-
-- rtems_semaphore_set_priority_ - Set priority by scheduler for a semaphore
-
-Background
-==========
-
-A semaphore can be viewed as a protected variable whose value can be modified
-only with the ``rtems_semaphore_create``, ``rtems_semaphore_obtain``, and
-``rtems_semaphore_release`` directives.  RTEMS supports both binary and
-counting semaphores. A binary semaphore is restricted to values of zero or one,
-while a counting semaphore can assume any non-negative integer value.
-
-A binary semaphore (not a simple binary semaphore) can be used to control
-access to a single resource.  In particular, it can be used to enforce mutual
-exclusion for a critical section in user code (mutex).  In this instance, the
-semaphore would be created with an initial count of one to indicate that no
-task is executing the critical section of code.  Upon entry to the critical
-section, a task must issue the ``rtems_semaphore_obtain`` directive to prevent
-other tasks from entering the critical section.  Upon exit from the critical
-section, the task that obtained the binary semaphore must issue the
-``rtems_semaphore_release`` directive to allow another task to execute the
-critical section.  A binary semaphore must be released by the task that
-obtained it.
-
-A counting semaphore can be used to control access to a pool of two or more
-resources.  For example, access to three printers could be administered by a
-semaphore created with an initial count of three.  When a task requires access
-to one of the printers, it issues the ``rtems_semaphore_obtain`` directive to
-obtain access to a printer.  If a printer is not currently available, the task
-can wait for a printer to become available or return immediately.  When the
-task has completed printing, it should issue the ``rtems_semaphore_release``
-directive to allow other tasks access to the printer.
-
-Task synchronization may be achieved by creating a semaphore with an initial
-count of zero.  One task waits for the arrival of another task by issuing a
-``rtems_semaphore_obtain`` directive when it reaches a synchronization point.
-The other task performs a corresponding ``rtems_semaphore_release`` operation
-when it reaches its synchronization point, thus unblocking the pending task.
-
-.. _Nested Resource Access:
-
-Nested Resource Access
-----------------------
-
-Deadlock occurs when a task owning a binary semaphore attempts to acquire that
-same semaphore and blocks as result.  Since the semaphore is allocated to a
-task, it cannot be deleted.  Therefore, the task that currently holds the
-semaphore and is also blocked waiting for that semaphore will never execute
-again.
-
-RTEMS addresses this problem by allowing the task holding the binary semaphore
-to obtain the same binary semaphore multiple times in a nested manner.  Each
-``rtems_semaphore_obtain`` must be accompanied with a
-``rtems_semaphore_release``.  The semaphore will only be made available for
-acquisition by other tasks when the outermost ``rtems_semaphore_obtain`` is
-matched with a ``rtems_semaphore_release``.
-
-Simple binary semaphores do not allow nested access and so can be used for task
-synchronization.
-
-.. _Priority Inheritance:
-
-Priority Inheritance
---------------------
-
-RTEMS supports :ref:`priority inheritance <PriorityInheritance>` for local,
-binary semaphores that use the priority task wait queue blocking discipline.
-In SMP configurations, the :ref:`OMIP` is used instead.
-
-.. _Priority Ceiling:
-
-Priority Ceiling
-----------------
-
-RTEMS supports :ref:`priority ceiling <PriorityCeiling>` for local, binary
-semaphores that use the priority task wait queue blocking discipline.
-
-.. _Multiprocessor Resource Sharing Protocol:
-
-Multiprocessor Resource Sharing Protocol
-----------------------------------------
-
-RTEMS supports the :ref:`MrsP` for local, binary semaphores that use the
-priority task wait queue blocking discipline.  In uniprocessor configurations,
-the :ref:`PriorityCeiling` is used instead.
-
-.. _Building a Semaphore Attribute Set:
-
-Building a Semaphore Attribute Set
-----------------------------------
-
-In general, an attribute set is built by a bitwise OR of the desired attribute
-components.  The following table lists the set of valid semaphore attributes:
-
-.. list-table::
- :class: rtems-table
-
- * - ``RTEMS_FIFO``
-   - tasks wait by FIFO (default)
- * - ``RTEMS_PRIORITY``
-   - tasks wait by priority
- * - ``RTEMS_BINARY_SEMAPHORE``
-   - restrict values to 0 and 1
- * - ``RTEMS_COUNTING_SEMAPHORE``
-   - no restriction on values (default)
- * - ``RTEMS_SIMPLE_BINARY_SEMAPHORE``
-   - restrict values to 0 and 1, do not allow nested access, allow deletion of
-     locked semaphore.
