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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_PRED_RAS_HH__
#define __CPU_PRED_RAS_HH__
#include <vector>
#include "arch/types.hh"
#include "base/types.hh"
#include "config/the_isa.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. */
TheISA::PCState 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 TheISA::PCState &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 The new target address of the new top of the RAS.
*/
void restore(unsigned top_entry_idx, const TheISA::PCState &restored);
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<TheISA::PCState> 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_PRED_RAS_HH__
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