root.hh revision 12185 
1/*
2 * Copyright (c) 2011 Advanced Micro Devices, Inc.
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: Gabe Black
29 */
30
31/**
32 * @file This file defines the Root simobject and the methods used to control
33 * the time syncing mechanism provided through it.
34 *
35 * Time syncing prevents simulated time from passing faster than real time. It
36 * works by scheduling a periodic event that checks to see if its simulated
37 * period is shorter than its real period. If it is, it stalls the simulation
38 * until they're equal.
39 */
40
41#ifndef __SIM_ROOT_HH__
42#define __SIM_ROOT_HH__
43
44#include "base/time.hh"
45#include "params/Root.hh"
46#include "sim/eventq.hh"
47#include "sim/sim_object.hh"
48
49class Root : public SimObject
50{
51  private:
52    static Root *_root;
53
54  protected:
55    bool _enabled;
56    Time _period;
57    Tick _periodTick;
58    Time _spinThreshold;
59
60    Time lastTime;
61
62    void timeSync();
63    EventFunctionWrapper syncEvent;
64
65  public:
66    /**
67     * Use this function to get a pointer to the single Root object in the
68     * simulation. This function asserts that such an object has actual been
69     * constructed to avoid having to perform that check everywhere the root
70     * is used. This is to allow calling the functions below.
71     *
72     * @return Pointer to the single root object.
73     */
74    static Root *
75    root()
76    {
77        assert(_root);
78        return _root;
79    }
80
81  public:
82
83    /// Check whether time syncing is enabled.
84    bool timeSyncEnabled() const { return _enabled; }
85    /// Retrieve the period for the sync event.
86    const Time timeSyncPeriod() const { return _period; }
87    /// Retrieve the threshold for time remaining to spin wait.
88    const Time timeSyncSpinThreshold() const { return _spinThreshold; }
89
90    /// Enable or disable time syncing.
91    void timeSyncEnable(bool en);
92    /// Configure the period for time sync events.
93    void timeSyncPeriod(Time newPeriod);
94    /// Set the threshold for time remaining to spin wait.
95    void timeSyncSpinThreshold(Time newThreshold);
96
97    typedef RootParams Params;
98    const Params *
99    params() const
100    {
101        return dynamic_cast<const Params *>(_params);
102    }
103
104    Root(Params *p);
105
106    /** Schedule the timesync event at startup().
107     */
108    void startup() override;
109
110    void serialize(CheckpointOut &cp) const override;
111};
112
113#endif // __SIM_ROOT_HH__
114