- * - ``RTEMS_NO_INHERIT_PRIORITY``
-   - do not use priority inheritance (default)
- * - ``RTEMS_INHERIT_PRIORITY``
-   - use priority inheritance
- * - ``RTEMS_NO_PRIORITY_CEILING``
-   - do not use priority ceiling (default)
- * - ``RTEMS_PRIORITY_CEILING``
-   - use priority ceiling
- * - ``RTEMS_NO_MULTIPROCESSOR_RESOURCE_SHARING``
-   - do not use Multiprocessor Resource Sharing Protocol (default)
- * - ``RTEMS_MULTIPROCESSOR_RESOURCE_SHARING``
-   - use Multiprocessor Resource Sharing Protocol
- * - ``RTEMS_LOCAL``
-   - local semaphore (default)
- * - ``RTEMS_GLOBAL``
-   - global semaphore
-
-Attribute values are specifically designed to be mutually exclusive, therefore
-bitwise OR and addition operations are equivalent as long as each attribute
-appears exactly once in the component list.  An attribute listed as a default
-is not required to appear in the attribute list, although it is a good
-programming practice to specify default attributes.  If all defaults are
-desired, the attribute ``RTEMS_DEFAULT_ATTRIBUTES`` should be specified on this
-call.
-
-This example demonstrates the attribute_set parameter needed to create a local
-semaphore with the task priority waiting queue discipline.  The attribute_set
-parameter passed to the ``rtems_semaphore_create`` directive could be either
-``RTEMS_PRIORITY`` or ``RTEMS_LOCAL | RTEMS_PRIORITY``.  The attribute_set
-parameter can be set to ``RTEMS_PRIORITY`` because ``RTEMS_LOCAL`` is the
-default for all created tasks.  If a similar semaphore were to be known
-globally, then the attribute_set parameter would be ``RTEMS_GLOBAL |
-RTEMS_PRIORITY``.
-
-Some combinatinos of these attributes are invalid.  For example, priority
-ordered blocking discipline must be applied to a binary semaphore in order to
-use either the priority inheritance or priority ceiling functionality.  The
-following tree figure illustrates the valid combinations.
-
-.. figure:: ../images/c_user/semaphore_attributes.png
-         :width: 90%
-         :align: center
-         :alt: Semaphore Attributes
-
-.. _Building a SEMAPHORE_OBTAIN Option Set:
-
-Building a SEMAPHORE_OBTAIN Option Set
---------------------------------------
-
-In general, an option is built by a bitwise OR of the desired option
-components.  The set of valid options for the ``rtems_semaphore_obtain``
-directive are listed in the following table:
-
-.. list-table::
- :class: rtems-table
-
- * - ``RTEMS_WAIT``
-   - task will wait for semaphore (default)
- * - ``RTEMS_NO_WAIT``
-   - task should not wait
-
-Option values are specifically designed to be mutually exclusive, therefore
-bitwise OR and addition operations are equivalent as long as each attribute
-appears exactly once in the component list.  An option listed as a default is
-not required to appear in the list, although it is a good programming practice
-to specify default options.  If all defaults are desired, the option
-``RTEMS_DEFAULT_OPTIONS`` should be specified on this call.
-
-This example demonstrates the option parameter needed to poll for a semaphore.
-The option parameter passed to the ``rtems_semaphore_obtain`` directive should
-be ``RTEMS_NO_WAIT``.
-
-Operations
-==========
-
-.. _Creating a Semaphore:
-
-Creating a Semaphore
---------------------
-
-The ``rtems_semaphore_create`` directive creates a binary or counting semaphore
-with a user-specified name as well as an initial count.  If a binary semaphore
-is created with a count of zero (0) to indicate that it has been allocated,
-then the task creating the semaphore is considered the current holder of the
-semaphore.  At create time the method for ordering waiting tasks in the
-semaphore's task wait queue (by FIFO or task priority) is specified.
-Additionally, the priority inheritance or priority ceiling algorithm may be
-selected for local, binary semaphores that use the priority task wait queue
-blocking discipline.  If the priority ceiling algorithm is selected, then the
-highest priority of any task which will attempt to obtain this semaphore must
-be specified.  RTEMS allocates a Semaphore Control Block (SMCB) from the SMCB
-free list.  This data structure is used by RTEMS to manage the newly created
-semaphore.  Also, a unique semaphore ID is generated and returned to the
-calling task.
