/*
* 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
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* 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 <cassert>
#include "arch/x86/types.hh"
#include "arch/x86/miscregs.hh"
#include "base/bitfield.hh"
#include "base/misc.hh"
#include "base/trace.hh"
#include "base/types.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 SizeTypeToSize[3][10];
protected:
ThreadContext * tc;
//The bytes to be predecoded
MachInst fetchChunk;
//The pc of the start of fetchChunk
Addr basePC;
//The pc the current instruction started at
Addr origPC;
//The offset into fetchChunk of current processing
int offset;
//The extended machine instruction being generated
ExtMachInst emi;
HandyM5Reg m5Reg;
inline uint8_t getNextByte()
{
return ((uint8_t *)&fetchChunk)[offset];
}
void getImmediate(int &collected, uint64_t ¤t, int size)
{
//Figure out how many bytes we still need to get for the
//immediate.
int toGet = size - collected;
//Figure out how many bytes are left in our "buffer"
int remaining = sizeof(MachInst) - offset;
//Get as much as we need, up to the amount available.
toGet = toGet > remaining ? remaining : toGet;
//Shift the bytes we want to be all the way to the right
uint64_t partialImm = fetchChunk >> (offset * 8);
//Mask off what we don't want
partialImm &= mask(toGet * 8);
//Shift it over to overlay with our displacement.
partialImm <<= (immediateCollected * 8);
//Put it into our displacement
current |= partialImm;
//Update how many bytes we've collected.
collected += toGet;
consumeBytes(toGet);
}
inline void consumeByte()
{
offset++;
assert(offset <= sizeof(MachInst));
if(offset == sizeof(MachInst))
outOfBytes = true;
}
inline void consumeBytes(int numBytes)
{
offset += numBytes;
assert(offset <= sizeof(MachInst));
if(offset == sizeof(MachInst))
outOfBytes = true;
}
void doReset();
//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;
//The size of the immediate value
int immediateSize;
//This is how much of any immediate value we've gotten. This is used
//for both the actual immediate and the displacement.
int immediateCollected;
enum State {
ResetState,
PrefixState,
OpcodeState,
ModRMState,
SIBState,
DisplacementState,
ImmediateState,
//We should never get to this state. Getting here is an error.
ErrorState
};
State state;
//Functions to handle each of the states
State doPrefixState(uint8_t);
State doOpcodeState(uint8_t);
State doModRMState(uint8_t);
State doSIBState(uint8_t);
State doDisplacementState();
State doImmediateState();
public:
Predecoder(ThreadContext * _tc) :
tc(_tc), basePC(0), origPC(0), offset(0),
outOfBytes(true), emiIsReady(false),
state(ResetState)
{
emi.mode.mode = LongMode;
emi.mode.submode = SixtyFourBitMode;
m5Reg = 0;
}
void reset()
{
state = ResetState;
}
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 pc, Addr fetchPC, MachInst data)
{
DPRINTF(Predecoder, "Getting more bytes.\n");
basePC = fetchPC;
offset = (fetchPC >= pc) ? 0 : pc - fetchPC;
fetchChunk = data;
outOfBytes = false;
process();
}
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;
}
int getInstSize()
{
DPRINTF(Predecoder,
"Calculating the instruction size: "
"basePC: %#x offset: %#x origPC: %#x\n",
basePC, offset, origPC);
return basePC + offset - origPC;
}
};
};
#endif // __ARCH_X86_PREDECODER_HH__