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px4-firmware/nuttx/fs/nxffs/nxffs_cache.c

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/****************************************************************************
* fs/nxffs/nxffs_cache.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* References: Linux/Documentation/filesystems/romfs.txt
*
* 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 <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/mtd.h>
#include "nxffs.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Types
****************************************************************************/
/****************************************************************************
* Public Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxffs_rdcache
*
* Description:
* Read one I/O block into the volume block cache memory.
*
* Input Parameters:
* volume - Describes the current volume
* block - The first logical block to read
*
* Returned Value:
* Negated errnos are returned only in the case of MTD reported failures.
* Nothing in the volume data itself will generate errors.
*
****************************************************************************/
int nxffs_rdcache(FAR struct nxffs_volume_s *volume, off_t block)
{
size_t nxfrd;
/* Check if the requested data is already in the cache */
if (block != volume->cblock)
{
/* Read the specified blocks into cache */
nxfrd = MTD_BREAD(volume->mtd, block, 1, volume->cache);
if (nxfrd != 1)
{
fvdbg("Read block %d failed: %d\n", block, nxfrd);
return -EIO;
}
/* Remember what is in the cache */
volume->cblock = block;
}
return OK;
}
/****************************************************************************
* Name: nxffs_wrcache
*
* Description:
* Write one or more logical blocks from the volume cache memory.
*
* Input Parameters:
* volume - Describes the current volume
*
* Returned Value:
* Negated errnos are returned only in the case of MTD reported failures.
*
****************************************************************************/
int nxffs_wrcache(FAR struct nxffs_volume_s *volume)
{
size_t nxfrd;
/* Write the current block from the cache */
nxfrd = MTD_BWRITE(volume->mtd, volume->cblock, 1, volume->cache);
if (nxfrd != 1)
{
fdbg("Write block %d failed: %d\n", volume->cblock, nxfrd);
return -EIO;
}
/* Write was successful */
return OK;
}
/****************************************************************************
* Name: nxffs_ioseek
*
* Description:
* Seek to a position in FLASH memory. This simply sets up the offsets
* and pointer values. This is a necessary step prior to using
* nxffs_getc().
*
* Input Parameters:
* volume - Describes the NXFFS volume
* offset - The physical offset in bytes from the beginning of the FLASH
* in bytes.
*
****************************************************************************/
void nxffs_ioseek(FAR struct nxffs_volume_s *volume, off_t offset)
{
/* Convert the offset into a block number and a byte offset into the
* block.
*/
volume->ioblock = offset / volume->geo.blocksize;
volume->iooffset = offset - volume->geo.blocksize * volume->ioblock;
}
/****************************************************************************
* Name: nxffs_iotell
*
* Description:
* Report the current position.
*
* Input Parameters:
* volume - Describes the NXFFS volume
*
* Returned Value:
* The offset from the beginning of FLASH to the current seek position.
*
****************************************************************************/
off_t nxffs_iotell(FAR struct nxffs_volume_s *volume)
{
return volume->ioblock * volume->geo.blocksize + volume->iooffset;
}
/****************************************************************************
* Name: nxffs_getc
*
* Description:
* Get the next byte from FLASH. This function allows the data in the
* formatted FLASH blocks to be read as a continuous byte stream, skipping
* over bad blocks and block headers as necessary.
*
* Input Parameters:
* volume - Describes the NXFFS volume. The paramters ioblock and iooffset
* in the volume structure determine the behavior of nxffs_getc().
* reserve - If less than this much space is available at the end of the
* block, then skip to the next block.
*
* Returned Value:
* Zero is returned on success. Otherwise, a negated errno indicating the
* nature of the failure.
*
****************************************************************************/
int nxffs_getc(FAR struct nxffs_volume_s *volume, uint16_t reserve)
{
int ret;
DEBUGASSERT(reserve > 0);
/* Loop to skip over bad blocks */
do
{
/* Check if we have the reserve amount at the end of the current block */
if (volume->iooffset + reserve > volume->geo.blocksize)
{
/* Check for attempt to read past the end of FLASH */
off_t nextblock = volume->ioblock + 1;
if (nextblock >= volume->nblocks)
{
fvdbg("End of FLASH encountered\n");
return -ENOSPC;
}
/* Set up the seek to the data just after the header in the
* next block.
*/
volume->ioblock = nextblock;
volume->iooffset = SIZEOF_NXFFS_BLOCK_HDR;
}
/* Make sure that the block is in the cache. The special error
* -ENOENT indicates the block was read successfully but was not
* marked as a good block. In this case we need to skip to the
* next block. All other errors are fatal.
*/
ret = nxffs_verifyblock(volume, volume->ioblock);
if (ret < 0 && ret != -ENOENT)
{
fvdbg("Failed to read valid data into cache: %d\n", ret);
return ret;
}
}
while (ret != OK);
/* Return the the character at this offset. Note that on return,
* iooffset could point to the byte outside of the current block.
*/
ret = (int)volume->cache[volume->iooffset];
volume->iooffset++;
return ret;
}
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