-
-.. _Obtaining Semaphore IDs:
-
-Obtaining Semaphore IDs
------------------------
-
-When a semaphore is created, RTEMS generates a unique semaphore ID and assigns
-it to the created semaphore until it is deleted.  The semaphore ID may be
-obtained by either of two methods.  First, as the result of an invocation of
-the ``rtems_semaphore_create`` directive, the semaphore ID is stored in a user
-provided location.  Second, the semaphore ID may be obtained later using the
-``rtems_semaphore_ident`` directive.  The semaphore ID is used by other
-semaphore manager directives to access this semaphore.
-
-.. _Acquiring a Semaphore:
-
-Acquiring a Semaphore
----------------------
-
-The ``rtems_semaphore_obtain`` directive is used to acquire the
-specified semaphore.  A simplified version of the ``rtems_semaphore_obtain``
-directive can be described as follows:
-
-    If the semaphore's count is greater than zero then decrement the
-    semaphore's count else wait for release of semaphore then return
-    SUCCESSFUL.
-
-When the semaphore cannot be immediately acquired, one of the following
-situations applies:
-
-- By default, the calling task will wait forever to acquire the semaphore.
-
-- Specifying ``RTEMS_NO_WAIT`` forces an immediate return with an error status
-  code.
-
-- Specifying a timeout limits the interval the task will wait before returning
-  with an error status code.
-
-If the task waits to acquire the semaphore, then it is placed in the
-semaphore's task wait queue in either FIFO or task priority order.  If the task
-blocked waiting for a binary semaphore using priority inheritance and the
-task's priority is greater than that of the task currently holding the
-semaphore, then the holding task will inherit the priority of the blocking
-task.  All tasks waiting on a semaphore are returned an error code when the
-semaphore is deleted.
-
-When a task successfully obtains a semaphore using priority ceiling and the
-priority ceiling for this semaphore is greater than that of the holder, then
-the holder's priority will be elevated.
-
-.. _Releasing a Semaphore:
-
-Releasing a Semaphore
----------------------
-
-The ``rtems_semaphore_release`` directive is used to release the specified
-semaphore.  A simplified version of the ``rtems_semaphore_release`` directive
-can be described as follows:
-
-    If there are no tasks are waiting on this semaphore then increment the
-    semaphore's count else assign semaphore to a waiting task and return
-    SUCCESSFUL.
-
-If this is the outermost release of a binary semaphore that uses priority
-inheritance or priority ceiling and the task does not currently hold any other
-binary semaphores, then the task performing the ``rtems_semaphore_release``
-will have its priority restored to its normal value.
-
-.. _Deleting a Semaphore:
-
-Deleting a Semaphore
---------------------
-
-The ``rtems_semaphore_delete`` directive removes a semaphore from the system
-and frees its control block.  A semaphore can be deleted by any local task that
-knows the semaphore's ID.  As a result of this directive, all tasks blocked
-waiting to acquire the semaphore will be readied and returned a status code
-which indicates that the semaphore was deleted.  Any subsequent references to
-the semaphore's name and ID are invalid.
-
-Directives
-==========
-
-This section details the semaphore 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 semaphore
-.. index:: rtems_semaphore_create
-
-.. _rtems_semaphore_create:
-
-SEMAPHORE_CREATE - Create a semaphore
--------------------------------------
-
-
-CALLING SEQUENCE:
-    .. code-block:: c
-
-        rtems_status_code rtems_semaphore_create(
-            rtems_name           name,
-            uint32_t             count,
-            rtems_attribute      attribute_set,
-            rtems_task_priority  priority_ceiling,
-            rtems_id            *id
-        );
-
-DIRECTIVE STATUS CODES:
-    .. list-table::
-     :class: rtems-table
-
-     * - ``RTEMS_SUCCESSFUL``
-       - semaphore created successfully
-     * - ``RTEMS_INVALID_NAME``
-       - invalid semaphore name
-     * - ``RTEMS_INVALID_ADDRESS``
-       - ``id`` is NULL
-     * - ``RTEMS_TOO_MANY``
-       - too many semaphores created
-     * - ``RTEMS_NOT_DEFINED``
-       - invalid attribute set
-     * - ``RTEMS_INVALID_NUMBER``
-       - invalid starting count for binary semaphore
-     * - ``RTEMS_TOO_MANY``
-       - too many global objects
-
-DESCRIPTION:
-    This directive creates a semaphore which resides on the local node. The
-    created semaphore has the user-defined name specified in name and the
-    initial count specified in count.  For control and maintenance of the
-    semaphore, RTEMS allocates and initializes a SMCB.  The RTEMS-assigned
-    semaphore id is returned in id.  This semaphore id is used with other
-    semaphore related directives to access the semaphore.
