128 lines
4.0 KiB
C
128 lines
4.0 KiB
C
/****************************************************************************
|
|
* mm/iob/iob_trimhead.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 <debug.h>
|
|
|
|
#include <nuttx/mm/iob.h>
|
|
|
|
#include "iob.h"
|
|
|
|
/****************************************************************************
|
|
* Pre-processor Definitions
|
|
****************************************************************************/
|
|
|
|
#ifndef NULL
|
|
# define NULL ((FAR void *)0)
|
|
#endif
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: iob_trimhead
|
|
*
|
|
* Description:
|
|
* Remove bytes from the beginning of an I/O chain. Emptied I/O buffers
|
|
* are freed and, hence, the beginning of the chain may change.
|
|
*
|
|
****************************************************************************/
|
|
|
|
FAR struct iob_s *iob_trimhead(FAR struct iob_s *iob, unsigned int trimlen,
|
|
enum iob_user_e producerid)
|
|
{
|
|
unsigned int pktlen;
|
|
|
|
iobinfo("iob=%p trimlen=%d\n", iob, trimlen);
|
|
|
|
if (iob && trimlen > 0)
|
|
{
|
|
/* Trim from the head of the I/O buffer chain */
|
|
|
|
pktlen = iob->io_pktlen;
|
|
while (trimlen > 0 && iob != NULL)
|
|
{
|
|
/* Do we trim this entire I/O buffer away? */
|
|
|
|
iobinfo("iob=%p io_len=%d pktlen=%d trimlen=%d\n",
|
|
iob, iob->io_len, pktlen, trimlen);
|
|
|
|
if (iob->io_len <= trimlen)
|
|
{
|
|
FAR struct iob_s *next;
|
|
|
|
/* Decrement the trim length and packet length by the full
|
|
* data size.
|
|
*/
|
|
|
|
pktlen -= iob->io_len;
|
|
trimlen -= iob->io_len;
|
|
|
|
/* Check if this was the last entry in the chain */
|
|
|
|
next = iob->io_flink;
|
|
if (next == NULL)
|
|
{
|
|
/* Yes.. break out of the loop returning the empty
|
|
* I/O buffer chain containing only one empty entry.
|
|
*/
|
|
|
|
DEBUGASSERT(pktlen == 0);
|
|
iob->io_len = 0;
|
|
iob->io_offset = 0;
|
|
break;
|
|
}
|
|
|
|
/* Free this entry and set the next I/O buffer as the head */
|
|
|
|
iobinfo("iob=%p: Freeing\n", iob);
|
|
iob_free(iob, producerid);
|
|
iob = next;
|
|
}
|
|
else
|
|
{
|
|
/* No, then just take what we need from this I/O buffer and
|
|
* stop the trim.
|
|
*/
|
|
|
|
pktlen -= trimlen;
|
|
iob->io_len -= trimlen;
|
|
iob->io_offset += trimlen;
|
|
trimlen = 0;
|
|
}
|
|
}
|
|
|
|
/* Adjust the pktlen by the number of bytes removed from the head
|
|
* of the I/O buffer chain.
|
|
*/
|
|
|
|
iob->io_pktlen = pktlen;
|
|
}
|
|
|
|
return iob;
|
|
}
|