+
−/*************************************************************************/
+
−/*                                                                       */
+
−/*               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       */
+
−/*                                                                       */
+
−/*      smc.c                                          Nucleus PLUS 1.14 */
+
−/*                                                                       */
+
−/* COMPONENT                                                             */
+
−/*                                                                       */
+
−/*      SM - Semaphore Management                                        */
+
−/*                                                                       */
+
−/* DESCRIPTION                                                           */
+
−/*                                                                       */
+
−/*      This file contains the core routines for the Semaphore Management*/
+
−/*      component.                                                       */
+
−/*                                                                       */
+
−/* DATA STRUCTURES                                                       */
+
−/*                                                                       */
+
−/*      None                                                             */
+
−/*                                                                       */
+
−/* FUNCTIONS                                                             */
+
−/*                                                                       */
+
−/*      SMC_Create_Semaphore                Create a semaphore           */
+
−/*      SMC_Delete_Semaphore                Delete a semaphore           */
+
−/*      SMC_Obtain_Semaphore                Obtain instance of semaphore */
+
−/*      SMC_Release_Semaphore               Release instance of semaphore*/
+
−/*      SMC_Cleanup                         Cleanup on timeout or a      */
+
−/*                                            terminate condition        */
+
−/*                                                                       */
+
−/* DEPENDENCIES                                                          */
+
−/*                                                                       */
+
−/*      cs_extr.h                           Common Service functions     */
+
−/*      tc_extr.h                           Thread Control functions     */
+
−/*      sm_extr.h                           Semaphore 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                           */
+
−/*      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        "sm_extr.h"                 /* Semaphore functions       */
+
−#include        "hi_extr.h"                 /* History functions         */
+
−#include        "profiler.h"                /* ProView interface         */
+
−
+
−
+
−/* Define external inner-component global data references.  */
+
−
+
−extern CS_NODE         *SMD_Created_Semaphores_List;
+
−extern UNSIGNED         SMD_Total_Semaphores;
+
−extern TC_PROTECT       SMD_List_Protect;
+
−
+
−
+
−/* Define internal component function prototypes.  */
+
−
+
−VOID    SMC_Cleanup(VOID *information);
+
−
+
−
+
−/*************************************************************************/
+
−/*                                                                       */
+
−/* FUNCTION                                                              */
+
−/*                                                                       */
+
−/*      SMC_Create_Semaphore                                             */
+
−/*                                                                       */
+
−/* DESCRIPTION                                                           */
+
−/*                                                                       */
+
−/*      This function creates a semaphore and then places it on the list */
+
−/*      of created semaphores.                                           */
+
−/*                                                                       */
+
−/* CALLED BY                                                             */
+
−/*                                                                       */
+
−/*      Application                                                      */
+
−/*      SMCE_Create_Semaphore               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                                                                */
+
