diff options
Diffstat (limited to 'nuttx/drivers/bch/bchlib_read.c')
-rw-r--r-- | nuttx/drivers/bch/bchlib_read.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/nuttx/drivers/bch/bchlib_read.c b/nuttx/drivers/bch/bchlib_read.c new file mode 100644 index 000000000..f4fad1096 --- /dev/null +++ b/nuttx/drivers/bch/bchlib_read.c @@ -0,0 +1,203 @@ +/**************************************************************************** + * 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; +} |