设置优先权函数：op_pk_priority_set()

描述：op_pk_priority_set (pkptr, value)

功能：设置包的优先级；

返回值：void

说明：

     pkptr：指向要设置的包的指针；

     value：用户想设置的值。高数值意味着高优先级。

     注：包的优先权可以在任何时候修改和获得。

举例：

/* acquire the arriving packet */
/* multiple arriving streams are supported. */
pkptr = op_pk_get (op_intrpt_strm ());
/* new packets are stamped to */
/* indicate the packet is waiting for service. */
op_pk_priority_set (pkptr, PK_STATUS_WAITING);
/* attempt to enqueue the packet at tail of subqueue 0 */
if (op_subq_pk_insert (0, pkptr, OPC_QPOS_TAIL) != OPC_QINS_OK)
{
/* the insertion failed (due to a full queue)... */
op_pk_destroy (pkptr);
/* set flag indicating insertion failed... */
insert_ok = 0;
}