−/*                                                                       */
+
−/*      semaphore_ptr                       Semaphore control block ptr  */
+
−/*      name                                Semaphore name               */
+
−/*      initial_count                       Initial semaphore instance   */
+
−/*                                            count                      */
+
−/*      suspend_type                        Suspension type              */
+
−/*                                                                       */
+
−/* 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  SMC_Create_Semaphore(NU_SEMAPHORE *semaphore_ptr, CHAR *name,
+
−                           UNSIGNED initial_count, OPTION suspend_type)
+
−{
+
−
+
−R1 SM_SCB      *semaphore;                  /* Semaphore control blk ptr */
+
−INT             i;                          /* Working index variable    */
+
−NU_SUPERV_USER_VARIABLES
+
−
+
−    /* Switch to supervisor mode */
+
−    NU_SUPERVISOR_MODE();
+
−
+
−    /* Move input semaphore pointer into internal pointer.  */
+
−    semaphore =  (SM_SCB *) semaphore_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_SEMAPHORE_ID, (UNSIGNED) semaphore,
+
−                                (UNSIGNED) name, (UNSIGNED) initial_count);
+
−
+
−#endif
+
−
+
−    /* First, clear the semaphore ID just in case it is an old Semaphore
+
−       Control Block.  */
+
−    semaphore -> sm_id =             0;
+
−
+
−    /* Fill in the semaphore name.  */
+
−    for (i = 0; i < NU_MAX_NAME; i++)
+
−        semaphore -> sm_name[i] =  name[i];
+
−
+
−    /* Setup the initial semaphore instance count.  */
+
−    semaphore -> sm_semaphore_count =  initial_count;
+
−
+
−    /* Setup the semaphore suspension type.  */
+
−    if (suspend_type == NU_FIFO)
+
−
+
−        /* FIFO suspension is selected, setup the flag accordingly.  */
+
−        semaphore -> sm_fifo_suspend =  NU_TRUE;
+
−    else
+
−
+
−        /* Priority suspension is selected.  */
+
−        semaphore -> sm_fifo_suspend =  NU_FALSE;
+
−
+
−    /* Clear the suspension list pointer.  */
+
−    semaphore -> sm_suspension_list =  NU_NULL;
+
−
+
−    /* Clear the number of tasks waiting on the semaphore counter.  */
+
−    semaphore -> sm_tasks_waiting =  0;
+
−
+
−    /* Initialize link pointers.  */
+
−    semaphore -> sm_created.cs_previous =    NU_NULL;
+
−    semaphore -> sm_created.cs_next =        NU_NULL;
+
−
+
−    /* Protect against access to the list of created semaphores.  */
+
−    TCT_Protect(&SMD_List_Protect);
+
−
+
−    /* At this point the semaphore is completely built.  The ID can now be
+
−       set and it can be linked into the created semaphore list.  */
+
−    semaphore -> sm_id =  SM_SEMAPHORE_ID;
+
−
+
−    /* Link the semaphore into the list of created semaphores and increment the
+
−       total number of semaphores in the system.  */
+
−    CSC_Place_On_List(&SMD_Created_Semaphores_List,&(semaphore -> sm_created));
+
−    SMD_Total_Semaphores++;
+
−
+
−#ifdef INCLUDE_PROVIEW
+
−    _RTProf_DumpSema(RT_PROF_CREATE_SEMAPHORE,semaphore, RT_PROF_OK);
+
−#endif
+
−
+
−    /* Release protection against access to the list of created semaphores.  */
+
−    TCT_Unprotect();
+
−
+
−    /* Return to user mode */
+
−    NU_USER_MODE();
+
−
+
−    /* Return successful completion.  */
+
−    return(NU_SUCCESS);
+
−}
+
−
+
−
+
−/*************************************************************************/
+
−/*                                                                       */
+
−/* FUNCTION                                                              */
+
−/*                                                                       */
+
−/*      SMC_Delete_Semaphore                                             */
+
−/*                                                                       */
+
−/* DESCRIPTION                                                           */
+
−/*                                                                       */
+
−/*      This function deletes a semaphore and removes it from the list   */
+
−/*      of created semaphores.  All tasks suspended on the semaphore are */
+
−/*      resumed.  Note that this function does not free the memory       */
+
−/*      associated with the semaphore control block.                     */
+
−/*                                                                       */
+
−/* CALLED BY                                                             */
+
−/*                                                                       */
+
−/*      Application                                                      */
