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Annotation of prex-old/dev/gen/zero.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:  * zero.c - zero device
                     32:  */
                     33:
                     34: #include <driver.h>
                     35:
1.1.1.1.2.1! nbrk       36: static int zero_read(device_t, char *, size_t *, int);
        !            37: static int zero_write(device_t, char *, size_t *, int);
1.1       nbrk       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:
1.1.1.1.2.1! nbrk       49: /*
        !            50:  * Device I/O table
        !            51:  */
1.1       nbrk       52: static struct devio zero_io = {
                     53:        /* open */      NULL,
                     54:        /* close */     NULL,
                     55:        /* read */      zero_read,
                     56:        /* write */     zero_write,
                     57:        /* ioctl */     NULL,
                     58:        /* event */     NULL,
                     59: };
                     60:
                     61: static device_t zero_dev;      /* Device object */
                     62:
                     63: /*
                     64:  * Read
                     65:  */
                     66: static int
                     67: zero_read(device_t dev, char *buf, size_t *nbyte, int blkno)
                     68: {
1.1.1.1.2.1! nbrk       69:        void *kbuf;
1.1       nbrk       70:
1.1.1.1.2.1! nbrk       71:        /* Translate buffer address to kernel address */
        !            72:        kbuf = kmem_map(buf, *nbyte);
        !            73:        if (kbuf == NULL)
        !            74:                return EFAULT;
        !            75:        memset(kbuf, 0, *nbyte);
1.1       nbrk       76:        return 0;
                     77: }
                     78:
                     79: /*
                     80:  * Writing data to this device is ignored.
                     81:  */
                     82: static int
                     83: zero_write(device_t dev, char *buf, size_t *nbyte, int blkno)
                     84: {
                     85:
                     86:        return 0;
                     87: }
                     88:
                     89:
                     90: /*
                     91:  * Initialize
                     92:  */
                     93: static int
                     94: zero_init(void)
                     95: {
                     96:
                     97:        /* Create device object */
                     98:        zero_dev = device_create(&zero_io, "zero", DF_CHR);
                     99:        ASSERT(zero_dev);
                    100:        return 0;
                    101: }