ras.hh revision 5865 
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 "sim/host.hh"
35#include <vector>
36
37/** Return address stack class, implements a simple RAS. */
38class ReturnAddrStack
39{
40  public:
41    /** Creates a return address stack, but init() must be called prior to
42     *  use.
43     */
44    ReturnAddrStack() {}
45
46    /** Initializes RAS with a specified number of entries.
47     *  @param numEntries Number of entries in the RAS.
48     */
49    void init(unsigned numEntries);
50
51    void reset();
52
53    /** Returns the top address on the RAS. */
54    Addr top()
55    { return addrStack[tos]; }
56
57    /** Returns the index of the top of the RAS. */
58    unsigned topIdx()
59    { return tos; }
60
61    /** Pushes an address onto the RAS. */
62    void push(const Addr &return_addr);
63
64    /** Pops the top address from the RAS. */
65    void pop();
66
67    /** Changes index to the top of the RAS, and replaces the top address with
68     *  a new target.
69     *  @param top_entry_idx The index of the RAS that will now be the top.
70     *  @param restored_target The new target address of the new top of the RAS.
71     */
72    void restore(unsigned top_entry_idx, const Addr &restored_target);
73
74     bool empty() { return usedEntries == 0; }
75
76     bool full() { return usedEntries == numEntries; }
77  private:
78    /** Increments the top of stack index. */
79    inline void incrTos()
80    { if (++tos == numEntries) tos = 0; }
81
82    /** Decrements the top of stack index. */
83    inline void decrTos()
84    { tos = (tos == 0 ? numEntries - 1 : tos - 1); }
85
86    /** The RAS itself. */
87    std::vector<Addr> addrStack;
88
89    /** The number of entries in the RAS. */
90    unsigned numEntries;
91
92    /** The number of used entries in the RAS. */
93    unsigned usedEntries;
94
95    /** The top of stack index. */
96    unsigned tos;
97};
98
99#endif // __CPU_O3_RAS_HH__
100