Annotation of prex-old/dev/gen/null.c, Revision 1.1.1.1.2.1
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:
1.1.1.1.2.1! nbrk 36: static int null_read(device_t, char *, size_t *, int);
! 37: static int null_write(device_t, char *, size_t *, int);
1.1 nbrk 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:
1.1.1.1.2.1! nbrk 49: /*
! 50: * Device I/O table
! 51: */
1.1 nbrk 52: static struct devio null_io = {
53: /* open */ NULL,
54: /* close */ NULL,
55: /* read */ null_read,
56: /* write */ null_write,
57: /* ioctl */ NULL,
58: /* event */ NULL,
59: };
60:
61: static device_t null_dev; /* Device object */
62:
63: /*
64: * Always returns 0 bytes as the read size.
65: */
66: static int
67: null_read(device_t dev, char *buf, size_t *nbyte, int blkno)
68: {
69:
70: *nbyte = 0;
71: return 0;
72: }
73:
74: /*
75: * Data written to this device is discarded.
76: */
77: static int
78: null_write(device_t dev, char *buf, size_t *nbyte, int blkno)
79: {
80:
81: return 0;
82: }
83:
84:
85: /*
86: * Initialize
87: */
88: static int
89: null_init(void)
90: {
91:
92: /* Create device object */
93: null_dev = device_create(&null_io, "null", DF_CHR);
94: ASSERT(null_dev);
95: return 0;
96: }
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