text: /**************************************************************************/
  /*                                                                        */
  /*       Copyright (c) Microsoft Corporation. All rights reserved.        */
  /*                                                                        */
  /*       This software is licensed under the Microsoft Software License   */
  /*       Terms for Microsoft Azure RTOS. Full text of the license can be  */
  /*       found in the LICENSE file at https://aka.ms/AzureRTOS_EULA       */
  /*       and in the root directory of this software.                      */
  /*                                                                        */
  /**************************************************************************/
  
  
  /**************************************************************************/
  /**************************************************************************/
  /**                                                                       */
  /** ThreadX Component                                                     */
  /**                                                                       */
  /**   Queue                                                               */
  /**                                                                       */
  /**************************************************************************/
  /**************************************************************************/
  
  #define TX_SOURCE_CODE
  
  
  /* Include necessary system files.  */
  
  #include "tx_api.h"
  #include "tx_trace.h"
  #include "tx_thread.h"
  #include "tx_queue.h"
  
  
  /**************************************************************************/
  /*                                                                        */
  /*  FUNCTION                                               RELEASE        */
  /*                                                                        */
  /*    _tx_queue_flush                                     PORTABLE C      */
  /*                                                           6.1          */
  /*  AUTHOR                                                                */
  /*                                                                        */
  /*    William E. Lamie, Microsoft Corporation                             */
  /*                                                                        */
  /*  DESCRIPTION                                                           */
  /*                                                                        */
  /*    This function resets the specified queue, if there are any messages */
  /*    in it.  Messages waiting to be placed on the queue are also thrown  */
  /*    out.                                                                */
  /*                                                                        */
  /*  INPUT                                                                 */
  /*                                                                        */
  /*    queue_ptr                         Pointer to queue control block    */
  /*                                                                        */
  /*  OUTPUT                                                                */
  /*                                                                        */
  /*    TX_SUCCESS                        Successful completion status      */
  /*                                                                        */
  /*  CALLS                                                                 */
  /*                                                                        */
  /*    _tx_thread_system_preempt_check   Check for preemption              */
  /*    _tx_thread_system_resume          Resume thread service             */
  /*    _tx_thread_system_ni_resume       Non-interruptable resume thread   */
  /*                                                                        */
  /*  CALLED BY                                                             */
  /*                                                                        */
  /*    Application Code                                                    */
  /*                                                                        */
  /*  RELEASE HISTORY                                                       */
  /*                                                                        */
  /*    DATE              NAME                      DESCRIPTION             */
  /*                                                                        */
  /*  05-19-2020     William E. Lamie         Initial Version 6.0           */
  /*  09-30-2020     Yuxin Zhou               Modified comment(s),          */
  /*                                            resulting in version 6.1    */
  /*                                                                        */
  /**************************************************************************/
  UINT  _tx_queue_flush(TX_QUEUE *queue_ptr)
  {
  
  TX_INTERRUPT_SAVE_AREA
  
  TX_THREAD       *suspension_list;
  UINT            suspended_count;
  TX_THREAD       *thread_ptr;
  
  
      /* Initialize the suspended count and list.  */
      suspended_count =  TX_NO_SUSPENSIONS;
      suspension_list =  TX_NULL;
  
      /* Disable interrupts to reset various queue parameters.  */
      TX_DISABLE
  
      /* If trace is enabled, insert this event into the trace buffer.  */
      TX_TRACE_IN_LINE_INSERT(TX_TRACE_QUEUE_FLUSH, queue_ptr, TX_POINTER_TO_ULONG_CONVERT(&thread_ptr), 0, 0, TX_TRACE_QUEUE_EVENTS)
  
      /* Log this kernel call.  */
      TX_EL_QUEUE_FLUSH_INSERT
  
      /* Determine if there is something on the queue.  */
      if (queue_ptr -> tx_queue_enqueued != TX_NO_MESSAGES)
      {
  
          /* Yes, there is something in the queue.  */
  
          /* Reset the queue parameters to erase all of the queued messages.  */
          queue_ptr -> tx_queue_enqueued =           TX_NO_MESSAGES;
          queue_ptr -> tx_queue_available_storage =  queue_ptr -> tx_queue_capacity;
          queue_ptr -> tx_queue_read =               queue_ptr -> tx_queue_start;
          queue_ptr -> tx_queue_write =              queue_ptr -> tx_queue_start;
  
          /* Now determine if there are any threads suspended on a full queue.  */
          if (queue_ptr -> tx_queue_suspended_count != TX_NO_SUSPENSIONS)
          {
  
              /* Yes, there are threads suspended on this queue, they must be 
                 resumed!  */
  
              /* Copy the information into temporary variables.  */
              suspension_list =  queue_ptr -> tx_queue_suspension_list;
              suspended_count =  queue_ptr -> tx_queue_suspended_count;
  
              /* Clear the queue variables.  */
              queue_ptr -> tx_queue_suspension_list =  TX_NULL;
              queue_ptr -> tx_queue_suspended_count =  TX_NO_SUSPENSIONS;
  
              /* Temporarily disable preemption.  */
              _tx_thread_preempt_disable++;
          }
      }
  
      /* Restore interrupts.  */
      TX_RESTORE
  
      /* Walk through the queue list to resume any and all threads suspended
         on this queue.  */
      if (suspended_count != TX_NO_SUSPENSIONS)
      {
  
          /* Pickup the thread to resume.  */
          thread_ptr =  suspension_list;
          while (suspended_count != ((ULONG) 0))
          {
          
              /* Decrement the suspension count.  */
              suspended_count--;
  
              /* Check for a NULL thread pointer.  */
              if (thread_ptr == TX_NULL)
              {
              
                  /* Get out of the loop.  */
                  break;
              }
  
              /* Resume the next suspended thread.  */
              
              /* Lockout interrupts.  */
              TX_DISABLE
  
              /* Clear the cleanup pointer, this prevents the timeout from doing 
                 anything.  */
              thread_ptr -> tx_thread_suspend_cleanup =  TX_NULL;
  
              /* Set the return status in the thread to TX_SUCCESS.  */
              thread_ptr -> tx_thread_suspend_status =  TX_SUCCESS;
  
              /* Move the thread pointer ahead.  */
              thread_ptr =  thread_ptr -> tx_thread_suspended_next;
  
  #ifdef TX_NOT_INTERRUPTABLE
  
              /* Resume the thread!  */
              _tx_thread_system_ni_resume(thread_ptr -> tx_thread_suspended_previous);
  
              /* Restore interrupts.  */
              TX_RESTORE
  #else
  
              /* Temporarily disable preemption again.  */
              _tx_thread_preempt_disable++;
  
              /* Restore interrupts.  */
              TX_RESTORE
      
              /* Resume the thread.  */
              _tx_thread_system_resume(thread_ptr -> tx_thread_suspended_previous);
  #endif
          }
  
          /* Disable interrupts.  */
          TX_DISABLE
  
          /* Restore previous preempt posture.  */
          _tx_thread_preempt_disable--;
  
          /* Restore interrupts.  */
          TX_RESTORE
  
          /* Check for preemption.  */
          _tx_thread_system_preempt_check();
      }
  
      /* Return TX_SUCCESS.  */
      return(TX_SUCCESS);
  }
  
  