diff nuc-fw/nucleus/evc.c @ 79:947b1f473960

beginning of nuc-fw
author Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
date Sun, 11 Aug 2013 07:17:25 +0000
parents
children
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nuc-fw/nucleus/evc.c	Sun Aug 11 07:17:25 2013 +0000
@@ -0,0 +1,886 @@
+/*************************************************************************/
+/*                                                                       */
+/*               Copyright Mentor Graphics Corporation 2002              */
+/*                         All Rights Reserved.                          */
+/*                                                                       */
+/* THIS WORK CONTAINS TRADE SECRET AND PROPRIETARY INFORMATION WHICH IS  */
+/* THE PROPERTY OF MENTOR GRAPHICS CORPORATION OR ITS LICENSORS AND IS   */
+/* SUBJECT TO LICENSE TERMS.                                             */
+/*                                                                       */
+/*************************************************************************/
+
+/*************************************************************************/
+/*                                                                       */
+/* FILE NAME                                               VERSION       */
+/*                                                                       */
+/*      evc.c                                          Nucleus PLUS 1.14 */
+/*                                                                       */
+/* COMPONENT                                                             */
+/*                                                                       */
+/*      EV - Event Group Management                                      */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This file contains the core routines for the Event Group         */
+/*      Management component.                                            */
+/*                                                                       */
+/* DATA STRUCTURES                                                       */
+/*                                                                       */
+/*      None                                                             */
+/*                                                                       */
+/* FUNCTIONS                                                             */
+/*                                                                       */
+/*      EVC_Create_Event_Group              Create an event group        */
+/*      EVC_Delete_Event_Group              Delete an event group        */
+/*      EVC_Set_Events                      Set events in a group        */
+/*      EVC_Retrieve_Events                 Retrieve events from a group */
+/*      EVC_Cleanup                         Cleanup on timeout or a      */
+/*                                            terminate condition        */
+/*                                                                       */
+/* DEPENDENCIES                                                          */
+/*                                                                       */
+/*      cs_extr.h                           Common Service functions     */
+/*      tc_extr.h                           Thread Control functions     */
+/*      ev_extr.h                           Event Group functions        */
+/*      hi_extr.h                           History functions            */
+/*                                                                       */
+/* HISTORY                                                               */
+/*                                                                       */
+/*         DATE                    REMARKS                               */
+/*                                                                       */
+/*      03-01-1993      Created initial version 1.0                      */
+/*      04-19-1993      Verified version 1.0                             */
+/*      08-09-1993      Corrected pointer retrieval                      */
+/*                      loop, resulting in version 1.0a                  */
+/*      08-09-1993      Verified version 1.0a                            */
+/*      03-01-1994      Moved non-core functions into                    */
+/*                      supplemental files, changed                      */
+/*                      function interfaces to match                     */
+/*                      those in prototype, added                        */
+/*                      register options, changed                        */
+/*                      protection logic to reduce                       */
+/*                      overhead, resulting in                           */
+/*                      version 1.1                                      */
+/*                                                                       */
+/*      03-18-1994      Verified version 1.1                             */
+/*      04-17-1996      updated to version 1.2                           */
+/*      10-28-1997      Corrected a problem where                        */
+/*                      NU_Set_Events may not resume all                 */
+/*                      waiting tasks. (SPR190) Created                  */
+/*                      version 1.2a.                                    */
