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/*
* Copyright (c) 2007 The Hewlett-Packard Development Company
* All rights reserved.
*
* Redistribution and use of this software in source and binary forms,
* with or without modification, are permitted provided that the
* following conditions are met:
*
* The software must be used only for Non-Commercial Use which means any
* use which is NOT directed to receiving any direct monetary
* compensation for, or commercial advantage from such use. Illustrative
* examples of non-commercial use are academic research, personal study,
* teaching, education and corporate research & development.
* Illustrative examples of commercial use are distributing products for
* commercial advantage and providing services using the software for
* commercial advantage.
*
* If you wish to use this software or functionality therein that may be
* covered by patents for commercial use, please contact:
* Director of Intellectual Property Licensing
* Office of Strategy and Technology
* Hewlett-Packard Company
* 1501 Page Mill Road
* Palo Alto, California 94304
*
* 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 HOLDER(s), HEWLETT-PACKARD COMPANY, nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission. No right of
* sublicense is granted herewith. Derivatives of the software and
* output created using the software may be prepared, but only for
* Non-Commercial Uses. Derivatives of the software may be shared with
* others provided: (i) the others agree to abide by the list of
* conditions herein which includes the Non-Commercial Use restrictions;
* and (ii) such Derivatives of the software include the above copyright
* notice to acknowledge the contribution from this software where
* applicable, this list of conditions and the disclaimer below.
*
* 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 __ARCH_X86_PREDECODER_HH__
#define __ARCH_X86_PREDECODER_HH__
#include "arch/x86/types.hh"
#include "sim/host.hh"
class ThreadContext;
namespace X86ISA
{
class Predecoder
{
private:
//These are defined and documented in predecoder_tables.cc
static const uint8_t Prefixes[256];
static const uint8_t UsesModRM[2][256];
static const uint8_t ImmediateType[2][256];
static const uint8_t ImmediateTypeToSize[3][10];
protected:
ThreadContext * tc;
//The bytes to be predecoded
MachInst fetchChunk;
//The pc of the start of fetchChunk
Addr basePC;
//The offset into fetchChunk of current processing
int offset;
//The extended machine instruction being generated
ExtMachInst emi;
//State machine state
protected:
//Whether or not we're out of bytes
bool outOfBytes;
//Whether we've completed generating an ExtMachInst
bool emiIsReady;
//The size of the displacement value
int displacementSize;
int displacementCollected;
//The size of the immediate value
int immediateSize;
int immediateCollected;
//These are local to some of the states. I need to turn the states
//into inline functions to clean things up a bit.
int toGet;
int remaining;
MachInst partialDisp;
enum State {
Prefix,
Opcode,
ModRM,
SIB,
Displacement,
Immediate
};
State state;
public:
Predecoder(ThreadContext * _tc) :
tc(_tc), basePC(0), offset(0),
outOfBytes(true), emiIsReady(false),
state(Prefix)
{}
ThreadContext * getTC()
{
return tc;
}
void setTC(ThreadContext * _tc)
{
tc = _tc;
}
void process();
//Use this to give data to the predecoder. This should be used
//when there is control flow.
void moreBytes(Addr currPC, Addr off, MachInst data)
{
basePC = currPC;
offset = off;
fetchChunk = data;
assert(off < sizeof(MachInst));
outOfBytes = false;
process();
}
//Use this to give data to the predecoder. This should be used
//when instructions are executed in order.
void moreBytes(MachInst machInst)
{
moreBytes(basePC + sizeof(machInst), 0, machInst);
}
bool needMoreBytes()
{
return outOfBytes;
}
bool extMachInstReady()
{
return emiIsReady;
}
//This returns a constant reference to the ExtMachInst to avoid a copy
const ExtMachInst & getExtMachInst()
{
assert(emiIsReady);
emiIsReady = false;
return emi;
}
};
};
#endif // __ARCH_X86_PREDECODER_HH__
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