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- /****************************************************************************
- * drivers/bch/bchlib_read.c
- *
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership. The
- * ASF licenses this file to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance with the
- * License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
- * under the License.
- *
- ****************************************************************************/
- /****************************************************************************
- * 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 "bch.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 */
- ret = bchlib_readsector(bch, sector);
- if (ret < 0)
- {
- return ret;
- }
- /* 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 */
- 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)
- {
- ferr("ERROR: Read failed: %d\n", ret);
- return ret;
- }
- /* Adjust pointers and counts */
- 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 */
- ret = bchlib_readsector(bch, sector);
- if (ret < 0)
- {
- return ret;
- }
- /* 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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