+/*      03-24-1998      Released version 1.3                             */
+/*      03-26-1999      Released 1.11m (new release                      */
+/*                        numbering scheme)                              */
+/*      04-17-2002      Released version 1.13m                           */
+/*      11-07-2002      Released version 1.14                            */
+/*************************************************************************/
+#define         NU_SOURCE_FILE
+
+
+#include        "cs_extr.h"                 /* Common service functions  */
+#include        "tc_extr.h"                 /* Thread control functions  */
+#include        "ev_extr.h"                 /* Event Group functions     */
+#include        "hi_extr.h"                 /* History functions         */
+#include        "profiler.h"                /* ProView interface         */
+
+
+/* Define external inner-component global data references.  */
+
+extern CS_NODE         *EVD_Created_Event_Groups_List;
+extern UNSIGNED         EVD_Total_Event_Groups;
+extern TC_PROTECT       EVD_List_Protect;
+
+
+/* Define internal component function prototypes.  */
+
+VOID    EVC_Cleanup(VOID *information);
+
+
+/*************************************************************************/
+/*                                                                       */
+/* FUNCTION                                                              */
+/*                                                                       */
+/*      EVC_Create_Event_Group                                           */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function creates an event group and then places it on the   */
+/*      list of created event groups.                                    */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      Application                                                      */
+/*      EVCE_Create_Event_Group             Error checking shell         */
+/*                                                                       */
+/* CALLS                                                                 */
+/*                                                                       */
+/*      CSC_Place_On_List                   Add node to linked-list      */
+/*      [HIC_Make_History_Entry]            Make entry in history log    */
+/*      [TCT_Check_Stack]                   Stack checking function      */
+/*      TCT_Protect                         Data structure protect       */
+/*      TCT_Unprotect                       Un-protect data structure    */
+/*                                                                       */
+/* INPUTS                                                                */
+/*                                                                       */
+/*      event_group_ptr                     Event Group control block ptr*/
+/*      name                                Event Group name             */
+/*                                                                       */
+/* OUTPUTS                                                               */
+/*                                                                       */
+/*      NU_SUCCESS                                                       */
+/*                                                                       */
+/* HISTORY                                                               */
+/*                                                                       */
+/*         DATE                    REMARKS                               */
+/*                                                                       */
+/*      03-01-1993      Created initial version 1.0                      */
+/*      04-19-1993      Verified version 1.0                             */
+/*      03-01-1994      Changed function interfaces to                   */
+/*                      match those in prototype,                        */
+/*                      added register options,                          */
+/*                      resulting in version 1.1                         */
+/*                                                                       */
+/*      03-18-1994      Verified version 1.1                             */
+/*                                                                       */
+/*************************************************************************/
+STATUS  EVC_Create_Event_Group(NU_EVENT_GROUP *event_group_ptr, CHAR *name)
+{
+
+R1 EV_GCB      *event_group;                /* Event control block ptr   */
+INT             i;                          /* Working index variable    */
+NU_SUPERV_USER_VARIABLES
+
+    /* Switch to supervisor mode */
+    NU_SUPERVISOR_MODE();
+
+    /* Move input event group pointer into internal pointer.  */
+    event_group =  (EV_GCB *) event_group_ptr;
+
+
+#ifdef  NU_ENABLE_STACK_CHECK
+
+    /* Call stack checking function to check for an overflow condition.  */
+    TCT_Check_Stack();
+
+#endif
+
+#ifdef  NU_ENABLE_HISTORY
+
+    /* Make an entry that corresponds to this function in the system history
+       log.  */
+    HIC_Make_History_Entry(NU_CREATE_EVENT_GROUP_ID, (UNSIGNED) event_group,
+                                        (UNSIGNED) name, (UNSIGNED) 0);
+
+#endif
+
+    /* First, clear the event group ID just in case it is an old Event Group
+       Control Block.  */
