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Block-to-character driver
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1235 42af7a65-404d-4744-a932-0658087f49c3
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patacongo
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/****************************************************************************
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* drivers/bch/bchlib_read.c
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*
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* Copyright (C) 2008 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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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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* Compilation Switches
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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 <sys/types.h>
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#include <string.h>
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#include <errno.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/fs.h>
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#include "bch_internal.h"
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: bchlib_read
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*
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* Description:
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* Read from the block device set-up by bchlib_setup as if it were a character
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* device.
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*
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****************************************************************************/
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ssize_t bchlib_read(FAR void *handle, FAR char *buffer, size_t offset, size_t len)
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{
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FAR struct bchlib_s *bch;
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size_t nsectors;
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size_t sector;
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uint16 sectoffset;
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size_t nbytes;
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size_t bytesread;
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int ret;
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/* Get rid of this special case right away */
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if (len < 1)
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{
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return 0;
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}
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/* Convert the file position into a sector number an offset. */
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sector = offset / bch->sectsize;
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sectoffset = offset - sector * bch->sectsize;
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if (sector >= bch->nsectors)
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{
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/* Return end-of-file */
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return 0;
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}
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/* Read the initial partial sector */
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bytesread = 0;
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if (sectoffset > 0)
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{
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/* Read the sector into the sector buffer */
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bchlib_readsector(bch, sector);
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/* Copy the tail end of the sector to the user buffer */
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if (sectoffset + len > bch->sectsize)
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{
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nbytes = bch->sectsize - sectoffset;
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}
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else
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{
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nbytes = len;
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}
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memcpy(buffer, &bch->buffer[sectoffset], nbytes);
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/* Adjust pointers and counts */
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sectoffset = 0;
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sector++;
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if (sector >= bch->nsectors)
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{
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return nbytes;
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}
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bytesread = nbytes;
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buffer += nbytes;
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len -= nbytes;
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}
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/* Then read all of the full sectors following the partial sector */
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if (len >= bch->sectsize )
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{
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nsectors = len / bch->sectsize;
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if (sector + nsectors > bch->nsectors)
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{
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nsectors = bch->nsectors - sector;
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}
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ret = bch->inode->u.i_bops->read(bch->inode, bch->buffer, sector, nsectors);
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if (ret < 0)
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{
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fdbg("Read failed: %d\n");
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return ret;
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}
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/* Adjust pointers and counts */
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sectoffset = 0;
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sector += nsectors;
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nbytes = nsectors * bch->sectsize;
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bytesread += nbytes;
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if (sector >= bch->nsectors)
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{
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return bytesread;
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}
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buffer += nbytes;
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len -= nbytes;
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}
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/* Then read any partial final sector */
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if (len > 0)
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{
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/* Read the sector into the sector buffer */
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bchlib_readsector(bch, sector);
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/* Copy the head end of the sector to the user buffer */
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memcpy(buffer, bch->buffer, len);
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/* Adjust counts */
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bytesread += len;
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}
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return bytesread;
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}
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/****************************************************************************
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* Name: bchlib_write
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*
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* Description:
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* Write to the block device set-up by bchlib_setup as if it were a character
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* device.
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*
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****************************************************************************/
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ssize_t bchlib_write(FAR void *handle, FAR const char *buffer, size_t offset, size_t len)
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{
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FAR struct bchlib_s *bch;
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size_t nsectors;
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size_t sector;
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uint16 sectoffset;
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size_t nbytes;
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size_t byteswritten;
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int ret;
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/* Get rid of this special case right away */
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if (len < 1)
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{
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return 0;
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}
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/* Convert the file position into a sector number an offset. */
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sector = offset / bch->sectsize;
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sectoffset = offset - sector * bch->sectsize;
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if (sector >= bch->nsectors)
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{
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return -EFBIG;
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}
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/* Write the initial partial sector */
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byteswritten = 0;
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if (sectoffset > 0)
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{
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/* Read the full sector into the sector buffer */
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bchlib_readsector(bch, sector);
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/* Copy the tail end of the sector from the user buffer */
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if (sectoffset + len > bch->sectsize)
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{
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nbytes = bch->sectsize - sectoffset;
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}
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else
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{
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nbytes = len;
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}
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memcpy(&bch->buffer[sectoffset], buffer, nbytes);
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bch->dirty = TRUE;
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/* Adjust pointers and counts */
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sectoffset = 0;
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sector++;
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if (sector >= bch->nsectors)
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{
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return nbytes;
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}
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byteswritten = nbytes;
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buffer += nbytes;
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len -= nbytes;
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}
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/* Then write all of the full sectors following the partial sector */
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if (len >= bch->sectsize )
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{
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nsectors = len / bch->sectsize;
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if (sector + nsectors > bch->nsectors)
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{
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nsectors = bch->nsectors - sector;
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}
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/* Write the contiguous sectors */
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ret = bch->inode->u.i_bops->write(bch->inode, bch->buffer, sector, nsectors);
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if (ret < 0)
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{
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fdbg("Write failed: %d\n");
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return ret;
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}
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/* Adjust pointers and counts */
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sectoffset = 0;
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sector += nsectors;
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nbytes = nsectors * bch->sectsize;
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byteswritten += nbytes;
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if (sector >= bch->nsectors)
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{
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return byteswritten;
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}
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buffer += nbytes;
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len -= nbytes;
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}
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/* Then write any partial final sector */
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if (len > 0)
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{
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/* Read the sector into the sector buffer */
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bchlib_readsector(bch, sector);
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/* Copy the head end of the sector from the user buffer */
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memcpy(bch->buffer, buffer, len);
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bch->dirty = TRUE;
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/* Adjust counts */
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byteswritten += len;
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}
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return byteswritten;
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}
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