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Annotation of prex-old/dev/gen/null.c, Revision 1.1.1.1

1.1       nbrk        1: /*-
                      2:  * Copyright (c) 2005-2006, Kohsuke Ohtani
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms, with or without
                      6:  * modification, are permitted provided that the following conditions
                      7:  * are met:
                      8:  * 1. Redistributions of source code must retain the above copyright
                      9:  *    notice, this list of conditions and the following disclaimer.
                     10:  * 2. Redistributions in binary form must reproduce the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer in the
                     12:  *    documentation and/or other materials provided with the distribution.
                     13:  * 3. Neither the name of the author nor the names of any co-contributors
                     14:  *    may be used to endorse or promote products derived from this software
                     15:  *    without specific prior written permission.
                     16:  *
                     17:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
                     18:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     19:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     20:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
                     21:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     22:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     23:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     24:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     25:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     26:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     27:  * SUCH DAMAGE.
                     28:  */
                     29:
                     30: /*
                     31:  * null.c - null device
                     32:  */
                     33:
                     34: #include <driver.h>
                     35:
                     36: static int null_read(device_t dev, char *buf, size_t *nbyte, int blkno);
                     37: static int null_write(device_t dev, char *buf, size_t *nbyte, int blkno);
                     38: static int null_init(void);
                     39:
                     40: /*
                     41:  * Driver structure
                     42:  */
                     43: struct driver null_drv = {
                     44:        /* name */      "NULL device",
                     45:        /* order */     2,
                     46:        /* init */      null_init,
                     47: };
                     48:
                     49: static struct devio null_io = {
                     50:        /* open */      NULL,
                     51:        /* close */     NULL,
                     52:        /* read */      null_read,
                     53:        /* write */     null_write,
                     54:        /* ioctl */     NULL,
                     55:        /* event */     NULL,
                     56: };
                     57:
                     58: static device_t null_dev;      /* Device object */
                     59:
                     60: /*
                     61:  * Always returns 0 bytes as the read size.
                     62:  */
                     63: static int
                     64: null_read(device_t dev, char *buf, size_t *nbyte, int blkno)
                     65: {
                     66:
                     67:        *nbyte = 0;
                     68:        return 0;
                     69: }
                     70:
                     71: /*
                     72:  * Data written to this device is discarded.
                     73:  */
                     74: static int
                     75: null_write(device_t dev, char *buf, size_t *nbyte, int blkno)
                     76: {
                     77:
                     78:        return 0;
                     79: }
                     80:
                     81:
                     82: /*
                     83:  * Initialize
                     84:  */
                     85: static int
                     86: null_init(void)
                     87: {
                     88:
                     89:        /* Create device object */
                     90:        null_dev = device_create(&null_io, "null", DF_CHR);
                     91:        ASSERT(null_dev);
                     92:        return 0;
                     93: }