-
-    Specifying PRIORITY in attribute_set causes tasks waiting for a semaphore
-    to be serviced according to task priority.  When FIFO is selected, tasks
-    are serviced in First In-First Out order.
-
-NOTES:
-    This directive may cause the calling task to be preempted due to an
-    obtain and release of the object allocator mutex.
-
-    The priority inheritance and priority ceiling algorithms are only supported
-    for local, binary semaphores that use the priority task wait queue blocking
-    discipline.
-
-    The following semaphore attribute constants are defined by RTEMS:
-
-    .. list-table::
-     :class: rtems-table
-
-     * - ``RTEMS_FIFO``
-       - tasks wait by FIFO (default)
-     * - ``RTEMS_PRIORITY``
-       - tasks wait by priority
-     * - ``RTEMS_BINARY_SEMAPHORE``
-       - restrict values to 0 and 1
-     * - ``RTEMS_COUNTING_SEMAPHORE``
-       - no restriction on values (default)
-     * - ``RTEMS_SIMPLE_BINARY_SEMAPHORE``
-       - restrict values to 0 and 1, block on nested access, allow deletion of locked semaphore.
-     * - ``RTEMS_NO_INHERIT_PRIORITY``
-       - do not use priority inheritance (default)
-     * - ``RTEMS_INHERIT_PRIORITY``
-       - use priority inheritance
-     * - ``RTEMS_NO_PRIORITY_CEILING``
-       - do not use priority ceiling (default)
-     * - ``RTEMS_PRIORITY_CEILING``
-       - use priority ceiling
-     * - ``RTEMS_NO_MULTIPROCESSOR_RESOURCE_SHARING``
-       - do not use Multiprocessor Resource Sharing Protocol (default)
-     * - ``RTEMS_MULTIPROCESSOR_RESOURCE_SHARING``
-       - use Multiprocessor Resource Sharing Protocol
-     * - ``RTEMS_LOCAL``
-       - local semaphore (default)
-     * - ``RTEMS_GLOBAL``
-       - global semaphore
-
-    Semaphores should not be made global unless remote tasks must interact with
-    the created semaphore.  This is to avoid the system overhead incurred by
-    the creation of a global semaphore.  When a global semaphore is created,
-    the semaphore's name and id must be transmitted to every node in the system
-    for insertion in the local copy of the global object table.
-
-    *Note*, some combinations of attributes are not valid.  See the earlier
-    discussion on this.
-
-    The total number of global objects, including semaphores, is limited by the
-    maximum_global_objects field in the Configuration Table.
-
-    It is not allowed to create an initially locked MrsP semaphore and the
-    ``RTEMS_INVALID_NUMBER`` status code will be returned in SMP configurations
-    in this case.  This prevents lock order reversal problems with the
-    allocator mutex.
-
-.. raw:: latex
-
-   \clearpage
-
-.. index:: get ID of a semaphore
-.. index:: obtain ID of a semaphore
-.. index:: rtems_semaphore_ident
-
-.. _rtems_semaphore_ident:
-
-SEMAPHORE_IDENT - Get ID of a semaphore
----------------------------------------
-
-CALLING SEQUENCE:
-    .. code-block:: c
-
-        rtems_status_code rtems_semaphore_ident(
-            rtems_name  name,
-            uint32_t    node,
-            rtems_id   *id
-        );
-
-DIRECTIVE STATUS CODES:
-    .. list-table::
-     :class: rtems-table
-
-     * - ``RTEMS_SUCCESSFUL``
-       - semaphore identified successfully
-     * - ``RTEMS_INVALID_NAME``
-       - semaphore name not found
-     * - ``RTEMS_INVALID_NODE``
-       - invalid node id
-
-DESCRIPTION:
-    This directive obtains the semaphore id associated with the semaphore name.
-    If the semaphore name is not unique, then the semaphore id will match one
-    of the semaphores with that name.  However, this semaphore id is not
-    guaranteed to correspond to the desired semaphore.  The semaphore id is
-    used by other semaphore related directives to access the semaphore.
-
-NOTES:
-    This directive will not cause the running task to be preempted.
-
-    If node is ``RTEMS_SEARCH_ALL_NODES``, all nodes are searched with the
-    local node being searched first.  All other nodes are searched with the
-    lowest numbered node searched first.
-
-    If node is a valid node number which does not represent the local node,
-    then only the semaphores exported by the designated node are searched.
-
-    This directive does not generate activity on remote nodes.  It accesses
-    only the local copy of the global object table.
