cpu/o3/btb.hh

   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
  29 #ifndef __CPU_O3_CPU_BTB_HH__
  30 #define __CPU_O3_CPU_BTB_HH__
  31
  32 // For Addr type.
  33 #include "arch/isa_traits.hh"
  34
  35 class DefaultBTB
  36 {
  37   private:
  38     struct BTBEntry
  39     {
  40         BTBEntry()
  41             : tag(0), target(0), valid(false)
  42         {
  43         }
  44
  45         Addr tag;
  46         Addr target;
  47         bool valid;
  48     };
  49
  50   public:
  51     DefaultBTB(unsigned numEntries, unsigned tagBits,
  52                unsigned instShiftAmt);
  53
  54     Addr lookup(const Addr &inst_PC);
  55
  56     bool valid(const Addr &inst_PC);
  57
  58     void update(const Addr &inst_PC, const Addr &target_PC);
  59
  60   private:
  61     inline unsigned getIndex(const Addr &inst_PC);
  62
  63     inline Addr getTag(const Addr &inst_PC);
  64
  65     BTBEntry *btb;
  66
  67     unsigned numEntries;
  68
  69     unsigned idxMask;
  70
  71     unsigned tagBits;
  72
  73     unsigned tagMask;
  74
  75     unsigned instShiftAmt;
  76
  77     unsigned tagShiftAmt;
  78 };
  79
  80 #endif // __CPU_O3_CPU_BTB_HH__