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/*
* Copyright (c) 2010 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) 2007-2008 The Florida State University
* 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: Gabe Black
* Stephen Hines
*/
#ifndef __ARCH_ARM_PREDECODER_HH__
#define __ARCH_ARM_PREDECODER_HH__
#include <cassert>
#include "arch/arm/types.hh"
#include "arch/arm/miscregs.hh"
#include "base/types.hh"
class ThreadContext;
namespace ArmISA
{
class Predecoder
{
protected:
ThreadContext * tc;
//The extended machine instruction being generated
ExtMachInst emi;
MachInst data;
bool bigThumb;
bool emiReady;
bool outOfBytes;
int offset;
ITSTATE itstate;
Addr predAddr;
bool predAddrValid;
public:
void reset()
{
bigThumb = false;
offset = 0;
emi = 0;
emiReady = false;
outOfBytes = true;
itstate = 0;
predAddr = 0;
predAddrValid = false;
}
void reset(const ExtMachInst &old_emi)
{
reset();
itstate = old_emi.newItstate;
}
Predecoder(ThreadContext * _tc) :
tc(_tc), data(0)
{
reset();
}
ThreadContext * getTC()
{
return tc;
}
void
setTC(ThreadContext * _tc)
{
tc = _tc;
}
void advanceThumbCond();
void process();
//Use this to give data to the predecoder. This should be used
//when there is control flow.
void moreBytes(const PCState &pc, Addr fetchPC, MachInst inst);
//Use this to give data to the predecoder. This should be used
//when instructions are executed in order.
void moreBytes(MachInst machInst)
{
moreBytes(0, 0, machInst);
}
inline void consumeBytes(int numBytes)
{
offset += numBytes;
assert(offset <= sizeof(MachInst));
if (offset == sizeof(MachInst))
outOfBytes = true;
}
bool needMoreBytes() const
{
return outOfBytes;
}
bool extMachInstReady() const
{
return emiReady;
}
int getInstSize() const
{
return (!emi.thumb || emi.bigThumb) ? 4 : 2;
}
//This returns a constant reference to the ExtMachInst to avoid a copy
ExtMachInst getExtMachInst(PCState &pc)
{
assert(emiReady);
ExtMachInst thisEmi = emi;
pc.npc(pc.pc() + getInstSize());
predAddrValid = true;
predAddr = pc.pc() + getInstSize();
pc.size(getInstSize());
emi = 0;
emiReady = false;
return thisEmi;
}
};
};
#endif // __ARCH_ARM_PREDECODER_HH__
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