pic.c

nucleus 2006 source code

#endif

#ifdef  NU_ENABLE_HISTORY

    /* Make an entry that corresponds to this function in the system history
       log.  */
    HIC_Make_History_Entry(NU_DELETE_PIPE_ID, (UNSIGNED) pipe,
                                        (UNSIGNED) 0, (UNSIGNED) 0);

#endif

    /* Protect against access to the pipe.  */
    TCT_System_Protect();

#ifdef NU_PROFILE_PLUS

    PRF_PLUS_PIC_DELETE_PIPE_0

#endif /* NU_PROFILE_PLUS */

    /* Clear the pipe ID.  */
    pipe -> pi_id =  0;

    /* Release protection.  */
    TCT_Unprotect();

    /* Protect against access to the list of created pipes.  */
    TCT_Protect(&PID_List_Protect);

    /* Remove the pipe from the list of created pipes.  */
    CSC_Remove_From_List(&PID_Created_Pipes_List, &(pipe -> pi_created));

    /* Decrement the total number of created pipes.  */
    PID_Total_Pipes--;

    /* Pickup the suspended task pointer list.  */
    suspend_ptr =  pipe -> pi_suspension_list;

    /* Walk the chain task(s) currently suspended on the pipe.  */
    preempt =  0;
    while (suspend_ptr)
    {

        /* Protect against system access.  */
        TCT_System_Protect();

        /* Resume the suspended task.  Insure that the status returned is
           NU_PIPE_DELETED.  */
        suspend_ptr -> pi_return_status =  NU_PIPE_DELETED;

        /* Point to the next suspend structure in the link.  */
        next_ptr =  (PI_SUSPEND *) (suspend_ptr -> pi_suspend_link.cs_next);

        /* Resume the specified task.  */
        preempt =  preempt |
            TCC_Resume_Task((NU_TASK *) suspend_ptr -> pi_suspended_task,
                                                        NU_PIPE_SUSPEND);

        /* Determine if the next is the same as the head pointer.  */
        if (next_ptr == pipe -> pi_suspension_list)

            /* Clear the suspension pointer to signal the end of the list
               traversal.  */
            suspend_ptr =  NU_NULL;
        else

            /* Setup the next suspension pointer.  */
            suspend_ptr =  next_ptr;

        /* Modify current protection.  */
        TCT_Set_Current_Protect(&PID_List_Protect);

        /* Clear the system protection.  */
        TCT_System_Unprotect();
    }

    /* Pickup the urgent message suspension list.  */
    suspend_ptr =  pipe -> pi_urgent_list;

    /* Walk the chain task(s) currently suspended on the pipe.  */
    while (suspend_ptr)
    {

        /* Protect against system access.  */
        TCT_System_Protect();

        /* Resume the suspended task.  Insure that the status returned is
           NU_PIPE_DELETED.  */
        suspend_ptr -> pi_return_status =  NU_PIPE_DELETED;

        /* Point to the next suspend structure in the link.  */
        next_ptr =  (PI_SUSPEND *) (suspend_ptr -> pi_suspend_link.cs_next);

        /* Resume the specified task.  */
        preempt =  preempt |
            TCC_Resume_Task((NU_TASK *) suspend_ptr -> pi_suspended_task,
                                                        NU_PIPE_SUSPEND);

        /* Determine if the next is the same as the head pointer.  */
        if (next_ptr == pipe -> pi_urgent_list)

            /* Clear the suspension pointer to signal the end of the list
               traversal.  */
            suspend_ptr =  NU_NULL;
        else

            /* Position suspend pointer to the next block.  */
            suspend_ptr =  next_ptr;

        /* Modify current protection.  */
        TCT_Set_Current_Protect(&PID_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 pipes.  */
    TCT_Unprotect();

    /* Return to user mode */
    NU_USER_MODE();