+    event_group -> ev_id =             0;
+
+    /* Fill in the event group name.  */
+    for (i = 0; i < NU_MAX_NAME; i++)
+        event_group -> ev_name[i] =  name[i];
+
+    /* Clear the flags of the event group.  */
+    event_group -> ev_current_events =  0;
+
+    /* Clear the suspension list pointer.  */
+    event_group -> ev_suspension_list =  NU_NULL;
+
+    /* Clear the number of tasks waiting on the event_group counter.  */
+    event_group -> ev_tasks_waiting =  0;
+
+    /* Initialize link pointers.  */
+    event_group -> ev_created.cs_previous =    NU_NULL;
+    event_group -> ev_created.cs_next =        NU_NULL;
+
+    /* Protect against access to the list of created event_groups.  */
+    TCT_Protect(&EVD_List_Protect);
+
+    /* At this point the event_group is completely built.  The ID can now be
+       set and it can be linked into the created event_group list.  */
+    event_group -> ev_id =  EV_EVENT_ID;
+
+    /* Link the event group into the list of created event groups and
+       increment the total number of event groups in the system.  */
+    CSC_Place_On_List(&EVD_Created_Event_Groups_List,
+                                        &(event_group -> ev_created));
+    EVD_Total_Event_Groups++;
+#ifdef INCLUDE_PROVIEW
+    _RTProf_DumpEventGroup(RT_PROF_CREATE_EVENT_GROUP,event_group, RT_PROF_OK);
+#endif /*INCLUDE_PROVIEW*/
+
+    /* Release protection against access to the list of created event
+       groups.  */
+    TCT_Unprotect();
+
+    /* Return to user mode */
+    NU_USER_MODE();
+
+    /* Return successful completion.  */
+    return(NU_SUCCESS);
+}
+
+
+/*************************************************************************/
+/*                                                                       */
+/* FUNCTION                                                              */
+/*                                                                       */
+/*      EVC_Delete_Event_Group                                           */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function deletes an event group and removes it from the     */
+/*      list of created event groups.  All tasks suspended on the        */
+/*      event group are resumed.  Note that this function does not       */
+/*      free the memory associated with the event group control block.   */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      Application                                                      */
+/*      EVCE_Delete_Event_Group             Error checking shell         */
+/*                                                                       */
+/* CALLS                                                                 */
+/*                                                                       */
+/*      CSC_Remove_From_List                Remove node from list        */
+/*      [HIC_Make_History_Entry]            Make entry in history log    */
+/*      TCC_Resume_Task                     Resume a suspended task      */
+/*      [TCT_Check_Stack]                   Stack checking function      */
+/*      TCT_Control_To_System               Transfer control to system   */
+/*      TCT_Protect                         Protect created list         */
+/*      TCT_Set_Current_Protect             Modify current protection    */
+/*      TCT_System_Protect                  Setup system protection      */
+/*      TCT_System_Unprotect                Release system protection    */
+/*      TCT_Unprotect                       Release protection           */
+/*                                                                       */
+/* INPUTS                                                                */
+/*                                                                       */
+/*      event_group_ptr                     Event Group control block ptr*/
+/*                                                                       */
+/* OUTPUTS                                                               */
+/*                                                                       */
+/*      NU_SUCCESS                                                       */
+/*                                                                       */
+/* HISTORY                                                               */
+/*                                                                       */
+/*         NAME            DATE                    REMARKS               */
+/*                                                                       */
+/*      03-01-1993      Created initial version 1.0                      */
+/*      04-19-1993      Verified version 1.0                             */
+/*      03-01-1994      Changed function interfaces to                   */
+/*                      match those in prototype,                        */
+/*                      added register options, changed                  */
+/*                      protection logic to reduce                       */
+/*                      overhead, resulting in                           */
+/*                      version 1.1                                      */
+/*                                                                       */
+/*      03-18-1994      Verified version 1.1                             */
+/*                                                                       */
