81 lines
2.7 KiB
C
81 lines
2.7 KiB
C
/****************************************************************************
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* mm/iob/iob_peek_queue.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <debug.h>
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#include <nuttx/mm/iob.h>
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#include "iob.h"
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#if CONFIG_IOB_NCHAINS > 0
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#ifndef NULL
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# define NULL ((FAR void *)0)
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: iob_peek_queue
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*
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* Description:
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* Return a reference to the I/O buffer chain at the head of a queue. This
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* is similar to iob_remove_queue except that the I/O buffer chain is in
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* place at the head of the queue. The I/O buffer chain may safely be
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* modified by the caller but must be removed from the queue before it can
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* be freed.
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*
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* Returned Value:
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* Returns a reference to the I/O buffer chain at the head of the queue.
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*
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****************************************************************************/
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FAR struct iob_s *iob_peek_queue(FAR struct iob_queue_s *iobq)
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{
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FAR struct iob_qentry_s *qentry;
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FAR struct iob_s *iob = NULL;
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/* Peek at the I/O buffer chain container at the head of the queue */
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qentry = iobq->qh_head;
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if (qentry)
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{
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/* Return the I/O buffer chain from the container */
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iob = qentry->qe_head;
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}
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return iob;
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}
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#endif /* CONFIG_IOB_NCHAINS > 0 */
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