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- /****************************************************************************
- * mm/iob/iob_peek_queue.c
- *
- * Copyright (C) 2014 Gregory Nutt. All rights reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <debug.h>
- #include <nuttx/mm/iob.h>
- #include "iob.h"
- #if CONFIG_IOB_NCHAINS > 0
- /****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
- #ifndef NULL
- # define NULL ((FAR void *)0)
- #endif
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: iob_peek_queue
- *
- * Description:
- * Return a reference to the I/O buffer chain at the head of a queue. This
- * is similar to iob_remove_queue except that the I/O buffer chain is in
- * place at the head of the queue. The I/O buffer chain may safely be
- * modified by the caller but must be removed from the queue before it can
- * be freed.
- *
- * Returned Value:
- * Returns a reference to the I/O buffer chain at the head of the queue.
- *
- ****************************************************************************/
- FAR struct iob_s *iob_peek_queue(FAR struct iob_queue_s *iobq)
- {
- FAR struct iob_qentry_s *qentry;
- FAR struct iob_s *iob = NULL;
- /* Peek at the I/O buffer chain container at the head of the queue */
- qentry = iobq->qh_head;
- if (qentry)
- {
- /* Return the I/O buffer chain from the container */
- iob = qentry->qe_head;
- }
- return iob;
- }
- #endif /* CONFIG_IOB_NCHAINS > 0 */
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