129 lines
3.5 KiB
C
129 lines
3.5 KiB
C
/****************************************************************************
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* mm/iob/iob_update_pktlen.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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 <nuttx/mm/iob.h>
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#include "iob.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: iob_update_pktlen
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*
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* Description:
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* This function will update packet length of the iob, it will be
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* trimmed if the length of the iob chain is greater than the current
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* length.
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* This function will not grow the iob link, any grow operation should
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* be implemented through iob_copyin()/iob_trycopyin().
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*
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****************************************************************************/
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void iob_update_pktlen(FAR struct iob_s *iob, unsigned int pktlen)
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{
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FAR struct iob_s *penultimate;
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FAR struct iob_s *next;
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uint16_t offset = 0;
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int ninqueue = 0;
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int nrequire;
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uint16_t len;
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/* The data offset must be less than CONFIG_IOB_BUFSIZE */
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if (iob == NULL)
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{
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return;
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}
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/* Calculate the total entries of the data in the I/O buffer chain */
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next = iob;
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while (next != NULL)
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{
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ninqueue++;
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offset += next->io_offset;
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next = next->io_flink;
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}
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/* Trim inqueue entries if needed */
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nrequire = (pktlen + offset + CONFIG_IOB_BUFSIZE - 1) /
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CONFIG_IOB_BUFSIZE;
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if (nrequire == 0)
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{
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nrequire = 1;
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}
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if (nrequire < ninqueue)
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{
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/* Loop until complete the trim */
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next = iob;
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penultimate = NULL;
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while (next != NULL)
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{
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if (nrequire-- <= 0)
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{
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if (penultimate != NULL)
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{
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penultimate->io_flink = NULL;
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}
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iob_free_chain(next);
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break;
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}
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else
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{
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penultimate = next;
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next = next->io_flink;
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}
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}
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}
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iob->io_pktlen = pktlen;
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/* Update size of each iob */
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next = iob;
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while (next != NULL && pktlen > 0)
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{
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if (pktlen + next->io_offset > CONFIG_IOB_BUFSIZE)
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{
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len = CONFIG_IOB_BUFSIZE - next->io_offset;
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}
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else
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{
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len = pktlen;
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}
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next->io_len = len;
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pktlen -= len;
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next = next->io_flink;
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}
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}
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