151 lines
4.7 KiB
C
151 lines
4.7 KiB
C
/****************************************************************************
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* drivers/iob/iob_pack.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 <string.h>
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#include <nuttx/drivers/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_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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{
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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);
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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 the current I/O buffer iob */
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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);
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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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