+
−/*      SMCE_Delete_Semaphore               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                                                                */
+
−/*                                                                       */
+
−/*      semaphore_ptr                       Semaphore control block ptr  */
+
−/*                                                                       */
+
−/* 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, changed                  */
+
−/*                      protection logic to reduce                       */
+
−/*                      overhead, resulting in                           */
+
−/*                      version 1.1                                      */
+
−/*                                                                       */
+
−/*      03-18-1994      Verified version 1.1                             */
+
−/*                                                                       */
+
−/*************************************************************************/
+
−STATUS  SMC_Delete_Semaphore(NU_SEMAPHORE *semaphore_ptr)
+
−{
+
−
+
−R1 SM_SCB      *semaphore;                  /* Semaphore control blk ptr */
+
−SM_SUSPEND     *suspend_ptr;                /* Suspend block pointer     */
+
−SM_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 semaphore pointer into internal pointer.  */
+
−    semaphore =  (SM_SCB *) semaphore_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_SEMAPHORE_ID, (UNSIGNED) semaphore,
+
−                                        (UNSIGNED) 0, (UNSIGNED) 0);
+
−
+
−#endif
+
−
+
−    /* Protect against access to the semaphore.  */
+
−    TCT_System_Protect();
+
−
+
−#ifdef INCLUDE_PROVIEW
+
−    _RTProf_DumpSema(RT_PROF_DELETE_SEMAPHORE,semaphore, RT_PROF_OK);
+
−#endif
+
−
+
−    /* Clear the semaphore ID.  */
+
−    semaphore -> sm_id =  0;
+
−
+
−    /* Release protection.  */
+
−    TCT_Unprotect();
+
−
+
−    /* Protect against access to the list of created semaphores.  */
+
−    TCT_Protect(&SMD_List_Protect);
+
−
+
−    /* Remove the semaphore from the list of created semaphores.  */
+
−    CSC_Remove_From_List(&SMD_Created_Semaphores_List,
+
−                                        &(semaphore -> sm_created));
+
−
+
−    /* Decrement the total number of created semaphores.  */
+
−    SMD_Total_Semaphores--;
+
−
+
−    /* Pickup the suspended task pointer list.  */
+
−    suspend_ptr =  semaphore -> sm_suspension_list;
+
−
+
−    /* Walk the chain task(s) currently suspended on the semaphore.  */
+
−    preempt =  0;
+
−    while (suspend_ptr)
+
−    {
+
−
+
−        /* Protect against system access.  */
+
−        TCT_System_Protect();
+
−
+
−        /* Resume the suspended task.  Insure that the status returned is
+
−           NU_SEMAPHORE_DELETED.  */
+
−        suspend_ptr -> sm_return_status =  NU_SEMAPHORE_DELETED;
+
−
+
−        /* Point to the next suspend structure in the link.  */
+
−        next_ptr =  (SM_SUSPEND *) (suspend_ptr -> sm_suspend_link.cs_next);
+
−
+
−        /* Resume the specified task.  */
+
−        preempt =  preempt |
+
−            TCC_Resume_Task((NU_TASK *) suspend_ptr -> sm_suspended_task,
+
−                                                NU_SEMAPHORE_SUSPEND);
+
−
+
−        /* Determine if the next is the same as the current pointer.  */
+
−        if (next_ptr == semaphore -> sm_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(&SMD_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 semaphores. */
+
−    TCT_Unprotect();
+
−
+
−    /* Return to user mode */
+
−    NU_USER_MODE();
+
−
+
−    /* Return a successful completion.  */
+
−    return(NU_SUCCESS);
+
−}
+
−
+
−
+
−/*************************************************************************/
+
−/*                                                                       */
+
−/* FUNCTION                                                              */
+
−/*                                                                       */
+
−/*      SMC_Obtain_Semaphore                                             */
+
−/*                                                                       */
+
−/* DESCRIPTION                                                           */
+
−/*                                                                       */
+
−/*      This function obtains an instance of the semaphore.  An instance */
+
−/*      corresponds to decrementing the counter by 1.  If the counter is */
+
−/*      greater than zero at the time of this call, this function can be */
+
