Document rtems_task_get_priority()

Close #2784.

c-user/task_manager.rst

@@ -35,6 +35,8 @@ and administer tasks.  The directives provided by the task manager are:
 
 - rtems_task_set_priority_ - Set task priority
 
+- rtems_task_get_priority_ - Get task priority
+
 - rtems_task_mode_ - Change current task's mode
 
 - rtems_task_wake_after_ - Wake up after interval
@@ -1124,6 +1126,55 @@ NOTES:
 
    \clearpage
 
+.. _rtems_task_get_priority:
+
+TASK_SET_PRIORITY - Get task priority
+-------------------------------------
+.. index:: rtems_task_get_priority
+.. index:: current task priority
+.. index:: get task priority
+.. index:: obtain task priority
+
+CALLING SEQUENCE:
+    .. code-block:: c
+
+        rtems_status_code rtems_task_get_priority(
+            rtems_id             task_id,
+            rtems_id             scheduler_id,
+            rtems_task_priority *priority
+        );
+
+DIRECTIVE STATUS CODES:
+    .. list-table::
+      :class: rtems-table
+
+      * - ``RTEMS_SUCCESSFUL``
+        - Successful operation.
+      * - ``RTEMS_ILLEGAL_ON_REMOTE_OBJECT``
+        - Directive is illegal on remote tasks.
+      * - ``RTEMS_INVALID_ADDRESS``
+        - The priority parameter is NULL.
+      * - ``RTEMS_INVALID_ID``
+        - Invalid task or scheduler identifier.
+      * - ``RTEMS_NOT_DEFINED``
+        - The task has no priority within the specified scheduler instance.
+          This error is only possible in SMP configurations.
+
+DESCRIPTION:
+    This directive returns the current priority of the task specified by
+    :c:data:`task_id` with respect to the scheduler instance specified by
+    :c:data:`scheduler_id`.  A task id of :c:macro:`RTEMS_SELF` is used to
+    indicate the calling task.
+
+NOTES:
+    The current priority reflects temporary priority adjustments due to locking
+    protocols, the rate-monotonic period objects on some schedulers and other
+    mechanisms.
+
+.. raw:: latex
+
+   \clearpage
+
 .. _rtems_task_mode:
 
 TASK_MODE - Change the current task mode