    /* Return a successful completion.  */
    return(NU_SUCCESS);
}


/*************************************************************************/
/*                                                                       */
/* FUNCTION                                                              */
/*                                                                       */
/*      PIC_Send_To_Pipe                                                 */
/*                                                                       */
/* DESCRIPTION                                                           */
/*                                                                       */
/*      This function sends a message to the specified pipe.  The        */
/*      message length is determined by the caller.  If there are one    */
/*      or more tasks suspended on the pipe for a message, the message   */
/*      is copied into the message area of the first waiting task.  If   */
/*      the task's request is satisfied, it is resumed.  Otherwise, if   */
/*      the pipe cannot hold the message, suspension of the calling      */
/*      task is an option of the caller.                                 */
/*                                                                       */
/* CALLED BY                                                             */
/*                                                                       */
/*      Application                                                      */
/*      PICE_Send_To_Pipe                   Error checking shell         */
/*                                                                       */
/* CALLS                                                                 */
/*                                                                       */
/*      CSC_Place_On_List                   Place on suspend list        */
/*      CSC_Priority_Place_On_List          Place on priority list       */
/*      CSC_Remove_From_List                Remove from suspend list     */
/*      [HIC_Make_History_Entry]            Make entry in history log    */
/*      TCC_Resume_Task                     Resume a suspended task      */
/*      TCC_Suspend_Task                    Suspend calling task         */
/*      TCC_Task_Priority                   Pickup task's priority       */
/*      [TCT_Check_Stack]                   Stack checking function      */
/*      TCT_Control_To_System               Transfer control to system   */
/*      TCT_Current_Thread                  Pickup current thread pointer*/
/*      TCT_System_Protect                  Protect pipe                 */
/*      TCT_Unprotect                       Release protection           */
/*                                                                       */
/* INPUTS                                                                */
/*                                                                       */
/*      pipe_ptr                            Pipe control block pointer   */
/*      message                             Pointer to message to send   */
/*      size                                Size of message to send      */
/*      suspend                             Suspension option if full    */
/*                                                                       */
/* OUTPUTS                                                               */
/*                                                                       */
/*      NU_SUCCESS                          If service is successful     */
/*      NU_PIPE_FULL                        If pipe is currently full    */
/*      NU_TIMEOUT                          If timeout on service expires*/
/*      NU_PIPE_DELETED                     If pipe was deleted during   */
/*                                            suspension                 */
/*      NU_PIPE_RESET                       If pipe was reset during     */
/*                                            suspension                 */
/*                                                                       */
/*************************************************************************/
STATUS  PIC_Send_To_Pipe(NU_PIPE *pipe_ptr, VOID *message, UNSIGNED size,
                                                        UNSIGNED suspend)
{

R1 PI_PCB      *pipe;                       /* Pipe control block ptr    */
PI_SUSPEND      suspend_block;              /* Allocate suspension block */
PI_SUSPEND     *suspend_ptr;                /* Pointer to suspend block  */
R2 BYTE_PTR     source;                     /* Pointer to source         */
R3 BYTE_PTR     destination;                /* Pointer to destination    */
UNSIGNED        copy_size;                  /* Partial copy size         */
R4 INT          i;                          /* Working counter           */
UNSIGNED        pad =  0;                   /* Number of pad bytes       */
TC_TCB         *task;                       /* Task pointer              */
STATUS          preempt;                    /* Preempt flag              */
STATUS          status;                     /* Completion status         */
NU_SUPERV_USER_VARIABLES

    /* Switch to supervisor mode */
    NU_SUPERVISOR_MODE();

    /* Move input pipe pointer into internal pointer.  */
    pipe =  (PI_PCB *) pipe_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_SEND_TO_PIPE_ID, (UNSIGNED) pipe,
                                        (UNSIGNED) message, (UNSIGNED) size);

#endif

    /* Initialize the status as successful.  */
    status =  NU_SUCCESS;

    /* Protect against simultaneous access to the pipe.  */
    TCT_System_Protect();

    /* Determine if an extra word of overhead needs to be added to the
       calculation.  */
    if (pipe -> pi_fixed_size)

        /* No overhead.  */
        i =  0;
    else
    {

        /* Variable messages have one additional word of overhead.  */
        i =  sizeof(UNSIGNED);

        /* Calculate the number of pad bytes necessary to make keep the pipe
           write pointer on an UNSIGNED data element alignment.  */
        pad =  (((size + sizeof(UNSIGNED) - 1)/sizeof(UNSIGNED)) *
                            sizeof(UNSIGNED)) - size;

        /* Insure that padding is included in the overhead.  */
        i =  i + ((INT) pad);

        /* Make special check to see if a suspension needs to be
           forced for a variable length message.  */
        if ((pipe -> pi_suspension_list) && (pipe -> pi_messages))
        {

            /* Pickup task control block pointer.  */
            task =  (TC_TCB *) TCT_Current_Thread();

            /* Now we know that there are other task(s) are suspended trying
               to send a variable length message.  Determine whether or not
               a suspension should be forced.  */
            if ((pipe -> pi_fifo_suspend) ||
                (suspend == NU_NO_SUSPEND) ||
                ((pipe -> pi_suspension_list) -> pi_suspend_link.cs_priority <=
                                                    TCC_Task_Priority(task)))

                /* Bump the computed size to avoid placing the new variable
                   length message ahead of the suspended tasks.  */
                i =  (INT) pipe -> pi_available;
        }
    }

    /* Determine if there is enough room in the pipe for the message.  */
    if (pipe -> pi_available < (size + i))
    {

        /* pipe does not have room for the message.  Determine if
           suspension is required.  */
        if (suspend)
        {

            /* Suspension is requested.   */

            /* Increment the number of tasks waiting.  */
            pipe -> pi_tasks_waiting++;

#ifdef NU_PROFILE_PLUS

            PRF_PLUS_PIC_SEND_TO_PIPE_0

#endif /* NU_PROFILE_PLUS */

            /* Setup the suspend block and suspend the calling task.  */
            suspend_ptr =  &suspend_block;
            suspend_ptr -> pi_pipe =                    pipe;
            suspend_ptr -> pi_suspend_link.cs_next =    NU_NULL;
            suspend_ptr -> pi_suspend_link.cs_previous= NU_NULL;
            suspend_ptr -> pi_message_area =            (BYTE_PTR) message;
            suspend_ptr -> pi_message_size =            size;
            task =                           (TC_TCB *) TCT_Current_Thread();
            suspend_ptr -> pi_suspended_task =          task;