−/*      completed immediately.  Otherwise, suspension is possible.       */
+
−/*                                                                       */
+
−/* CALLED BY                                                             */
+
−/*                                                                       */
+
−/*      Application                                                      */
+
−/*      SMCE_Obtain_Semaphore               Error checking shell         */
+
−/*                                                                       */
+
−/* CALLS                                                                 */
+
−/*                                                                       */
+
−/*      CSC_Place_On_List                   Place on suspend list        */
+
−/*      CSC_Priority_Place_On_List          Place on priority list       */
+
−/*      [HIC_Make_History_Entry]            Make entry in history log    */
+
−/*      TCC_Suspend_Task                    Suspend calling task         */
+
−/*      TCC_Task_Priority                   Obtain task's priority       */
+
−/*      [TCT_Check_Stack]                   Stack checking function      */
+
−/*      TCT_Current_Thread                  Pickup current thread pointer*/
+
−/*      TCT_System_Protect                  Protect semaphore            */
+
−/*      TCT_Unprotect                       Release protection           */
+
−/*                                                                       */
+
−/* INPUTS                                                                */
+
−/*                                                                       */
+
−/*      semaphore_ptr                       Semaphore control block ptr  */
+
−/*      suspend                             Suspension option if full    */
+
−/*                                                                       */
+
−/* OUTPUTS                                                               */
+
−/*                                                                       */
+
−/*      NU_SUCCESS                          If service is successful     */
+
−/*      NU_UNAVAILABLE                      If an instance of the        */
+
−/*                                            semaphore is not available */
+
−/*      NU_TIMEOUT                          If timeout on service        */
+
−/*      NU_SEMAPHORE_DELETED                If semaphore deleted during  */
+
−/*                                            suspension                 */
+
−/*      NU_SEMAPHORE_RESET                  If semaphore reset during    */
+
−/*                                            suspension                 */
+
−/*                                                                       */
+
−/* 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  SMC_Obtain_Semaphore(NU_SEMAPHORE *semaphore_ptr,  UNSIGNED suspend)
+
−{
+
−
+
−R1 SM_SCB      *semaphore;                  /* Semaphore control blk ptr */
+
−R2 SM_SUSPEND  *suspend_ptr;                /* Suspend block pointer     */
+
−SM_SUSPEND      suspend_block;              /* Allocate suspension block */
+
−TC_TCB         *task;                       /* Task pointer              */
+
−STATUS          status;                     /* Completion status         */
+
−NU_SUPERV_USER_VARIABLES
+
−
+
−    /* Switch to supervisor mode */
+
−    NU_SUPERVISOR_MODE();
+
−
+
−    /* Move input semaphore pointer into internal pointer.  */
+
−    semaphore =  (SM_SCB *) semaphore_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_OBTAIN_SEMAPHORE_ID, (UNSIGNED) semaphore,
+
−                                        (UNSIGNED) suspend, (UNSIGNED) 0);
+
−
+
−#endif
+
−
+
−    /* Initialize the status as successful.  */
+
−    status =  NU_SUCCESS;
+
−
+
−    /* Protect against simultaneous access to the semaphore.  */
+
−    TCT_System_Protect();
+
−
+
−    /* Determine if the semaphore has an instance (can be decremented).  */
+
−    if (semaphore -> sm_semaphore_count)
+
−    {
+
−
+
−        /* Semaphore available.  Decrement and return to the caller.  */
+
−        semaphore -> sm_semaphore_count--;
+
−#ifdef INCLUDE_PROVIEW
+
−        _RTProf_DumpSema(RT_PROF_OBTAIN_SEMAPHORE,semaphore, RT_PROF_OK);
+
−#endif
+
−
+
−    }
+
−    else
+
−    {
+
−
+
−        /* Semaphore is not available.  Determine if suspension is required. */
+
−        if (suspend)
+
−        {
+
−
+
−            /* Suspension is selected.  */
+
−
+
−            /* Increment the number of tasks waiting.  */
+
−            semaphore -> sm_tasks_waiting++;
+
−
+
−#ifdef INCLUDE_PROVIEW
+
