nuttx/mm/iob/iob_add_queue.c

/****************************************************************************
 * mm/iob/iob_add_queue.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <assert.h>
#include <errno.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

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: iob_add_queue_internal
 *
 * Description:
 *   Add one I/O buffer chain to the end of a queue.  May fail due to lack
 *   of resources.
 *
 ****************************************************************************/

static int iob_add_queue_internal(FAR struct iob_s *iob,
                                  FAR struct iob_queue_s *iobq,
                                  FAR struct iob_qentry_s *qentry)
{
  /* Add the I/O buffer chain to the container */

  qentry->qe_head = iob;

  /* Add the container to the end of the queue */

  qentry->qe_flink = NULL;
  if (!iobq->qh_head)
    {
      iobq->qh_head = qentry;
      iobq->qh_tail = qentry;
    }
  else
    {
      DEBUGASSERT(iobq->qh_tail);
      iobq->qh_tail->qe_flink = qentry;
      iobq->qh_tail = qentry;
    }

  return 0;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: iob_add_queue
 *
 * Description:
 *   Add one I/O buffer chain to the end of a queue.  May fail due to lack
 *   of resources.
 *
 ****************************************************************************/

int iob_add_queue(FAR struct iob_s *iob, FAR struct iob_queue_s *iobq)
{
  FAR struct iob_qentry_s *qentry;

  /* Allocate a container to hold the I/O buffer chain */

  qentry = iob_alloc_qentry();
  if (!qentry)
    {
      ioberr("ERROR: Failed to allocate a container\n");
      return -ENOMEM;
    }

  return iob_add_queue_internal(iob, iobq, qentry);
}

/****************************************************************************
 * Name: iob_tryadd_queue
 *
 * Description:
 *   Add one I/O buffer chain to the end of a queue without waiting for
 *   resources to become free.
 *
 ****************************************************************************/

int iob_tryadd_queue(FAR struct iob_s *iob, FAR struct iob_queue_s *iobq)
{
  FAR struct iob_qentry_s *qentry;

  /* Allocate a container to hold the I/O buffer chain */

  qentry = iob_tryalloc_qentry();
  if (!qentry)
    {
      ioberr("ERROR: Failed to allocate a container\n");
      return -ENOMEM;
    }

  return iob_add_queue_internal(iob, iobq, qentry);
}
#endif /* CONFIG_IOB_NCHAINS > 0 */