Annotation of prex/dev/gen/null.c, Revision 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, char *, size_t *, int);
! 37: static int null_write(device_t, char *, size_t *, int);
! 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: /*
! 50: * Device I/O table
! 51: */
! 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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