src/mem/cache/tags/cacheset.cc

   1 /*
   2  * Copyright (c) 2009 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Lisa Hsu
  29  */
  30
  31
  32 #include "mem/cache/tags/cacheset.hh"
  33
  34 CacheBlk*
  35 CacheSet::findBlk(Addr tag) const
  36 {
  37     for (int i = 0; i < assoc; ++i) {
  38         if (blks[i]->tag == tag && blks[i]->isValid()) {
  39             return blks[i];
  40         }
  41     }
  42     return 0;
  43 }
  44
  45 void
  46 CacheSet::moveToHead(CacheBlk *blk)
  47 {
  48     // nothing to do if blk is already head
  49     if (blks[0] == blk)
  50         return;
  51
  52     // write 'next' block into blks[i], moving up from MRU toward LRU
  53     // until we overwrite the block we moved to head.
  54
  55     // start by setting up to write 'blk' into blks[0]
  56     int i = 0;
  57     CacheBlk *next = blk;
  58
  59     do {
  60         assert(i < assoc);
  61         // swap blks[i] and next
  62         CacheBlk *tmp = blks[i];
  63         blks[i] = next;
  64         next = tmp;
  65         ++i;
  66     } while (next != blk);
  67 }
  68
  69 void
  70 CacheSet::moveToTail(CacheBlk *blk)
  71 {
  72     // nothing to do if blk is already tail
  73     if (blks[assoc-1] == blk)
  74         return;
  75
  76     // write 'next' block into blks[i], moving from LRU to MRU
  77     // until we overwrite the block we moved to tail.
  78
  79     // start by setting up to write 'blk' into tail
  80     int i = assoc - 1;
  81     CacheBlk *next = blk;
  82
  83     do {
  84         assert(i >= 0);
  85         // swap blks[i] and next
  86         CacheBlk *tmp = blks[i];
  87         blks[i] = next;
  88         next = tmp;
  89         --i;
  90     } while (next != blk);
  91 }
  92