125 lines
4.1 KiB
C
125 lines
4.1 KiB
C
/****************************************************************************
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* mm/iob/iob_copyout.c
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*
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* Copyright (C) 2014 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <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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* Pre-processor Definitions
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****************************************************************************/
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#ifndef MIN
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# define MIN(a,b) ((a) < (b) ? (a) : (b))
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#endif
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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, unsigned 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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/* Skip to the I/O buffer containing the offset */
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while (offset >= iob->io_len)
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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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