110 lines
3.9 KiB
C
110 lines
3.9 KiB
C
/****************************************************************************
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* mm/iob/iob_trimhead_queue.c
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*
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* Copyright (C) 2014 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <assert.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_trimhead_queue
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*
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* Description:
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* Remove bytes from the beginning of an I/O chain at the head of the
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* queue. Emptied I/O buffers are freed and, hence, the head of the
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* queue may change.
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*
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* This function is just a wrapper around iob_trimhead() that assures that
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* the I/O buffer chain at the head of queue is modified with the trimming
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* operation.
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*
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* Returned Value:
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* The new I/O buffer chain at the head of the queue is returned.
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*
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****************************************************************************/
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FAR struct iob_s *iob_trimhead_queue(FAR struct iob_queue_s *qhead,
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unsigned int trimlen,
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enum iob_user_e producerid)
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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 = qhead->qh_head;
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if (qentry)
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{
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/* Verify that the queue entry contains an I/O buffer chain */
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iob = qentry->qe_head;
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if (iob)
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{
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/* Trim the I/Buffer chain and update the queue head */
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iob = iob_trimhead(iob, trimlen, producerid);
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qentry->qe_head = iob;
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}
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}
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/* Return the new I/O buffer chain at the head of the queue */
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return iob;
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}
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#endif /* CONFIG_IOB_NCHAINS > 0 */
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