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., 675 Mass Ave, Cambridge, MA 02139, USA.
17 */
18
19 FILE_LICENCE ( GPL2_OR_LATER );
20
21 #include <gpxe/bitbash.h>
22
23 /** @file
24 *
25 * Bit-bashing interfaces
26 *
27 */
28
29 /**
30 * Set/clear output bit
31 *
32 * @v basher Bit-bashing interface
33 * @v bit_id Bit number
34 * @v data Value to write
35 *
36 * If @c data is 0, a logic 0 will be written. If @c data is
37 * non-zero, a logic 1 will be written.
38 */
write_bit(struct bit_basher * basher,unsigned int bit_id,unsigned long data)39 void write_bit ( struct bit_basher *basher, unsigned int bit_id,
40 unsigned long data ) {
41 basher->op->write ( basher, bit_id, ( data ? -1UL : 0 ) );
42 }
43
44 /**
45 * Read input bit
46 *
47 * @v basher Bit-bashing interface
48 * @v bit_id Bit number
49 * @ret data Value read
50 *
51 * @c data will always be either 0 or -1UL. The idea is that the
52 * caller can simply binary-AND the returned value with whatever mask
53 * it needs to apply.
54 */
read_bit(struct bit_basher * basher,unsigned int bit_id)55 int read_bit ( struct bit_basher *basher, unsigned int bit_id ) {
56 return ( basher->op->read ( basher, bit_id ) ? -1UL : 0 );
57 }
58