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Annotation of qemu/roms/ipxe/src/drivers/bitbash/bitbash.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (C) 2006 Michael Brown <[email protected]>.
                      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 <ipxe/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:  */
                     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:  */
                     55: int read_bit ( struct bit_basher *basher, unsigned int bit_id ) {
                     56:        return ( basher->op->read ( basher, bit_id ) ? -1UL : 0 );
                     57: }

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