−            _RTProf_DumpSema(RT_PROF_OBTAIN_SEMAPHORE,semaphore , RT_PROF_WAIT);
+
−#endif
+
−
+
−            /* Setup the suspend block and suspend the calling task.  */
+
−            suspend_ptr =  &suspend_block;
+
−            suspend_ptr -> sm_semaphore =                semaphore;
+
−            suspend_ptr -> sm_suspend_link.cs_next =     NU_NULL;
+
−            suspend_ptr -> sm_suspend_link.cs_previous = NU_NULL;
+
−            task =                            (TC_TCB *) TCT_Current_Thread();
+
−            suspend_ptr -> sm_suspended_task =           task;
+
−
+
−            /* Determine if priority or FIFO suspension is associated with the
+
−               semaphore.  */
+
−            if (semaphore -> sm_fifo_suspend)
+
−            {
+
−
+
−                /* FIFO suspension is required.  Link the suspend block into
+
−                   the list of suspended tasks on this semaphore.  */
+
−                CSC_Place_On_List((CS_NODE **)
+
−                        &(semaphore -> sm_suspension_list),
+
−                                        &(suspend_ptr -> sm_suspend_link));
+
−            }
+
−            else
+
−            {
+
−
+
−                /* Get the priority of the current thread so the suspend block
+
−                   can be placed in the appropriate place.  */
+
−                suspend_ptr -> sm_suspend_link.cs_priority =
+
−                                                    TCC_Task_Priority(task);
+
−
+
−                CSC_Priority_Place_On_List((CS_NODE **)
+
−                        &(semaphore -> sm_suspension_list),
+
−                                        &(suspend_ptr -> sm_suspend_link));
+
−            }
+
−
+
−            /* Finally, suspend the calling task. Note that the suspension call
+
−               automatically clears the protection on the semaphore.  */
+
−            TCC_Suspend_Task((NU_TASK *) task, NU_SEMAPHORE_SUSPEND,
+
−                                        SMC_Cleanup, suspend_ptr, suspend);
+
−
+
−            /* Pickup the return status.  */
+
−            status =  suspend_ptr -> sm_return_status;
+
−        }
+
−        else
+
−        {
+
−            /* No suspension requested.  Simply return an error status.  */
+
−            status =  NU_UNAVAILABLE;
+
−
+
−#ifdef INCLUDE_PROVIEW
+
−            _RTProf_DumpSema(RT_PROF_OBTAIN_SEMAPHORE, semaphore,RT_PROF_FAIL);
+
−#endif
+
−        }
+
−    }
+
−
+
−    /* Release protection against access to the semaphore.  */
+
−    TCT_Unprotect();
+
−
+
−    /* Return to user mode */
+
−    NU_USER_MODE();
+
−
+
−    /* Return the completion status.  */
+
−    return(status);
+
−}
+
−
+
−
+
−/*************************************************************************/
+
−/*                                                                       */
+
−/* FUNCTION                                                              */
+
−/*                                                                       */
+
−/*      SMC_Release_Semaphore                                            */
+
−/*                                                                       */
+
−/* DESCRIPTION                                                           */
+
−/*                                                                       */
+
−/*      This function releases a previously obtained semaphore.  If one  */
+
−/*      or more tasks are waiting, the first task is given the released  */
+
−/*      instance of the semaphore.  Otherwise, the semaphore instance    */
+
−/*      counter is simply incremented.                                   */
+
−/*                                                                       */
+
−/* CALLED BY                                                             */
+
−/*                                                                       */
+
−/*      Application                                                      */
+
−/*      SMCE_Release_Semaphore              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 semaphore            */
+
−/*      TCT_Unprotect                       Release protection           */
+
−/*                                                                       */
+
−/* INPUTS                                                                */
+
−/*                                                                       */
+
−/*      semaphore_ptr                       Semaphore control block ptr  */
+
−/*                                                                       */
+
−/* 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, changed                  */
+
