/****************************************************************************
* 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;
}
