135 lines
3.8 KiB
C
135 lines
3.8 KiB
C
/****************************************************************************
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* mm/iob/iob_pack.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 <string.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_pack
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*
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* Description:
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* Pack all data in the I/O buffer chain so that the data offset is zero
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* and all but the final buffer in the chain are filled. Any emptied
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* buffers at the end of the chain are freed.
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*
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****************************************************************************/
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FAR struct iob_s *iob_pack(FAR struct iob_s *iob,
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enum iob_user_e producerid)
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{
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FAR struct iob_s *head;
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FAR struct iob_s *next;
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unsigned int ncopy;
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unsigned int navail;
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/* Handle special cases */
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while (iob->io_len <= 0)
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{
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iob = iob_free(iob, producerid);
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if (iob == NULL)
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{
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return NULL;
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}
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}
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/* Now remember the head of the chain (for the return value) */
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head = iob;
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/* Pack each entry in the list */
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while (iob)
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{
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next = iob->io_flink;
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/* Eliminate the data offset in this entry */
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if (iob->io_offset > 0)
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{
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memcpy(iob->io_data, &iob->io_data[iob->io_offset], iob->io_len);
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iob->io_offset = 0;
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}
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/* Is there a buffer after this one? */
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if (next)
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{
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/* How many bytes can we copy from the next I/O buffer. Limit the
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* size of the copy to the amount of free space in current I/O
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* buffer
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*/
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ncopy = next->io_len;
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navail = CONFIG_IOB_BUFSIZE - iob->io_len;
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if (ncopy > navail)
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{
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ncopy = navail;
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}
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if (ncopy > 0)
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{
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/* Copy the data from the next into
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* the current I/O buffer iob
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*/
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memcpy(&iob->io_data[iob->io_len],
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&next->io_data[next->io_offset],
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ncopy);
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/* Adjust lengths and offsets */
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iob->io_len += ncopy;
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next->io_len -= ncopy;
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next->io_offset += ncopy;
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}
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/* Have we consumed all of the data in the next entry? */
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if (next->io_len <= 0)
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{
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/* Yes.. free the next entry in I/O buffer chain */
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next = iob_free(next, producerid);
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iob->io_flink = next;
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}
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}
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/* Set up to pack the next entry in the chain */
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iob = next;
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}
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return head;
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}
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