ras.hh revision 2307 
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_RAS_HH__
30#define __CPU_O3_RAS_HH__
31
32// For Addr type.
33#include "arch/isa_traits.hh"
34#include <vector>
35
36/** Return address stack class, implements a simple RAS. */
37class ReturnAddrStack
38{
39  public:
40    /** Creates a return address stack, but init() must be called prior to
41     *  use.
42     */
43    ReturnAddrStack() {}
44
45    /** Initializes RAS with a specified number of entries.
46     *  @param numEntries Number of entries in the RAS.
47     */
48    void init(unsigned numEntries);
49
50    void reset();
51
52    /** Returns the top address on the RAS. */
53    Addr top()
54    { return addrStack[tos]; }
55
56    /** Returns the index of the top of the RAS. */
57    unsigned topIdx()
58    { return tos; }
59
60    /** Pushes an address onto the RAS. */
61    void push(const Addr &return_addr);
62
63    /** Pops the top address from the RAS. */
64    void pop();
65
66    /** Changes index to the top of the RAS, and replaces the top address with
67     *  a new target.
68     *  @param top_entry_idx The index of the RAS that will now be the top.
69     *  @param restored_target The new target address of the new top of the RAS.
70     */
71    void restore(unsigned top_entry_idx, const Addr &restored_target);
72
73  private:
74    /** Increments the top of stack index. */
75    inline void incrTos()
76    { if (++tos == numEntries) tos = 0; }
77
78    /** Decrements the top of stack index. */
79    inline void decrTos()
80    { tos = (tos == 0 ? numEntries - 1 : tos - 1); }
81
82    /** The RAS itself. */
83    std::vector<Addr> addrStack;
84
85    /** The number of entries in the RAS. */
86    unsigned numEntries;
87
88    /** The number of used entries in the RAS. */
89    unsigned usedEntries;
90
91    /** The top of stack index. */
92    unsigned tos;
93};
94
95#endif // __CPU_O3_RAS_HH__
96