iPXE
bitbash.c
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00001 /*
00002  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
00003  *
00004  * This program is free software; you can redistribute it and/or
00005  * modify it under the terms of the GNU General Public License as
00006  * published by the Free Software Foundation; either version 2 of the
00007  * License, or any later version.
00008  *
00009  * This program is distributed in the hope that it will be useful, but
00010  * WITHOUT ANY WARRANTY; without even the implied warranty of
00011  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012  * General Public License for more details.
00013  *
00014  * You should have received a copy of the GNU General Public License
00015  * along with this program; if not, write to the Free Software
00016  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
00017  * 02110-1301, USA.
00018  *
00019  * You can also choose to distribute this program under the terms of
00020  * the Unmodified Binary Distribution Licence (as given in the file
00021  * COPYING.UBDL), provided that you have satisfied its requirements.
00022  */
00023 
00024 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
00025 
00026 #include <ipxe/bitbash.h>
00027 
00028 /** @file
00029  *
00030  * Bit-bashing interfaces
00031  *
00032  */
00033 
00034 /**
00035  * Set/clear output bit
00036  *
00037  * @v basher            Bit-bashing interface
00038  * @v bit_id            Bit number
00039  * @v data              Value to write
00040  * 
00041  * If @c data is 0, a logic 0 will be written.  If @c data is
00042  * non-zero, a logic 1 will be written.
00043  */
00044 void write_bit ( struct bit_basher *basher, unsigned int bit_id,
00045                  unsigned long data ) {
00046         basher->op->write ( basher, bit_id, ( data ? -1UL : 0 ) );
00047 }
00048 
00049 /**
00050  * Read input bit
00051  *
00052  * @v basher            Bit-bashing interface
00053  * @v bit_id            Bit number
00054  * @ret data            Value read
00055  *
00056  * @c data will always be either 0 or -1UL.  The idea is that the
00057  * caller can simply binary-AND the returned value with whatever mask
00058  * it needs to apply.
00059  */
00060 int read_bit ( struct bit_basher *basher, unsigned int bit_id ) {
00061         return ( basher->op->read ( basher, bit_id ) ? -1UL : 0 );
00062 }