-
-.. raw:: latex
-
-   \clearpage
-
-.. index:: delete a semaphore
-.. index:: rtems_semaphore_delete
-
-.. _rtems_semaphore_delete:
-
-SEMAPHORE_DELETE - Delete a semaphore
--------------------------------------
-
-CALLING SEQUENCE:
-    .. code-block:: c
-
-        rtems_status_code rtems_semaphore_delete(
-            rtems_id id
-        );
-
-DIRECTIVE STATUS CODES:
-    .. list-table::
-     :class: rtems-table
-
-     * - ``RTEMS_SUCCESSFUL``
-       - semaphore deleted successfully
-     * - ``RTEMS_INVALID_ID``
-       - invalid semaphore id
-     * - ``RTEMS_RESOURCE_IN_USE``
-       - binary semaphore is in use
-     * - ``RTEMS_ILLEGAL_ON_REMOTE_OBJECT``
-       - cannot delete remote semaphore
-
-DESCRIPTION:
-    This directive deletes the semaphore specified by ``id``.  All tasks
-    blocked waiting to acquire the semaphore will be readied and returned a
-    status code which indicates that the semaphore was deleted.  The SMCB for
-    this semaphore 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 will be preempted if it is enabled by the task's execution
-    mode and a higher priority local task is waiting on the deleted semaphore.
-    The calling task will NOT be preempted if all of the tasks that are waiting
-    on the semaphore are remote tasks.
-
-    The calling task does not have to be the task that created the semaphore.  Any
-    local task that knows the semaphore id can delete the semaphore.
-
-    When a global semaphore is deleted, the semaphore id must be transmitted to
-    every node in the system for deletion from the local copy of the global
-    object table.
-
-    The semaphore must reside on the local node, even if the semaphore was
-    created with the ``RTEMS_GLOBAL`` option.
-
-    Proxies, used to represent remote tasks, are reclaimed when the semaphore
-    is deleted.
-
-.. raw:: latex
-
-   \clearpage
-
-.. index:: obtain a semaphore
-.. index:: lock a semaphore
-.. index:: rtems_semaphore_obtain
-
-.. _rtems_semaphore_obtain:
-
-SEMAPHORE_OBTAIN - Acquire a semaphore
---------------------------------------
-
-CALLING SEQUENCE:
-    .. code-block:: c
-
-        rtems_status_code rtems_semaphore_obtain(
-            rtems_id        id,
-            rtems_option    option_set,
-            rtems_interval  timeout
-        );
-
-DIRECTIVE STATUS CODES:
-    .. list-table::
-     :class: rtems-table
-
-     * - ``RTEMS_SUCCESSFUL``
-       - semaphore obtained successfully
-     * - ``RTEMS_UNSATISFIED``
-       - semaphore not available
-     * - ``RTEMS_TIMEOUT``
-       - timed out waiting for semaphore
-     * - ``RTEMS_OBJECT_WAS_DELETED``
-       - semaphore deleted while waiting
-     * - ``RTEMS_INVALID_ID``
-       - invalid semaphore id
-
-DESCRIPTION:
-    This directive acquires the semaphore specified by id.  The ``RTEMS_WAIT``
-    and ``RTEMS_NO_WAIT`` components of the options parameter indicate whether
-    the calling task wants to wait for the semaphore to become available or
-    return immediately if the semaphore is not currently available.  With
-    either ``RTEMS_WAIT`` or ``RTEMS_NO_WAIT``, if the current semaphore count
-    is positive, then it is decremented by one and the semaphore is
-    successfully acquired by returning immediately with a successful return
-    code.
-
-    If the calling task chooses to return immediately and the current semaphore
-    count is zero or negative, then a status code is returned indicating that
-    the semaphore is not available. If the calling task chooses to wait for a
-    semaphore and the current semaphore count is zero or negative, then it is
-    decremented by one and the calling task is placed on the semaphore's wait
-    queue and blocked.  If the semaphore was created with the
-    ``RTEMS_PRIORITY`` attribute, then the calling task is inserted into the
-    queue according to its priority.  However, if the semaphore was created
-    with the ``RTEMS_FIFO`` attribute, then the calling task is placed at the
-    rear of the wait queue.  If the binary semaphore was created with the
-    ``RTEMS_INHERIT_PRIORITY`` attribute, then the priority of the task
-    currently holding the binary semaphore is guaranteed to be greater than or
-    equal to that of the blocking task.  If the binary semaphore was created
-    with the ``RTEMS_PRIORITY_CEILING`` attribute, a task successfully obtains
-    the semaphore, and the priority of that task is greater than the ceiling
-    priority for this semaphore, then the priority of the task obtaining the
-    semaphore is elevated to that of the ceiling.
