usermode/library/mtm/src/mode/common/mask.h

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/*
    Copyright (C) 2011 Computer Sciences Department, 
    University of Wisconsin -- Madison

    ----------------------------------------------------------------------

    This file is part of Mnemosyne: Lightweight Persistent Memory, 
    originally developed at the University of Wisconsin -- Madison.

    Mnemosyne was originally developed primarily by Haris Volos
    with contributions from Andres Jaan Tack.

    ----------------------------------------------------------------------

    Mnemosyne is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation, version 2
    of the License.
 
    Mnemosyne is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, 
    Boston, MA  02110-1301, USA.

### END HEADER ###
*/

#ifndef MASK_H_4NASQJFA
#define MASK_H_4NASQJFA


static const mtm_word_t whole_word_mask = ~(mtm_word_t)0;


static inline
mtm_word_t masked_word(mtm_word_t old_value, mtm_word_t new_value, mtm_word_t mask)
{
        return (old_value & ~mask) | (new_value & mask);
}


static inline
mtm_word_t mask_new_value(w_entry_t* entry, const volatile mtm_word_t* written_address, const mtm_word_t this_value, const mtm_word_t this_mask)
{
        mtm_word_t new_value = this_value;
        mtm_word_t new_mask = entry->mask | this_mask;
        
        if (this_mask != whole_word_mask) {
                if (entry->mask == 0)
                        entry->value = ATOMIC_LOAD(written_address);
                
                new_value = masked_word(entry->value, this_value, this_mask);
        }
        
        entry->value = new_value;
        entry->mask  = new_mask;
        
        return entry->value;
}

#endif /* end of include guard: MASK_H_4NASQJFA */

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