src/mem/cache/tags/cacheset.cc

/*
 * Copyright (c) 2009 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Lisa Hsu
 */


#include "mem/cache/tags/cacheset.hh"

CacheBlk*
CacheSet::findBlk(Addr tag) const
{
    for (int i = 0; i < assoc; ++i) {
        if (blks[i]->tag == tag && blks[i]->isValid()) {
            return blks[i];
        }
    }
    return 0;
}

void
CacheSet::moveToHead(CacheBlk *blk)
{
    // nothing to do if blk is already head
    if (blks[0] == blk)
        return;

    // write 'next' block into blks[i], moving up from MRU toward LRU
    // until we overwrite the block we moved to head.

    // start by setting up to write 'blk' into blks[0]
    int i = 0;
    CacheBlk *next = blk;

    do {
        assert(i < assoc);
        // swap blks[i] and next
        CacheBlk *tmp = blks[i];
        blks[i] = next;
        next = tmp;
        ++i;
    } while (next != blk);
}

void
CacheSet::moveToTail(CacheBlk *blk)
{
    // nothing to do if blk is already tail
    if (blks[assoc-1] == blk)
        return;

    // write 'next' block into blks[i], moving from LRU to MRU
    // until we overwrite the block we moved to tail.

    // start by setting up to write 'blk' into tail
    int i = assoc - 1;
    CacheBlk *next = blk;

    do {
        assert(i >= 0);
        // swap blks[i] and next
        CacheBlk *tmp = blks[i];
        blks[i] = next;
        next = tmp;
        --i;
    } while (next != blk);
}