+/*************************************************************************/
+STATUS  EVC_Delete_Event_Group(NU_EVENT_GROUP *event_group_ptr)
+{
+
+R1 EV_GCB      *event_group;                /* Event control block ptr   */
+EV_SUSPEND     *suspend_ptr;                /* Suspend block pointer     */
+EV_SUSPEND     *next_ptr;                   /* Next suspend block        */
+STATUS          preempt;                    /* Status for resume call    */
+NU_SUPERV_USER_VARIABLES
+
+    /* Switch to supervisor mode */
+    NU_SUPERVISOR_MODE();
+
+    /* Move input event group pointer into internal pointer.  */
+    event_group =  (EV_GCB *) event_group_ptr;
+
+
+#ifdef  NU_ENABLE_STACK_CHECK
+
+    /* Call stack checking function to check for an overflow condition.  */
+    TCT_Check_Stack();
+
+#endif
+
+#ifdef  NU_ENABLE_HISTORY
+
+    /* Make an entry that corresponds to this function in the system history
+       log.  */
+    HIC_Make_History_Entry(NU_DELETE_EVENT_GROUP_ID, (UNSIGNED) event_group,
+                                        (UNSIGNED) 0, (UNSIGNED) 0);
+
+#endif
+
+    /* Protect against simultaneous access to the event group.  */
+    TCT_System_Protect();
+
+#ifdef INCLUDE_PROVIEW
+    _RTProf_DumpEventGroup(RT_PROF_DELETE_EVENT_GROUP, event_group, RT_PROF_OK);
+#endif /*INCLUDE_PROVIEW*/
+
+    /* Clear the event group ID.  */
+    event_group -> ev_id =  0;
+
+    /* Release protection.  */
+    TCT_Unprotect();
+
+    /* Protect against access to the list of created event groups.  */
+    TCT_Protect(&EVD_List_Protect);
+
+    /* Remove the event_group from the list of created event groups.  */
+    CSC_Remove_From_List(&EVD_Created_Event_Groups_List,
+                                        &(event_group -> ev_created));
+
+    /* Decrement the total number of created event groups.  */
+    EVD_Total_Event_Groups--;
+
+    /* Pickup the suspended task pointer list.  */
+    suspend_ptr =  event_group -> ev_suspension_list;
+
+    /* Walk the chain task(s) currently suspended on the event_group.  */
+    preempt =  0;
+    while (suspend_ptr)
+    {
+
+        /* Protect against system access.  */
+        TCT_System_Protect();
+
+        /* Resume the suspended task.  Insure that the status returned is
+           NU_GROUP_DELETED.  */
+        suspend_ptr -> ev_return_status =  NU_GROUP_DELETED;
+
+        /* Point to the next suspend structure in the link.  */
+        next_ptr =  (EV_SUSPEND *) (suspend_ptr -> ev_suspend_link.cs_next);
+
+        /* Resume the specified task.  */
+        preempt =  preempt |
+            TCC_Resume_Task((NU_TASK *) suspend_ptr -> ev_suspended_task,
+                                                NU_EVENT_SUSPEND);
+
+        /* Determine if the next is the same as the current pointer.  */
+        if (next_ptr == event_group -> ev_suspension_list)
+
+            /* Clear the suspension pointer to signal the end of the list
+               traversal.  */
+            suspend_ptr =  NU_NULL;
+        else
+
+            /* Move the next pointer into the suspend block pointer.  */
+            suspend_ptr =  next_ptr;
+
+        /* Modify current protection.  */
+        TCT_Set_Current_Protect(&EVD_List_Protect);
+
+        /* Clear the system protection.  */
+        TCT_System_Unprotect();
+    }
+
+    /* Determine if preemption needs to occur.  */
+    if (preempt)
+
+        /* Transfer control to system to facilitate preemption.  */
+        TCT_Control_To_System();
+
+    /* Release protection against access to the list of created
+       event groups. */
+    TCT_Unprotect();
+
+    /* Return to user mode */
+    NU_USER_MODE();
+
+    /* Return a successful completion.  */
+    return(NU_SUCCESS);
+}
+
+
+/*************************************************************************/
+/*                                                                       */
+/* FUNCTION                                                              */
+/*                                                                       */
+/*      EVC_Set_Events                                                   */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function sets event flags within the specified event flag   */
+/*      group.  Event flags may be ANDed or ORed against the current     */
+/*      events of the group.  Any task that is suspended on the group    */
+/*      that has its request satisfied is resumed.                       */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      Application                                                      */
+/*      EVCE_Set_Events                     Error checking shell         */
+/*                                                                       */
+/* CALLS                                                                 */
+/*                                                                       */
+/*      CSC_Remove_From_List                Remove from suspend list     */
+/*      [HIC_Make_History_Entry]            Make entry in history log    */
+/*      TCC_Resume_Task                     Resume a suspended task      */
+/*      [TCT_Check_Stack]                   Stack checking function      */
+/*      TCT_Control_To_System               Transfer control to system   */
+/*      TCT_System_Protect                  Protect event group          */
+/*      TCT_Unprotect                       Release protection           */
