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+/*
+ * Copyright (c) 2014 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Copyright (c) 2006 The Regents of The University of Michigan
+ * Copyright (c) 2013 Advanced Micro Devices, Inc.
+ * Copyright (c) 2013 Mark D. Hill and David A. Wood
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Nathan Binkert
+ *          Steve Reinhardt
+ *          Andrew Bardsley
+ *          Christian Menard
+ */
+
+/**
+ * @file
+ *
+ * Defines an sc_module type to wrap a gem5 simulation.  The 'evaluate'
+ * thread on that module implements the gem5 event loop.
+ *
+ * This currently only supports a single event queue and strictly
+ * cooperatively threaded SystemC threads and so there should be at
+ * most one Gem5Module instantiated in any simulation.
+ */
+
+#ifndef __SIM_SC_MODULE_HH__
+#define __SIM_SC_MODULE_HH__
+
+#include <systemc>
+
+#include "sim/eventq.hh"
+#include "sim/sim_events.hh"
+
+namespace Gem5SystemC
+{
+
+/** A SystemC module implementing the gem5 event queue.  This object
+ *  doesn't actually own any of the simulation SimObjects (those need
+ *  to be administered separately) but it does control the event
+ *  queue.
+ *
+ *  The event loop here services gem5 events in order at the current time
+ *  and then yielding to another SystemC thread.  gem5 events are not
+ *  individually scheduled in SystemC.  For this reason, asynchronous events
+ *  and function interaction (for example TLM) with gem5 from SystemC must
+ *  notify the module so that the yielding 'wait' can be interrupted.
+ *  From the point of view of another SystemC module calling into gem5,
+ *  curTick can lag SystemC time, be exactly the same time but *never*
+ *  lead SystemC time.
+ *
+ *  This functionality is wrapped in an sc_module as its intended that
+ *  the a class representing top level simulation control should be derived
+ *  from this class. */
+class Module : public sc_core::sc_channel
+{
+  protected:
+    /** Event to trigger (via. ::notify) for event scheduling from
+     *  outside gem5 */
+    sc_core::sc_event externalSchedulingEvent;
+
+    /** Event to trigger on exit of eventLoop */
+    sc_core::sc_event eventLoopExitEvent;
+
+    /** Event to trigger to enter eventLoop */
+    sc_core::sc_event eventLoopEnterEvent;
+
+    /** Expected exit time of last eventLoop sleep */
+    Tick wait_exit_time;
+
+    /** Are we in Module::simulate?  Used to mask events when not inside
+     *  the simulate loop */
+    bool in_simulate;
+
+    /** Placeholder base class for a variant event queue if this becomes
+     *  useful */
+    class SCEventQueue : public EventQueue
+    {
+      protected:
+        Module &module;
+
+      public:
+        SCEventQueue(const std::string &name,
+            Module &module_) : EventQueue(name), module(module_)
+        { }
+
+        /** Signal module to wakeup */
+        void wakeup(Tick when);
+    };
+
+    /** Service any async event marked up in the globals event_... */
+    void serviceAsyncEvent();
+
+  public:
+    /** Simulate is a process */
+    SC_HAS_PROCESS(Module);
+
+    Module(sc_core::sc_module_name name);
+
+    /** Last exitEvent from eventLoop */
+    Event *exitEvent;
+
+    /** Setup global event queues.  Call this before any other event queues
+     *  are created */
+    static void setupEventQueues(Module &module);
+
+    /** Catch gem5 time up with SystemC */
+    void catchup();
+
+    /** Notify an externalSchedulingEvent at the given time from the
+     *  current SystemC time */
+    void notify(sc_core::sc_time time_from_now = sc_core::SC_ZERO_TIME);
+
+    /** Process an event triggered by externalSchedulingEvent and also
+     *  call eventLoop (to try and mop up any events at this time) if there
+     *  are any scheduled events */
+    void serviceExternalEvent();
+
+    /** Process gem5 events up until an exit event or there are no events
+     *  left. */
+    void eventLoop();
+
+    /** Run eventLoop up to num_cycles and return the final event */
+    GlobalSimLoopExitEvent *simulate(Tick num_cycles = MaxTick);
+};
+
+/** There are assumptions throughout Gem5SystemC file that a tick is 1ps.
+ *  Make this the case */
+void setTickFrequency();
+
+}
+
+#endif // __SIM_SC_MODULE_HH__