[zbin] Fix check for existence of most recent output byte
[ipxe.git] / src / net / nullnet.c
1 /*
2 * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 * 02110-1301, USA.
18 */
19
20 FILE_LICENCE ( GPL2_OR_LATER );
21
22 #include <stdint.h>
23 #include <errno.h>
24 #include <ipxe/iobuf.h>
25 #include <ipxe/netdevice.h>
26
27 /** @file
28 *
29 * Null network device
30 *
31 */
32
33 static int null_open ( struct net_device *netdev __unused ) {
34 return -ENODEV;
35 };
36
37 static void null_close ( struct net_device *netdev __unused ) {
38 /* Do nothing */
39 };
40
41 static int null_transmit ( struct net_device *netdev __unused,
42 struct io_buffer *iobuf __unused ) {
43 return -ENODEV;
44 };
45
46 static void null_poll ( struct net_device *netdev __unused ) {
47 /* Do nothing */
48 }
49
50 static void null_irq ( struct net_device *netdev __unused,
51 int enable __unused ) {
52 /* Do nothing */
53 }
54
55 struct net_device_operations null_netdev_operations = {
56 .open = null_open,
57 .close = null_close,
58 .transmit = null_transmit,
59 .poll = null_poll,
60 .irq = null_irq,
61 };