px4-firmware/apps/examples/pashello/device.c

111 lines
4.0 KiB
C

/****************************************************************************
* examples/pashello/device.c
*
* Copyright (C) 2008, 2012 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.
*
****************************************************************************/
/****************************************************************************
* Compilation Switches
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <string.h>
#include <errno.h>
#include <nuttx/fs/fs.h>
#include "hello.h"
#include "pashello.h"
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static ssize_t hello_read(struct file *, char *, size_t);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations hello_fops =
{
0, /* open */
0, /* close */
hello_read, /* read */
0, /* write */
0, /* seek */
0, /* ioctl */
#ifndef CONFIG_DISABLE_POLL
0 /* poll */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
static ssize_t hello_read(struct file *filep, char *buffer, size_t len)
{
off_t offset = filep->f_pos; /* Start read position */
ssize_t nread = 0; /* Bytes read -- assume EOF */
/* Make sure that the offset is within the .pex file */
if (offset < hello_pex_len)
{
/* Make sure the read does not extend beyond the .pex file */
nread = len;
if (nread + offset > hello_pex_len)
{
nread = hello_pex_len - offset;
}
memcpy(buffer, &hello_pex[offset], nread);
filep->f_pos += nread;
}
return nread;
}
/****************************************************************************
* Public Functions
****************************************************************************/
void hello_register(void)
{
(void)register_driver("/dev/hello", &hello_fops, 0444, NULL);
}