File: [local] / prex / dev / gen / null.c (download)
Revision 1.1, Tue Aug 19 12:46:47 2008 UTC (16 years ago) by nbrk
Branch point for: MAIN
Initial revision
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/*-
* Copyright (c) 2005-2006, Kohsuke Ohtani
* All rights reserved.
*
* 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 of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
/*
* null.c - null device
*/
#include <driver.h>
static int null_read(device_t, char *, size_t *, int);
static int null_write(device_t, char *, size_t *, int);
static int null_init(void);
/*
* Driver structure
*/
struct driver null_drv = {
/* name */ "NULL device",
/* order */ 2,
/* init */ null_init,
};
/*
* Device I/O table
*/
static struct devio null_io = {
/* open */ NULL,
/* close */ NULL,
/* read */ null_read,
/* write */ null_write,
/* ioctl */ NULL,
/* event */ NULL,
};
static device_t null_dev; /* Device object */
/*
* Always returns 0 bytes as the read size.
*/
static int
null_read(device_t dev, char *buf, size_t *nbyte, int blkno)
{
*nbyte = 0;
return 0;
}
/*
* Data written to this device is discarded.
*/
static int
null_write(device_t dev, char *buf, size_t *nbyte, int blkno)
{
return 0;
}
/*
* Initialize
*/
static int
null_init(void)
{
/* Create device object */
null_dev = device_create(&null_io, "null", DF_CHR);
ASSERT(null_dev);
return 0;
}