ras.hh revision 7720:65d338a8dba4 
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#ifndef __CPU_O3_RAS_HH__
32#define __CPU_O3_RAS_HH__
33
34#include <vector>
35
36#include "arch/types.hh"
37#include "base/types.hh"
38#include "config/the_isa.hh"
39
40/** Return address stack class, implements a simple RAS. */
41class ReturnAddrStack
42{
43  public:
44    /** Creates a return address stack, but init() must be called prior to
45     *  use.
46     */
47    ReturnAddrStack() {}
48
49    /** Initializes RAS with a specified number of entries.
50     *  @param numEntries Number of entries in the RAS.
51     */
52    void init(unsigned numEntries);
53
54    void reset();
55
56    /** Returns the top address on the RAS. */
57    TheISA::PCState top()
58    { return addrStack[tos]; }
59
60    /** Returns the index of the top of the RAS. */
61    unsigned topIdx()
62    { return tos; }
63
64    /** Pushes an address onto the RAS. */
65    void push(const TheISA::PCState &return_addr);
66
67    /** Pops the top address from the RAS. */
68    void pop();
69
70    /** Changes index to the top of the RAS, and replaces the top address with
71     *  a new target.
72     *  @param top_entry_idx The index of the RAS that will now be the top.
73     *  @param restored The new target address of the new top of the RAS.
74     */
75    void restore(unsigned top_entry_idx, const TheISA::PCState &restored);
76
77     bool empty() { return usedEntries == 0; }
78
79     bool full() { return usedEntries == numEntries; }
80  private:
81    /** Increments the top of stack index. */
82    inline void incrTos()
83    { if (++tos == numEntries) tos = 0; }
84
85    /** Decrements the top of stack index. */
86    inline void decrTos()
87    { tos = (tos == 0 ? numEntries - 1 : tos - 1); }
88
89    /** The RAS itself. */
90    std::vector<TheISA::PCState> addrStack;
91
92    /** The number of entries in the RAS. */
93    unsigned numEntries;
94
95    /** The number of used entries in the RAS. */
96    unsigned usedEntries;
97
98    /** The top of stack index. */
99    unsigned tos;
100};
101
102#endif // __CPU_O3_RAS_HH__
103