+/*                                                                       */
+/* INPUTS                                                                */
+/*                                                                       */
+/*      event_group_ptr                     Event Group control block ptr*/
+/*      events                              Event flag setting           */
+/*      operation                           Operation to perform on the  */
+/*                                            event flag group (AND/OR)  */
+/*                                                                       */
+/* OUTPUTS                                                               */
+/*                                                                       */
+/*      NU_SUCCESS                          If service is successful     */
+/*                                                                       */
+/* HISTORY                                                               */
+/*                                                                       */
+/*         DATE                    REMARKS                               */
+/*                                                                       */
+/*      03-01-1993      Created initial version 1.0                      */
+/*      04-19-1993      Verified version 1.0                             */
+/*      03-01-1994      Changed function interfaces to                   */
+/*                      match those in prototype,                        */
+/*                      added register options, changed                  */
+/*                      protection logic to reduce                       */
+/*                      overhead, resulting in                           */
+/*                      version 1.1                                      */
+/*                                                                       */
+/*      03-18-1994      Verified version 1.1                             */
+/*      11-19-1996      Corrected SPR190.                                */
+/*                                                                       */
+/*************************************************************************/
+STATUS  EVC_Set_Events(NU_EVENT_GROUP *event_group_ptr, UNSIGNED events,
+                                                OPTION operation)
+{
+
+R1 EV_GCB      *event_group;                /* Event control block ptr   */
+R2 EV_SUSPEND  *suspend_ptr;                /* Pointer to suspension blk */
+R3 EV_SUSPEND  *next_ptr;                   /* Pointer to next suspend   */
+R4 EV_SUSPEND  *last_ptr;                   /* Last suspension block ptr */
+UNSIGNED        consume;                    /* Event flags to consume    */
+UNSIGNED        compare;                    /* Event comparison variable */
+INT             preempt;                    /* Preemption required flag  */
+NU_SUPERV_USER_VARIABLES
+
+    /* Switch to supervisor mode */
+    NU_SUPERVISOR_MODE();
+
+    /* Move input event group pointer into internal pointer.  */
+    event_group =  (EV_GCB *) event_group_ptr;
+
+
+#ifdef  NU_ENABLE_STACK_CHECK
+
+    /* Call stack checking function to check for an overflow condition.  */
+    TCT_Check_Stack();
+
+#endif
+
+#ifdef  NU_ENABLE_HISTORY
+
+    /* Make an entry that corresponds to this function in the system history
+       log.  */
+    HIC_Make_History_Entry(NU_SET_EVENTS_ID, (UNSIGNED) event_group,
+                                      (UNSIGNED) events, (UNSIGNED) operation);
+
+#endif
+
+    /* Protect against simultaneous access to the event group.  */
+    TCT_System_Protect();
+
+    /* Perform the specified operation on the current event flags in the
+       group.  */
+    if (operation & EV_AND)
+
+        /* AND the specified events with the current events.  */
+        event_group -> ev_current_events =
+                        event_group -> ev_current_events & events;
+    else
+
+        /* OR the specified events with the current events.  */
+        event_group -> ev_current_events =
+                        event_group -> ev_current_events | events;
+
+#ifdef INCLUDE_PROVIEW
+    _RTProf_DumpEventGroup(RT_PROF_SET_EVENTS,event_group , RT_PROF_OK);
+#endif /*INCLUDE_PROVIEW*/
+    /* Determine if there are any tasks suspended for events from this
+       event flag group.  */
+    if (event_group -> ev_suspension_list)
+    {
+
+        /* Initialize the consumption bits to 0.  */
+        consume =  0;
+
+        /* Now, walk the chain of tasks suspended on this event flag group to
+           determine if any of their requests can be satisfied.  */
+        suspend_ptr =  event_group -> ev_suspension_list;
+
+        /* Setup a pointer to the last suspension block.  */
+        last_ptr =  (EV_SUSPEND *) suspend_ptr -> ev_suspend_link.cs_previous;
+
+        /* Clear the preempt flag.  */
+        preempt =  0;
+        do
+        {
+
+            /* Determine if this request has been satisfied.  */
+
+            /* First, find the event flags in common.  */
+            compare =  event_group -> ev_current_events &
+                                        suspend_ptr -> ev_requested_events;
+
+            /* Second, determine if all the event flags must match.  */
+            if (suspend_ptr -> ev_operation & EV_AND)
+
+                /* Yes, an AND condition is present.  All requested events
