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- /****************************************************************************
- * drivers/bch/bchlib_read.c
- *
- * Copyright (C) 2008-2009 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 <sys/types.h>
- #include <stdint.h>
- #include <string.h>
- #include <errno.h>
- #include <assert.h>
- #include <debug.h>
- #include <nuttx/fs/fs.h>
- #include "bch_internal.h"
- /****************************************************************************
- * Private Types
- ****************************************************************************/
- /****************************************************************************
- * Private Function Prototypes
- ****************************************************************************/
- /****************************************************************************
- * Private Data
- ****************************************************************************/
- /****************************************************************************
- * Private Functions
- ****************************************************************************/
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: bchlib_read
- *
- * Description:
- * Read from the block device set-up by bchlib_setup as if it were a character
- * device.
- *
- ****************************************************************************/
- ssize_t bchlib_read(FAR void *handle, FAR char *buffer, size_t offset, size_t len)
- {
- FAR struct bchlib_s *bch = (FAR struct bchlib_s *)handle;
- size_t nsectors;
- size_t sector;
- uint16_t sectoffset;
- size_t nbytes;
- size_t bytesread;
- int ret;
- /* Get rid of this special case right away */
- if (len < 1)
- {
- return 0;
- }
- /* Convert the file position into a sector number an offset. */
- sector = offset / bch->sectsize;
- sectoffset = offset - sector * bch->sectsize;
- if (sector >= bch->nsectors)
- {
- /* Return end-of-file */
- return 0;
- }
- /* Read the initial partial sector */
- bytesread = 0;
- if (sectoffset > 0)
- {
- /* Read the sector into the sector buffer */
- bchlib_readsector(bch, sector);
- /* Copy the tail end of the sector to the user buffer */
- if (sectoffset + len > bch->sectsize)
- {
- nbytes = bch->sectsize - sectoffset;
- }
- else
- {
- nbytes = len;
- }
- memcpy(buffer, &bch->buffer[sectoffset], nbytes);
- /* Adjust pointers and counts */
- sectoffset = 0;
- sector++;
- if (sector >= bch->nsectors)
- {
- return nbytes;
- }
- bytesread = nbytes;
- buffer += nbytes;
- len -= nbytes;
- }
- /* Then read all of the full sectors following the partial sector directly
- * into the user buffer.
- */
- if (len >= bch->sectsize )
- {
- nsectors = len / bch->sectsize;
- if (sector + nsectors > bch->nsectors)
- {
- nsectors = bch->nsectors - sector;
- }
- ret = bch->inode->u.i_bops->read(bch->inode, (FAR uint8_t *)buffer,
- sector, nsectors);
- if (ret < 0)
- {
- fdbg("Read failed: %d\n");
- return ret;
- }
- /* Adjust pointers and counts */
- sectoffset = 0;
- sector += nsectors;
- nbytes = nsectors * bch->sectsize;
- bytesread += nbytes;
- if (sector >= bch->nsectors)
- {
- return bytesread;
- }
- buffer += nbytes;
- len -= nbytes;
- }
- /* Then read any partial final sector */
- if (len > 0)
- {
- /* Read the sector into the sector buffer */
- bchlib_readsector(bch, sector);
- /* Copy the head end of the sector to the user buffer */
- memcpy(buffer, bch->buffer, len);
- /* Adjust counts */
- bytesread += len;
- }
- return bytesread;
- }
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