-
-    The timeout parameter specifies the maximum interval the calling task is
-    willing to be blocked waiting for the semaphore.  If it is set to
-    ``RTEMS_NO_TIMEOUT``, then the calling task will wait forever.  If the
-    semaphore is available or the ``RTEMS_NO_WAIT`` option component is set,
-    then timeout is ignored.
-
-    In case a semaphore is not available, then ``RTEMS_UNSATISFIED`` will be
-    returned.  This happens immediately in case ``RTEMS_NO_WAIT`` is specified,
-    or as a result of another task invoking the ``rtems_semaphore_flush``
-    directive in case ``RTEMS_WAIT`` is specified.
-
-    Deadlock situations are detected for MrsP semaphores and the
-    ``RTEMS_UNSATISFIED`` status code will be returned in SMP configurations in
-    this case.
-
-NOTES:
-    The following semaphore acquisition option constants are defined by RTEMS:
-
-    .. list-table::
-     :class: rtems-table
-
-     * - ``RTEMS_WAIT``
-       - task will wait for semaphore (default)
-     * - ``RTEMS_NO_WAIT``
-       - task should not wait
-
-    Attempting to obtain a global semaphore which does not reside on the local
-    node will generate a request to the remote node to access the semaphore.
-    If the semaphore is not available and ``RTEMS_NO_WAIT`` was not specified,
-    then the task must be blocked until the semaphore is released.  A proxy is
-    allocated on the remote node to represent the task until the semaphore is
-    released.
-
-    A clock tick is required to support the timeout functionality of this
-    directive.
-
-    It is not allowed to obtain a MrsP semaphore more than once by one task at
-    a time (nested access) and the ``RTEMS_UNSATISFIED`` status code will be
-    returned in SMP configurations in this case.
-
-.. raw:: latex
-
-   \clearpage
-
-.. index:: release a semaphore
-.. index:: unlock a semaphore
-.. index:: rtems_semaphore_release
-
-.. _rtems_semaphore_release:
-
-SEMAPHORE_RELEASE - Release a semaphore
----------------------------------------
-
-CALLING SEQUENCE:
-    .. code-block:: c
-
-        rtems_status_code rtems_semaphore_release(
-            rtems_id id
-        );
-
-DIRECTIVE STATUS CODES:
-    .. list-table::
-     :class: rtems-table
-
-     * - ``RTEMS_SUCCESSFUL``
-       - semaphore released successfully
-     * - ``RTEMS_INVALID_ID``
-       - invalid semaphore id
-     * - ``RTEMS_NOT_OWNER_OF_RESOURCE``
-       - calling task does not own semaphore
-     * - ``RTEMS_INCORRECT_STATE``
-       - invalid unlock order
-
-DESCRIPTION:
-    This directive releases the semaphore specified by id.  The semaphore count
-    is incremented by one.  If the count is zero or negative, then the first
-    task on this semaphore's wait queue is removed and unblocked.  The
-    unblocked task may preempt the running task if the running task's
-    preemption mode is enabled and the unblocked task has a higher priority
-    than the running task.
-
-NOTES:
-    The calling task may be preempted if it causes a higher priority task to be
-    made ready for execution.
-
-    Releasing a global semaphore which does not reside on the local node will
-    generate a request telling the remote node to release the semaphore.
-
-    If the task to be unblocked resides on a different node from the semaphore,
-    then the semaphore allocation is forwarded to the appropriate node, the
-    waiting task is unblocked, and the proxy used to represent the task is
-    reclaimed.
-
-    The outermost release of a local, binary, priority inheritance or priority
-    ceiling semaphore may result in the calling task having its priority
-    lowered.  This will occur if the calling task holds no other binary
-    semaphores and it has inherited a higher priority.
-
-    The MrsP semaphores must be released in the reversed obtain order,
-    otherwise the ``RTEMS_INCORRECT_STATE`` status code will be returned in SMP
-    configurations in this case.
-
-.. raw:: latex
-
-   \clearpage
-
-.. index:: flush a semaphore
-.. index:: unblock all tasks waiting on a semaphore
-.. index:: rtems_semaphore_flush
-
-.. _rtems_semaphore_flush:
-
-SEMAPHORE_FLUSH - Unblock all tasks waiting on a semaphore
-----------------------------------------------------------
-
-CALLING SEQUENCE:
-    .. code-block:: c
-
-        rtems_status_code rtems_semaphore_flush(
-            rtems_id id
-        );
-
-DIRECTIVE STATUS CODES:
-    .. list-table::
-     :class: rtems-table
-
-     * - ``RTEMS_SUCCESSFUL``
-       - semaphore released successfully
-     * - ``RTEMS_INVALID_ID``
-       - invalid semaphore id
-     * - ``RTEMS_NOT_DEFINED``
-       - operation not defined for the protocol of the semaphore
-     * - ``RTEMS_ILLEGAL_ON_REMOTE_OBJECT``
-       - not supported for remote semaphores
-
-DESCRIPTION:
-    This directive unblocks all tasks waiting on the semaphore specified by id.
