/****************************************************************************
 * net/iob/iob_copyin.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 <stdint.h>
#include <string.h>
#include <queue.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/net/iob.h>

#include "iob.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

#ifndef MIN
#  define MIN(a,b) ((a) < (b) ? (a) : (b))
#endif

/****************************************************************************
 * Private Types
 ****************************************************************************/

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Public Data
 ****************************************************************************/

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

/****************************************************************************
 * Name: iob_copyin
 *
 * Description:
 *  Copy data 'len' bytes from a user buffer into the I/O buffer chain,
 *  starting at 'offset'.
 *
 ****************************************************************************/

int iob_copyin(FAR struct iob_s *iob, FAR const uint8_t *src,
               unsigned int len, unsigned int offset)
{
  FAR uint8_t *dest;
  unsigned int ncopy;
  unsigned int avail;

  /* Skip to the I/O buffer containing the offset */

  while (offset >= iob->io_len)
    {
      offset -= iob->io_len;
      iob     = (FAR struct iob_s *)iob->io_link.flink;
    }

  /* Then loop until all of the I/O data is copied from the user buffer */

  while (len > 0)
    {
      /* Get the source I/O buffer offset address and the amount of data
       * available from that address.
       */

      dest  = &iob->io_data[offset];
      avail = CONFIG_IOB_BUFSIZE - offset;

      /* Copy from the user buffer to the I/O buffer */

      ncopy = MIN(avail, len);
      memcpy(dest, src, ncopy);

      /* Adjust the total length of the copy and the destination address in
       * the user buffer.
       */

      len -= ncopy;
      src += ncopy;

      /* Skip to the next I/O buffer in the chain.  First, check if we
       * are at the end of the buffer chain.
       */

      if (iob->io_link.flink == NULL)
        {
          struct iob_s *newiob;

          /* Yes.. allocate a new buffer */

          newiob = iob_alloc();
          if (newiob == NULL)
            {
              ndbg("ERROR: Failed to allocate I/O buffer\n");
              return -ENOMEM;
            }

          /* Add the new I/O buffer to the end of the buffer chain. */

          iob->io_link.flink = &newiob->io_link;
          iob = newiob;
        }
      else
        {
          /* Otherwise, just move to the next buffer in the list */

          iob = (FAR struct iob_s *)iob->io_link.flink;
        }

      offset = 0;
    }

  return 0;
}