+                   must be present.  */
+                compare =  (compare == suspend_ptr -> ev_requested_events);
+
+            /* Setup the next pointer.  Note that this must be done before
+               the suspended task is resumed, since its suspend block could
+               get corrupted.  */
+            next_ptr =  (EV_SUSPEND *) suspend_ptr -> ev_suspend_link.cs_next;
+
+            /* If compare is non-zero, the suspended task's event request is
+               satisfied.  */
+            if (compare)
+            {
+
+                /* Decrement the number of tasks waiting counter.  */
+                event_group -> ev_tasks_waiting--;
+
+                /* Determine if consumption is requested.  */
+                if (suspend_ptr -> ev_operation & EV_CONSUME)
+
+                    /* Keep track of the event flags to consume.  */
+                    consume =  consume | suspend_ptr -> ev_requested_events;
+
+                /* Remove the first suspended block from the list.  */
+                CSC_Remove_From_List((CS_NODE **)
+                        &(event_group -> ev_suspension_list),
+                                &(suspend_ptr -> ev_suspend_link));
+
+                /* Setup the appropriate return value.  */
+                suspend_ptr -> ev_return_status =  NU_SUCCESS;
+                suspend_ptr -> ev_actual_events =
+                                        event_group -> ev_current_events;
+
+                /* Resume the suspended task.  */
+                preempt = preempt |
+                 TCC_Resume_Task((NU_TASK *) suspend_ptr -> ev_suspended_task,
+                                                       NU_EVENT_SUSPEND);
+
+            }
+
+            /* Determine if there is another suspension block to examine.  */
+            if (suspend_ptr != last_ptr)
+
+                /* More to examine in the suspension list.  Look at the
+                   next suspend block.  */
+                suspend_ptr =  next_ptr;
+            else
+
+                /* End of the list has been reached.  Set the suspend pointer
+                   to NULL to end the search.  */
+                suspend_ptr =  NU_NULL;
+
+        } while (suspend_ptr);
+
+        /* Apply all of the gathered consumption bits.  */
+        event_group -> ev_current_events =
+           event_group -> ev_current_events & ~consume;
+
+        /* Determine if a preempt condition is present.  */
+        if (preempt)
+
+            /* Transfer control to the system if the resumed task function
+               detects a preemption condition.  */
+            TCT_Control_To_System();
+    }
+
+    /* Release protection of the event_group.  */
+    TCT_Unprotect();
+
+    /* Return to user mode */
+    NU_USER_MODE();
+
+    /* Return a successful status.  */
+    return(NU_SUCCESS);
+}
+
+
+
+/*************************************************************************/
+/*                                                                       */
+/* FUNCTION                                                              */
+/*                                                                       */
+/*      EVC_Retrieve_Events                                              */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function retrieves various combinations of event flags from */
+/*      the specified event group.  If the group does not contain the    */
+/*      necessary flags, suspension of the calling task is possible.     */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      Application                                                      */
+/*      EVCE_Retrieve_Events                Error checking shell         */
+/*                                                                       */
+/* CALLS                                                                 */
+/*                                                                       */
+/*      CSC_Place_On_List                   Place on suspend list        */
+/*      [HIC_Make_History_Entry]            Make entry in history log    */
+/*      TCC_Suspend_Task                    Suspend calling task         */
+/*      [TCT_Check_Stack]                   Stack checking function      */
+/*      TCT_Current_Thread                  Pickup current thread pointer*/
+/*      TCT_System_Protect                  Protect event group          */
+/*      TCT_Unprotect                       Release protection           */
+/*                                                                       */
+/* INPUTS                                                                */
+/*                                                                       */
+/*      event_group_ptr                     Event Group control block ptr*/
+/*      requested_events                    Requested event flags        */
+/*      operation                           AND/OR selection of flags    */
+/*      retrieved_events                    Pointer to destination for   */
+/*                                            actual flags retrieved     */
+/*      suspend                             Suspension option            */
+/*                                                                       */
+/* OUTPUTS                                                               */
+/*                                                                       */
