btb.hh revision 1689 
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_BETA_CPU_BTB_HH__
30#define __CPU_BETA_CPU_BTB_HH__
31
32// For Addr type.
33#include "arch/alpha/isa_traits.hh"
34
35class 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_BETA_CPU_BTB_HH__
81