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- /****************************************************************************
- * mm/iob/iob_copyout.c
- *
- * Copyright (C) 2014 Gregory Nutt. All rights reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <stdint.h>
- #include <string.h>
- #include <assert.h>
- #include <nuttx/mm/iob.h>
- #include "iob.h"
- /****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
- #ifndef MIN
- # define MIN(a,b) ((a) < (b) ? (a) : (b))
- #endif
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: iob_copyout
- *
- * Description:
- * Copy data 'len' bytes of data into the user buffer starting at 'offset'
- * in the I/O buffer, returning that actual number of bytes copied out.
- *
- ****************************************************************************/
- int iob_copyout(FAR uint8_t *dest, FAR const struct iob_s *iob,
- unsigned int len, unsigned int offset)
- {
- FAR const uint8_t *src;
- unsigned int ncopy;
- unsigned int avail;
- unsigned int remaining;
- /* Skip to the I/O buffer containing the offset */
- while (offset >= iob->io_len)
- {
- offset -= iob->io_len;
- iob = iob->io_flink;
- if (iob == NULL)
- {
- /* We have no requested data in iob chain */
- return 0;
- }
- }
- /* Then loop until all of the I/O data is copied to the user buffer */
- remaining = len;
- while (iob && remaining > 0)
- {
- /* Get the source I/O buffer offset address and the amount of data
- * available from that address.
- */
- src = &iob->io_data[iob->io_offset + offset];
- avail = iob->io_len - offset;
- /* Copy the from the I/O buffer in to the user buffer */
- ncopy = MIN(avail, remaining);
- memcpy(dest, src, ncopy);
- /* Adjust the total length of the copy and the destination address in
- * the user buffer.
- */
- remaining -= ncopy;
- dest += ncopy;
- /* Skip to the next I/O buffer in the chain */
- iob = iob->io_flink;
- offset = 0;
- }
- return len - remaining;
- }
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