−/*                      protection logic to reduce                       */
+
−/*                      overhead, resulting in                           */
+
−/*                      version 1.1                                      */
+
−/*                                                                       */
+
−/*      03-18-1994      Verified version 1.1                             */
+
−/*                                                                       */
+
−/*************************************************************************/
+
−STATUS  SMC_Release_Semaphore(NU_SEMAPHORE *semaphore_ptr)
+
−{
+
−
+
−R1 SM_SCB      *semaphore;                  /* Semaphore control blk ptr */
+
−R2 SM_SUSPEND  *suspend_ptr;                /* Pointer to suspend block  */
+
−STATUS          preempt;                    /* Preemption flag           */
+
−STATUS          status;                     /* Completion status         */
+
−NU_SUPERV_USER_VARIABLES
+
−
+
−    /* Switch to supervisor mode */
+
−    NU_SUPERVISOR_MODE();
+
−
+
−    /* Move input semaphore pointer into internal pointer.  */
+
−    semaphore =  (SM_SCB *) semaphore_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_RELEASE_SEMAPHORE_ID, (UNSIGNED) semaphore,
+
−                                        (UNSIGNED) 0, (UNSIGNED) 0);
+
−
+
−#endif
+
−
+
−    /* Initialize the status as successful.  */
+
−    status =  NU_SUCCESS;
+
−
+
−    /* Protect against simultaneous access to the semaphore.  */
+
−    TCT_System_Protect();
+
−
+
−    /* Determine if another task is waiting on the semaphore.  */
+
−    if (semaphore -> sm_tasks_waiting)
+
−    {
+
−
+
−        /* Yes, another task is waiting for an instance of the semaphore.  */
+
−
+
−        /* Decrement the number of tasks waiting counter.  */
+
−        semaphore -> sm_tasks_waiting--;
+
−
+
−#ifdef INCLUDE_PROVIEW
+
−        _RTProf_DumpSema(RT_PROF_RELEASE_SEMAPHORE, semaphore,RT_PROF_OK);
+
−#endif
+
−
+
−        /* Remove the first suspended block from the list.  */
+
−        suspend_ptr =  semaphore -> sm_suspension_list;
+
−        CSC_Remove_From_List((CS_NODE **) &(semaphore -> sm_suspension_list),
+
−                                &(suspend_ptr -> sm_suspend_link));
+
−
+
−        /* Setup the appropriate return value.  */
+
−        suspend_ptr -> sm_return_status =  NU_SUCCESS;
+
−
+
−        /* Resume the suspended task.  */
+
−        preempt =
+
−            TCC_Resume_Task((NU_TASK *) suspend_ptr -> sm_suspended_task,
+
−                                                       NU_SEMAPHORE_SUSPEND);
+
−
+
−        /* 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();
+
−    }
+
−    else
+
−    {
+
−
+
−        /* Increment the semaphore instance counter.  */
+
−        semaphore -> sm_semaphore_count++;
+
−
+
−#ifdef INCLUDE_PROVIEW
+
−        _RTProf_DumpSema(RT_PROF_RELEASE_SEMAPHORE, semaphore,RT_PROF_OK);
+
−#endif
+
−    }
+
−
+
−    /* Release protection against access to the semaphore.  */
+
−    TCT_Unprotect();
+
−
+
−    /* Return to user mode */
+
−    NU_USER_MODE();
+
−
+
−    /* Return the completion status.  */
+
−    return(status);
+
−}
+
−
+
−
+
−/*************************************************************************/
+
−/*                                                                       */
+
−/* FUNCTION                                                              */
+
−/*                                                                       */
+
−/*      SMC_Cleanup                                                      */
+
−/*                                                                       */
+
−/* DESCRIPTION                                                           */
+
−/*                                                                       */
+
−/*      This function is responsible for removing a suspension block     */
+
−/*      from a semaphore.  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  SMC_Cleanup(VOID *information)
+
−{
+
−
+
−SM_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 =  (SM_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 -> sm_return_status =  NU_TIMEOUT;
+
−
+
−    /* Decrement the number of tasks waiting counter.  */
+
−    (suspend_ptr -> sm_semaphore) -> sm_tasks_waiting--;
+
−
+
−    /* Unlink the suspend block from the suspension list.  */
+
−    CSC_Remove_From_List((CS_NODE **)
+
−                &((suspend_ptr -> sm_semaphore) -> sm_suspension_list),
+
−                                &(suspend_ptr -> sm_suspend_link));
+
−
+
−    /* Return to user mode */
+
−    NU_USER_MODE();
+
−}
+
−
+
−
+
−
+
−
+
−
+
−