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diff --git a/src/cpu/pred/ras.hh b/src/cpu/pred/ras.hh
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+/*
+ * Copyright (c) 2004-2005 The Regents of The University of Michigan
+ * 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: Kevin Lim
+ */
+
+#ifndef __CPU_O3_RAS_HH__
+#define __CPU_O3_RAS_HH__
+
+#include <vector>
+
+#include "base/types.hh"
+
+/** Return address stack class, implements a simple RAS. */
+class ReturnAddrStack
+{
+  public:
+    /** Creates a return address stack, but init() must be called prior to
+     *  use.
+     */
+    ReturnAddrStack() {}
+
+    /** Initializes RAS with a specified number of entries.
+     *  @param numEntries Number of entries in the RAS.
+     */
+    void init(unsigned numEntries);
+
+    void reset();
+
+    /** Returns the top address on the RAS. */
+    Addr top()
+    { return addrStack[tos]; }
+
+    /** Returns the index of the top of the RAS. */
+    unsigned topIdx()
+    { return tos; }
+
+    /** Pushes an address onto the RAS. */
+    void push(const Addr &return_addr);
+
+    /** Pops the top address from the RAS. */
+    void pop();
+
+    /** Changes index to the top of the RAS, and replaces the top address with
+     *  a new target.
+     *  @param top_entry_idx The index of the RAS that will now be the top.
+     *  @param restored_target The new target address of the new top of the RAS.
+     */
+    void restore(unsigned top_entry_idx, const Addr &restored_target);
+
+     bool empty() { return usedEntries == 0; }
+
+     bool full() { return usedEntries == numEntries; }
+  private:
+    /** Increments the top of stack index. */
+    inline void incrTos()
+    { if (++tos == numEntries) tos = 0; }
+
+    /** Decrements the top of stack index. */
+    inline void decrTos()
+    { tos = (tos == 0 ? numEntries - 1 : tos - 1); }
+
+    /** The RAS itself. */
+    std::vector<Addr> addrStack;
+
+    /** The number of entries in the RAS. */
+    unsigned numEntries;
+
+    /** The number of used entries in the RAS. */
+    unsigned usedEntries;
+
+    /** The top of stack index. */
+    unsigned tos;
+};
+
+#endif // __CPU_O3_RAS_HH__