src/cpu/pred/ras.cc

   1 /*
   2  * Copyright (c) 2004-2005 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: Kevin Lim
  29  */
  30
  31 #include "cpu/pred/ras.hh"
  32
  33 void
  34 ReturnAddrStack::init(unsigned _numEntries)
  35 {
  36      numEntries  = _numEntries;
  37      addrStack.resize(numEntries);
  38      reset();
  39 }
  40
  41 void
  42 ReturnAddrStack::reset()
  43 {
  44     usedEntries = 0;
  45     tos = 0;
  46     for (unsigned i = 0; i < numEntries; ++i)
  47         addrStack[i].set(0);
  48 }
  49
  50 void
  51 ReturnAddrStack::push(const TheISA::PCState &return_addr)
  52 {
  53     incrTos();
  54
  55     addrStack[tos] = return_addr;
  56
  57     if (usedEntries != numEntries) {
  58         ++usedEntries;
  59     }
  60 }
  61
  62 void
  63 ReturnAddrStack::pop()
  64 {
  65     if (usedEntries > 0) {
  66         --usedEntries;
  67     }
  68
  69     decrTos();
  70 }
  71
  72 void
  73 ReturnAddrStack::restore(unsigned top_entry_idx,
  74                          const TheISA::PCState &restored)
  75 {
  76     tos = top_entry_idx;
  77
  78     addrStack[tos] = restored;
  79 }