csc.c

已移植到TI OMAP1610处理器的Nucleus操作系统源码

/*                                                                       */
/*      head                                Pointer to head pointer      */
/*      node                                Pointer to node to add       */
/*                                                                       */
/* OUTPUTS                                                               */
/*                                                                       */
/*      modified list                                                    */
/*                                                                       */
/* HISTORY                                                               */
/*                                                                       */
/*         NAME            DATE                    REMARKS               */
/*                                                                       */
/*      W. Lamie        03-01-1993      Created initial version 1.0      */
/*      D. Lamie        04-19-1993      Verified version 1.0             */
/*                                                                       */
/*************************************************************************/

VOID    CSC_Priority_Place_On_List(CS_NODE **head, CS_NODE *new_node)
{

CS_NODE         *search_ptr;                /* List search pointer       */
NU_SUPERV_USER_VARIABLES

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

    /* Determine if the list in non-empty.  */
    if (*head)
    {

        /* Search the list to find the proper place for the new node.  */
        search_ptr =  (*head);

        /* Check for insertion before the first node on the list.  */
        if (search_ptr -> cs_priority > new_node -> cs_priority)
        {

            /* Update the head pointer to point at the new node.  */
            (*head) =  new_node;
        }
        else
        {

            /* We know that the new node is not the highest priority and
               must be placed somewhere after the head pointer.  */

            /* Move search pointer up to the next node since we are trying
               to find the proper node to insert in front of. */
            search_ptr =  search_ptr -> cs_next;
            while ((search_ptr -> cs_priority <= new_node -> cs_priority) &&
                   (search_ptr != (*head)))
            {

                /* Move along to the next node.  */
                search_ptr =  search_ptr -> cs_next;
            }
        }

        /* Insert before search pointer.  */
        new_node -> cs_previous =               search_ptr -> cs_previous;
        (new_node -> cs_previous) -> cs_next =  new_node;
        new_node -> cs_next =                   search_ptr;
        (new_node -> cs_next) -> cs_previous =  new_node;
    }
    else
    {

        /* The list is empty, setup the head and the new node.  */
        (*head) =  new_node;
        new_node -> cs_previous =  new_node;
        new_node -> cs_next =      new_node;
    }

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

/*************************************************************************/
/*                                                                       */
/* FUNCTION                                                              */
/*                                                                       */
/*      CSC_Remove_From_List                                             */
/*                                                                       */
/* DESCRIPTION                                                           */
/*                                                                       */
/*      This function removes the specified node from the specified      */
/*      linked list.                                                     */
/*                                                                       */
/* CALLED BY                                                             */
/*                                                                       */
/*      various components                                               */
/*                                                                       */
/* CALLS                                                                 */
/*                                                                       */
/*      None                                                             */
/*                                                                       */
/* INPUTS                                                                */
/*                                                                       */
/*      head                                Pointer to head pointer      */
/*      node                                Pointer to node to add       */
/*                                                                       */
/* OUTPUTS                                                               */
/*                                                                       */
/*      modified list                                                    */
/*                                                                       */
/* HISTORY                                                               */
/*                                                                       */
/*         NAME            DATE                    REMARKS               */
/*                                                                       */
/*      W. Lamie        03-01-1993      Created initial version 1.0      */
/*      D. Lamie        04-19-1993      Verified version 1.0             */
/*      W. Lamie        03-01-1994      Removed clearing link pointers   */
/*                                        during removal of a node from  */
/*                                        list, resulting in version 1.1 */
/*      R. Pfaff -                                                       */
/*      D. Lamie        03-18-1994      Verified version 1.1             */
/*                                                                       */
/*************************************************************************/

#ifndef NU_INLINE

VOID    CSC_Remove_From_List(CS_NODE **head, CS_NODE *node)
{
NU_SUPERV_USER_VARIABLES

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

    /* Determine if this is the only node in the system.  */
    if (node -> cs_previous == node)
    {

        /* Yes, this is the only node in the system.  Clear the node's
           pointers and the head pointer.  */
        (*head) =              NU_NULL;
    }
    else
    {

        /* Unlink the node from a multiple node list.  */
        (node -> cs_previous) -> cs_next =  node -> cs_next;
        (node -> cs_next) -> cs_previous =  node -> cs_previous;

        /* Check to see if the node to delete is at the head of the
           list. */
        if (node == *head)

            /* Move the head pointer to the node after.  */
            *head =  node -> cs_next;
    }

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

#endif