smc.c

test file nucleus source

/*                                                                       */
/* 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)
            {