/****************************************************************************
* net/iob/iob_trimhead_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>
#if defined(CONFIG_DEBUG) && defined(CONFIG_IOB_DEBUG)
/* Force debug output (from this file only) */
# undef CONFIG_DEBUG_NET
# define CONFIG_DEBUG_NET 1
#endif
#include <assert.h>
#include <debug.h>
#include <nuttx/net/iob.h>
#include "iob.h"
#if CONFIG_IOB_NCHAINS > 0
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#ifndef NULL
# define NULL ((FAR void *)0)
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: iob_trimhead_queue
*
* Description:
* Remove bytes from the beginning of an I/O chain at the head of the
* queue. Emptied I/O buffers are freed and, hence, the head of the
* queue may change.
*
* This function is just a wrapper around iob_trimhead() that assures that
* the I/O buffer chain at the head of queue is modified with the trimming
* operation.
*
* Returned Value:
* The new I/O buffer chain at the head of the queue is returned.
*
****************************************************************************/
FAR struct iob_s *iob_trimhead_queue(FAR struct iob_queue_s *qhead,
unsigned int trimlen)
{
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 = qhead->qh_head;
if (qentry)
{
/* Verify that the queue entry contains an I/O buffer chain */
iob = qentry->qe_head;
if (iob)
{
/* Trim the I/Buffer chain and update the queue head */
iob = iob_trimhead(iob, trimlen);
qentry->qe_head = iob;
}
}
/* Return the new I/O buffer chain at the head of the queue */
return iob;
}
#endif /* CONFIG_IOB_NCHAINS > 0 */
