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+/*
+ * Copyright 2018 Google, Inc.
+ *
+ * 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: Gabe Black
+ */
+
+#ifndef __SYSTEMC_CORE_SCHEDULER_HH__
+#define __SYSTEMC_CORE_SCHEDULER_HH__
+
+#include "systemc/core/list.hh"
+#include "systemc/core/process.hh"
+
+namespace sc_gem5
+{
+
+typedef NodeList<Process> ProcessList;
+
+class Scheduler
+{
+  public:
+    Scheduler();
+
+    uint64_t numCycles() { return _numCycles; }
+    Process *current() { return _current; }
+
+    // Run the initialization phase.
+    void initialize();
+
+    // Run delta cycles until time needs to advance.
+    void runCycles();
+
+    // Put a process on the list of processes to be initialized.
+    void init(Process *p) { initList.pushLast(p); }
+
+    // Run the next process, if there is one.
+    void yield();
+
+    // Put a process on the ready list.
+    void
+    ready(Process *p)
+    {
+        // Clump methods together to minimize context switching.
+        if (p->procKind() == ::sc_core::SC_METHOD_PROC_)
+            readyList.pushFirst(p);
+        else
+            readyList.pushLast(p);
+    }
+
+    // Run the given process immediately, preempting whatever may be running.
+    void
+    runNow(Process *p)
+    {
+        // If a process is running, schedule it/us to run again.
+        if (_current)
+            readyList.pushFirst(_current);
+        // Schedule p to run first.
+        readyList.pushFirst(p);
+        yield();
+    }
+
+  private:
+    uint64_t _numCycles;
+
+    Process *_current;
+
+    ProcessList initList;
+    ProcessList readyList;
+
+    void evaluate();
+    void update();
+    void delta();
+};
+
+extern Scheduler scheduler;
+
+} // namespace sc_gem5
+
+#endif // __SYSTEMC_CORE_SCHEDULER_H__