-    Since there are tasks blocked on the semaphore, the semaphore's count is
-    not changed by this directive and thus is zero before and after this
-    directive is executed.  Tasks which are unblocked as the result of this
-    directive will return from the ``rtems_semaphore_obtain`` directive with a
-    status code of ``RTEMS_UNSATISFIED`` to indicate that the semaphore was not
-    obtained.
-
-    This directive may unblock any number of tasks.  Any of the unblocked tasks
-    may preempt the running task if the running task's preemption mode is
-    enabled and an unblocked task has a higher priority than the running task.
-
-NOTES:
-    The calling task may be preempted if it causes a higher priority task to be
-    made ready for execution.
-
-    If the task to be unblocked resides on a different node from the semaphore,
-    then the waiting task is unblocked, and the proxy used to represent the
-    task is reclaimed.
-
-    It is not allowed to flush a MrsP semaphore and the ``RTEMS_NOT_DEFINED``
-    status code will be returned in SMP configurations in this case.
-
-    Using the ``rtems_semaphore_flush`` directive for condition synchronization
-    in concert with another semaphore may be subject to the lost wake-up
-    problem.  The following attempt to implement a condition variable is
-    broken.
-
-    .. code-block:: c
-
-        #include <rtems.h>
-        #include <assert.h>
-
-        void cnd_wait( rtems_id cnd, rtems_id mtx )
-        {
-          rtems_status_code sc;
-
-          sc = rtems_semaphore_release( mtx );
-          assert( sc == RTEMS_SUCCESSFUL );
-
-          /*
-           * Here, a higher priority task may run and satisfy the condition. We
-           * may never wake up from the next semaphore obtain.
-           */
-
-          sc = rtems_semaphore_obtain( cnd, RTEMS_WAIT, RTEMS_NO_TIMEOUT );
-          assert( sc == RTEMS_UNSATISFIED );
-
-          sc = rtems_semaphore_obtain( mtx, RTEMS_WAIT, RTEMS_NO_TIMEOUT );
-          assert( sc == RTEMS_SUCCESSFUL );
-        }
-
-        void cnd_broadcast( rtems_id cnd )
-        {
-          rtems_status_code sc;
-
-          sc = rtems_semaphore_flush( cnd );
-          assert( sc == RTEMS_SUCCESSFUL );
-        }
-
-    For barrier synchronization, the :ref:`barrier_manager` offers a cleaner
-    alternative to using the `rtems_semaphore_flush` directive.  Unlike POSIX
-    barriers, they have a manual release option.
-
-.. raw:: latex
-
-   \clearpage
-
-.. index:: set priority by scheduler for a semaphore
-.. index:: rtems_semaphore_set_priority
-
-.. _rtems_semaphore_set_priority:
-
-SEMAPHORE_SET_PRIORITY - Set priority by scheduler for a semaphore
-------------------------------------------------------------------
-
-CALLING SEQUENCE:
-    .. code-block:: c
-
-        rtems_status_code rtems_semaphore_set_priority(
-            rtems_id             semaphore_id,
-            rtems_id             scheduler_id,
-            rtems_task_priority  new_priority,
-            rtems_task_priority *old_priority
-        );
-
-DIRECTIVE STATUS CODES:
-    .. list-table::
-     :class: rtems-table
-
-     * - ``RTEMS_SUCCESSFUL``
-       - successful operation
-     * - ``RTEMS_INVALID_ID``
-       - invalid semaphore or scheduler id
-     * - ``RTEMS_INVALID_ADDRESS``
-       - ``old_priority`` is NULL
-     * - ``RTEMS_INVALID_PRIORITY``
-       - invalid new priority value
-     * - ``RTEMS_NOT_DEFINED``
-       - operation not defined for the protocol ofthe semaphore
-     * - ``RTEMS_ILLEGAL_ON_REMOTE_OBJECT``
-       - not supported for remote semaphores
-
-DESCRIPTION:
-    This directive sets the priority value with respect to the specified
-    scheduler of a semaphore.
-
-    The special priority value ``RTEMS_CURRENT_PRIORITY`` can be used to get
-    the current priority value without changing it.
-
-    The interpretation of the priority value depends on the protocol of the
-    semaphore object.
