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