112 lines
3.3 KiB
C
112 lines
3.3 KiB
C
/****************************************************************************
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* mm/iob/iob_copyout.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 <stdint.h>
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#include <sys/param.h>
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#include <string.h>
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#include <assert.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_copyout
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*
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* Description:
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* Copy data 'len' bytes of data into the user buffer starting at 'offset'
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* in the I/O buffer, returning that actual number of bytes copied out.
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*
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****************************************************************************/
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int iob_copyout(FAR uint8_t *dest, FAR const struct iob_s *iob,
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unsigned int len, int offset)
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{
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FAR const uint8_t *src;
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unsigned int ncopy;
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unsigned int avail;
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unsigned int remaining;
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/* The offset must applied to data that is in the I/O buffer chain */
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if ((int)(offset + iob->io_offset) < 0)
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{
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ioberr("ERROR: offset is before the start of data: %d < %d\n",
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offset, -(int)iob->io_offset);
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return -ESPIPE;
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}
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/* Skip to the I/O buffer containing the offset */
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while ((int)(offset - iob->io_len) >= 0)
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{
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offset -= iob->io_len;
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iob = iob->io_flink;
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if (iob == NULL)
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{
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/* We have no requested data in iob chain */
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return 0;
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}
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}
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/* Then loop until all of the I/O data is copied to the user buffer */
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remaining = len;
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while (iob && remaining > 0)
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{
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/* Get the source I/O buffer offset address and the amount of data
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* available from that address.
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*/
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src = &iob->io_data[iob->io_offset + offset];
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avail = iob->io_len - offset;
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/* Copy the from the I/O buffer in to the user buffer */
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ncopy = MIN(avail, remaining);
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memcpy(dest, src, ncopy);
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/* Adjust the total length of the copy and the destination address in
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* the user buffer.
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*/
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remaining -= ncopy;
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dest += ncopy;
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/* Skip to the next I/O buffer in the chain */
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iob = iob->io_flink;
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offset = 0;
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}
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return len - remaining;
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}
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