+/*      NU_SUCCESS                          If successful completion     */
+/*      NU_TIMEOUT                          If timeout on suspension     */
+/*      NU_NOT_PRESENT                      If event flags are not       */
+/*                                            present                    */
+/*                                                                       */
+/* HISTORY                                                               */
+/*                                                                       */
+/*         DATE                    REMARKS                               */
+/*                                                                       */
+/*      03-01-1993      Created initial version 1.0                      */
+/*      04-19-1993      Verified version 1.0                             */
+/*      03-01-1994      Changed function interfaces to                   */
+/*                      match those in prototype,                        */
+/*                      added register options, changed                  */
+/*                      protection logic to reduce                       */
+/*                      overhead, resulting in                           */
+/*                      version 1.1                                      */
+/*                                                                       */
+/*      03-18-1994      Verified version 1.1                             */
+/*                                                                       */
+/*************************************************************************/
+STATUS  EVC_Retrieve_Events(NU_EVENT_GROUP *event_group_ptr,
+                        UNSIGNED requested_events, OPTION operation,
+                        UNSIGNED *retrieved_events, UNSIGNED suspend)
+{
+
+R1 EV_GCB      *event_group;                /* Event control block ptr   */
+R2 EV_SUSPEND  *suspend_ptr;                /* Pointer to suspend block  */
+EV_SUSPEND      suspend_block;              /* Suspension block          */
+R3 UNSIGNED     compare;                    /* Event comparison variable */
+TC_TCB         *task;                       /* Pointer to task           */
+STATUS          status;                     /* Completion status         */
+NU_SUPERV_USER_VARIABLES
+
+    /* Switch to supervisor mode */
+    NU_SUPERVISOR_MODE();
+
+    /* Move input event group pointer into internal pointer.  */
+    event_group =  (EV_GCB *) event_group_ptr;
+
+
+#ifdef  NU_ENABLE_STACK_CHECK
+
+    /* Call stack checking function to check for an overflow condition.  */
+    TCT_Check_Stack();
+
+#endif
+
+#ifdef  NU_ENABLE_HISTORY
+
+    /* Make an entry that corresponds to this function in the system history
+       log.  */
+    HIC_Make_History_Entry(NU_RETRIEVE_EVENTS_ID, (UNSIGNED) event_group,
+                            (UNSIGNED) requested_events, (UNSIGNED) operation);
+
+#endif
+
+    /* Initialize the status as successful.  */
+    status =  NU_SUCCESS;
+
+    /* Protect against simultaneous access to the event group.  */
+    TCT_System_Protect();
+
+    /* Determine if the events requested are present.  */
+
+    /* Isolate common event flags.  */
+    compare =  event_group -> ev_current_events & requested_events;
+
+    /* Determine if all of the events must be present.  */
+    if (operation & EV_AND)
+
+        /* Yes, all events must be present.  See if the compare value is
+           the same as the requested value.  */
+        compare =  (compare == requested_events);
+
+    /* Determine if the requested combination of event flags are present.  */
+    if (compare)
+    {
+
+        /* Yes, necessary event flags are present.  */
+
+        /* Copy the current event flags into the appropriate destination.  */
+        *retrieved_events =  event_group -> ev_current_events;
+
+        /* Determine if consumption is required.  If so, consume the event
+           flags present in the group.  */
+        if (operation & EV_CONSUME)
+
+            event_group -> ev_current_events =
+                event_group -> ev_current_events & ~requested_events;
+
+#ifdef INCLUDE_PROVIEW
+        _RTProf_DumpEventGroup(RT_PROF_RETRIEVE_EVENTS,event_group, RT_PROF_OK);
+#endif /*INCLUDE_PROVIEW*/
+
+    }
+    else
+    {
+
+        /* Determine if the task requested suspension.  */
+        if (suspend)
+        {
+
+            /* Suspension is selected.  */
+
+            /* Increment the number of tasks waiting.  */
+            event_group -> ev_tasks_waiting++;
+
+#ifdef INCLUDE_PROVIEW
+            _RTProf_DumpEventGroup(RT_PROF_RETRIEVE_EVENTS,event_group, RT_PROF_WAIT);
+#endif /*INCLUDE_PROVIEW*/
+
+            /* Setup the suspend block and suspend the calling task.  */
+            suspend_ptr =  &suspend_block;
+            suspend_ptr -> ev_event_group =              event_group;
+            suspend_ptr -> ev_suspend_link.cs_next =     NU_NULL;
+            suspend_ptr -> ev_suspend_link.cs_previous = NU_NULL;
+            task =                            (TC_TCB *) TCT_Current_Thread();
+            suspend_ptr -> ev_suspended_task =           task;
+            suspend_ptr -> ev_requested_events =         requested_events;
+            suspend_ptr -> ev_operation =                operation;
+
+            /* Link the suspend block into the list of suspended tasks on this
+               event group.  */
+            CSC_Place_On_List((CS_NODE **)
