view src/nucleus/smc.c @ 214:adfdbcd360fd

backlight evolution: API between Condat driver and MFW With this change, the API between the Condat backlight driver and its user in MFW now carries more abstract backlight state codes (fully off, fully on, in call, charging boot mode) instead of 0-255 levels. This change is needed in order to more properly support different hardware targets with different capabilities and approaches in terms of backlight handling.
author Mychaela Falconia <falcon@freecalypso.org>
date Fri, 23 Apr 2021 23:52:02 +0000
parents 4e78acac3d88
children
line wrap: on
line source

/*************************************************************************/
/*                                                                       */
/*               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();
}