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Annotation of prex-old/dev/gen/zero.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:  * zero.c - zero device
                     32:  */
                     33:
                     34: #include <driver.h>
                     35:
                     36: static int zero_read(device_t dev, char *buf, size_t *nbyte, int blkno);
                     37: static int zero_write(device_t dev, char *buf, size_t *nbyte, int blkno);
                     38: static int zero_init(void);
                     39:
                     40: /*
                     41:  * Driver structure
                     42:  */
                     43: struct driver zero_drv = {
                     44:        /* name */      "Zero device",
                     45:        /* order */     2,
                     46:        /* init */      zero_init,
                     47: };
                     48:
                     49: static struct devio zero_io = {
                     50:        /* open */      NULL,
                     51:        /* close */     NULL,
                     52:        /* read */      zero_read,
                     53:        /* write */     zero_write,
                     54:        /* ioctl */     NULL,
                     55:        /* event */     NULL,
                     56: };
                     57:
                     58: static device_t zero_dev;      /* Device object */
                     59:
                     60: /*
                     61:  * Read
                     62:  */
                     63: static int
                     64: zero_read(device_t dev, char *buf, size_t *nbyte, int blkno)
                     65: {
                     66:
                     67:        /* User buffer was already verified by kernel.  */
                     68:        memset(buf, 0, *nbyte);
                     69:        return 0;
                     70: }
                     71:
                     72: /*
                     73:  * Writing data to this device is ignored.
                     74:  */
                     75: static int
                     76: zero_write(device_t dev, char *buf, size_t *nbyte, int blkno)
                     77: {
                     78:
                     79:        return 0;
                     80: }
                     81:
                     82:
                     83: /*
                     84:  * Initialize
                     85:  */
                     86: static int
                     87: zero_init(void)
                     88: {
                     89:
                     90:        /* Create device object */
                     91:        zero_dev = device_create(&zero_io, "zero", DF_CHR);
                     92:        ASSERT(zero_dev);
                     93:        return 0;
                     94: }