+                        &(event_group -> ev_suspension_list),
+                                        &(suspend_ptr -> ev_suspend_link));
+
+            /* Finally, suspend the calling task. Note that the suspension call
+               automatically clears the protection on the event group.  */
+            TCC_Suspend_Task((NU_TASK *) task, NU_EVENT_SUSPEND,
+                                        EVC_Cleanup, suspend_ptr, suspend);
+
+            /* Pickup the return status and the actual retrieved events.  */
+            status =             suspend_ptr -> ev_return_status;
+            *retrieved_events =  suspend_ptr -> ev_actual_events;
+        }
+        else
+        {
+
+            /* No suspension requested.  Simply return an error status
+               and zero the retrieved events variable.  */
+            status =             NU_NOT_PRESENT;
+            *retrieved_events =  0;
+#ifdef INCLUDE_PROVIEW
+            _RTProf_DumpEventGroup(RT_PROF_RETRIEVE_EVENTS,event_group,RT_PROF_FAIL);
+#endif /*INCLUDE_PROVIEW*/
+        }
+    }
+
+    /* Release protection of the event_group.  */
+    TCT_Unprotect();
+
+    /* Return to user mode */
+    NU_USER_MODE();
+
+    /* Return the completion status.  */
+    return(status);
+}
+
+
+/*************************************************************************/
+/*                                                                       */
+/* FUNCTION                                                              */
+/*                                                                       */
+/*      EVC_Cleanup                                                      */
+/*                                                                       */
+/* DESCRIPTION                                                           */
+/*                                                                       */
+/*      This function is responsible for removing a suspension block     */
+/*      from a event group.  It is not called unless a timeout or a task */
+/*      terminate is in progress.  Note that protection is already in    */
+/*      effect - the same protection at suspension time.  This routine   */
+/*      must be called from Supervisor mode in Supervisor/User mode      */
+/*      switching kernels.                                               */
+/*                                                                       */
+/* CALLED BY                                                             */
+/*                                                                       */
+/*      TCC_Timeout                         Task timeout                 */
+/*      TCC_Terminate                       Task terminate               */
+/*                                                                       */
+/* CALLS                                                                 */
+/*                                                                       */
+/*      CSC_Remove_From_List                Remove suspend block from    */
+/*                                            the suspension list        */
+/*                                                                       */
+/* INPUTS                                                                */
+/*                                                                       */
+/*      information                         Pointer to suspend block     */
+/*                                                                       */
+/* OUTPUTS                                                               */
+/*                                                                       */
+/*      None                                                             */
+/*                                                                       */
+/* HISTORY                                                               */
+/*                                                                       */
+/*         DATE                    REMARKS                               */
+/*                                                                       */
+/*      03-01-1993      Created initial version 1.0                      */
+/*      04-19-1993      Verified version 1.0                             */
+/*                                                                       */
+/*************************************************************************/
+VOID  EVC_Cleanup(VOID *information)
+{
+
+EV_SUSPEND      *suspend_ptr;               /* Suspension block pointer  */
+NU_SUPERV_USER_VARIABLES
+
+    /* Switch to supervisor mode */
+    NU_SUPERVISOR_MODE();
+
+    /* Use the information pointer as a suspend pointer.  */
+    suspend_ptr =  (EV_SUSPEND *) information;
+
+    /* By default, indicate that the service timed-out.  It really does not
+       matter if this function is called from a terminate request since
+       the task does not resume.  */
+    suspend_ptr -> ev_return_status =  NU_TIMEOUT;
+
+    /* Decrement the number of tasks waiting counter.  */
+    (suspend_ptr -> ev_event_group) -> ev_tasks_waiting--;
+
+    /* Unlink the suspend block from the suspension list.  */
+    CSC_Remove_From_List((CS_NODE **)
+                &((suspend_ptr -> ev_event_group) -> ev_suspension_list),
+                                &(suspend_ptr -> ev_suspend_link));
+
+    /* Return to user mode */
+    NU_USER_MODE();
+}
+
+
+
+
+
+
+