-
-    - The Multiprocessor Resource Sharing Protocol needs a ceiling priority per
-      scheduler instance.  This operation can be used to specify these priority
-      values.
-
-    - For the Priority Ceiling Protocol the ceiling priority is used with this
-      operation.
-
-    - For other protocols this operation is not defined.
-
-EXAMPLE:
-    .. code-block:: c
-        :linenos:
-
-        #include <assert.h>
-        #include <stdlib.h>
-        #include <rtems.h>
-
-        #define SCHED_A rtems_build_name(' ', ' ', ' ', 'A')
-        #define SCHED_B rtems_build_name(' ', ' ', ' ', 'B')
-
-        static void Init(rtems_task_argument arg)
-        {
-            rtems_status_code   sc;
-            rtems_id            semaphore_id;
-            rtems_id            scheduler_a_id;
-            rtems_id            scheduler_b_id;
-            rtems_task_priority prio;
-
-            /* Get the scheduler identifiers */
-            sc = rtems_scheduler_ident(SCHED_A, &scheduler_a_id);
-            assert(sc == RTEMS_SUCCESSFUL);
-            sc = rtems_scheduler_ident(SCHED_B, &scheduler_b_id);
-            assert(sc == RTEMS_SUCCESSFUL);
-
-            /* Create a MrsP semaphore object */
-            sc = rtems_semaphore_create(
-                rtems_build_name('M', 'R', 'S', 'P'),
-                1,
-                RTEMS_MULTIPROCESSOR_RESOURCE_SHARING | RTEMS_BINARY_SEMAPHORE,
-                1,
-                &semaphore_id
-            );
-            assert(sc == RTEMS_SUCCESSFUL);
-
-            /*
-             * The ceiling priority values per scheduler are equal to the value specified
-             * for object creation.
-             */
-            prio = RTEMS_CURRENT_PRIORITY;
-            sc = rtems_semaphore_set_priority(semaphore_id, scheduler_a_id, prio, &prio);
-            assert(sc == RTEMS_SUCCESSFUL);
-            assert(prio == 1);
-
-            /* Check the old value and set a new ceiling priority for scheduler B */
-            prio = 2;
-            sc = rtems_semaphore_set_priority(semaphore_id, scheduler_b_id, prio, &prio);
-            assert(sc == RTEMS_SUCCESSFUL);
-            assert(prio == 1);
-
-            /* Check the ceiling priority values */
-            prio = RTEMS_CURRENT_PRIORITY;
-            sc = rtems_semaphore_set_priority(semaphore_id, scheduler_a_id, prio, &prio);
-            assert(sc == RTEMS_SUCCESSFUL);
-            assert(prio == 1);
-            prio = RTEMS_CURRENT_PRIORITY;
-            sc = rtems_semaphore_set_priority(semaphore_id, scheduler_b_id, prio, &prio);
-            assert(sc == RTEMS_SUCCESSFUL);
-            assert(prio == 2);
-
-            sc = rtems_semaphore_delete(semaphore_id);
-            assert(sc == RTEMS_SUCCESSFUL);
-
-            exit(0);
-        }
-
-        #define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
-        #define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
-        #define CONFIGURE_MAXIMUM_TASKS 1
-        #define CONFIGURE_MAXIMUM_SEMAPHORES 1
-        #define CONFIGURE_MAXIMUM_PROCESSORS 2
-
-        #define CONFIGURE_SCHEDULER_SIMPLE_SMP
-
-        #include <rtems/scheduler.h>
-
-        RTEMS_SCHEDULER_CONTEXT_SIMPLE_SMP(a);
-        RTEMS_SCHEDULER_CONTEXT_SIMPLE_SMP(b);
-
-        #define CONFIGURE_SCHEDULER_TABLE_ENTRIES \
-            RTEMS_SCHEDULER_TABLE_SIMPLE_SMP(a, SCHED_A), \
-            RTEMS_SCHEDULER_TABLE_SIMPLE_SMP(b, SCHED_B)
-
-        #define CONFIGURE_SCHEDULER_ASSIGNMENTS \
-            RTEMS_SCHEDULER_ASSIGN(0, RTEMS_SCHEDULER_ASSIGN_PROCESSOR_MANDATORY), \
-            RTEMS_SCHEDULER_ASSIGN(1, RTEMS_SCHEDULER_ASSIGN_PROCESSOR_MANDATORY)
-
-        #define CONFIGURE_RTEMS_INIT_TASKS_TABLE
-        #define CONFIGURE_INIT
-
-        #include <rtems/confdefs.h>