238 lines
8 KiB
C++
238 lines
8 KiB
C++
/*
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* Copyright (c) 2007 The Hewlett-Packard Development Company
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* All rights reserved.
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*
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* Redistribution and use of this software in source and binary forms,
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* with or without modification, are permitted provided that the
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* following conditions are met:
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*
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* The software must be used only for Non-Commercial Use which means any
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* use which is NOT directed to receiving any direct monetary
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* compensation for, or commercial advantage from such use. Illustrative
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* examples of non-commercial use are academic research, personal study,
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* teaching, education and corporate research & development.
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* Illustrative examples of commercial use are distributing products for
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* commercial advantage and providing services using the software for
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* commercial advantage.
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*
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* If you wish to use this software or functionality therein that may be
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* covered by patents for commercial use, please contact:
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* Director of Intellectual Property Licensing
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* Office of Strategy and Technology
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* Hewlett-Packard Company
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* 1501 Page Mill Road
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* Palo Alto, California 94304
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer. Redistributions
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* in binary form must reproduce the above copyright notice, this list of
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* conditions and the following disclaimer in the documentation and/or
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* other materials provided with the distribution. Neither the name of
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* the COPYRIGHT HOLDER(s), HEWLETT-PACKARD COMPANY, nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission. No right of
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* sublicense is granted herewith. Derivatives of the software and
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* output created using the software may be prepared, but only for
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* Non-Commercial Uses. Derivatives of the software may be shared with
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* others provided: (i) the others agree to abide by the list of
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* conditions herein which includes the Non-Commercial Use restrictions;
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* and (ii) such Derivatives of the software include the above copyright
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* notice to acknowledge the contribution from this software where
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* applicable, this list of conditions and the disclaimer below.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Gabe Black
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*/
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#ifndef __ARCH_X86_PREDECODER_HH__
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#define __ARCH_X86_PREDECODER_HH__
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#include "arch/x86/types.hh"
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#include "base/bitfield.hh"
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#include "base/misc.hh"
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#include "base/trace.hh"
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#include "sim/host.hh"
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class ThreadContext;
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namespace X86ISA
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{
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class Predecoder
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{
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private:
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//These are defined and documented in predecoder_tables.cc
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static const uint8_t Prefixes[256];
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static const uint8_t UsesModRM[2][256];
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static const uint8_t ImmediateType[2][256];
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static const uint8_t SizeTypeToSize[3][10];
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protected:
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ThreadContext * tc;
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//The bytes to be predecoded
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MachInst fetchChunk;
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//The pc of the start of fetchChunk
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Addr basePC;
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//The pc the current instruction started at
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Addr origPC;
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//The offset into fetchChunk of current processing
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int offset;
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//The extended machine instruction being generated
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ExtMachInst emi;
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inline uint8_t getNextByte()
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{
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return (fetchChunk >> (offset * 8)) & 0xff;
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}
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void getImmediate(int &collected, uint64_t ¤t, int size)
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{
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//Figure out how many bytes we still need to get for the
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//immediate.
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int toGet = size - collected;
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//Figure out how many bytes are left in our "buffer"
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int remaining = sizeof(MachInst) - offset;
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//Get as much as we need, up to the amount available.
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toGet = toGet > remaining ? remaining : toGet;
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//Shift the bytes we want to be all the way to the right
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uint64_t partialDisp = fetchChunk >> (offset * 8);
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//Mask off what we don't want
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partialDisp &= mask(toGet * 8);
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//Shift it over to overlay with our displacement.
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partialDisp <<= (displacementCollected * 8);
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//Put it into our displacement
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current |= partialDisp;
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//Update how many bytes we've collected.
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collected += toGet;
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consumeBytes(toGet);
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}
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inline void consumeByte()
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{
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offset++;
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assert(offset <= sizeof(MachInst));
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if(offset == sizeof(MachInst))
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outOfBytes = true;
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}
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inline void consumeBytes(int numBytes)
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{
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offset += numBytes;
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assert(offset <= sizeof(MachInst));
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if(offset == sizeof(MachInst))
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outOfBytes = true;
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}
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void reset();
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//State machine state
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protected:
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//Whether or not we're out of bytes
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bool outOfBytes;
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//Whether we've completed generating an ExtMachInst
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bool emiIsReady;
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//The size of the displacement value
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int displacementSize;
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int displacementCollected;
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//The size of the immediate value
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int immediateSize;
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int immediateCollected;
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enum State {
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ResetState,
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PrefixState,
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OpcodeState,
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ModRMState,
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SIBState,
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DisplacementState,
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ImmediateState,
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//We should never get to this state. Getting here is an error.
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ErrorState
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};
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State state;
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//Functions to handle each of the states
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State doPrefixState(uint8_t);
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State doOpcodeState(uint8_t);
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State doModRMState(uint8_t);
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State doSIBState(uint8_t);
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State doDisplacementState();
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State doImmediateState();
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public:
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Predecoder(ThreadContext * _tc) :
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tc(_tc), basePC(0), origPC(0), offset(0),
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outOfBytes(true), emiIsReady(false),
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state(ResetState)
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{
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emi.mode.mode = LongMode;
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emi.mode.submode = SixtyFourBitMode;
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}
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ThreadContext * getTC()
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{
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return tc;
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}
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void setTC(ThreadContext * _tc)
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{
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tc = _tc;
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}
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void process();
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//Use this to give data to the predecoder. This should be used
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//when there is control flow.
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void moreBytes(Addr pc, Addr fetchPC, MachInst data)
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{
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DPRINTF(Predecoder, "Getting more bytes.\n");
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basePC = fetchPC;
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offset = (fetchPC >= pc) ? 0 : pc - fetchPC;
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fetchChunk = data;
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outOfBytes = false;
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process();
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}
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bool needMoreBytes()
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{
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return outOfBytes;
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}
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bool extMachInstReady()
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{
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return emiIsReady;
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}
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//This returns a constant reference to the ExtMachInst to avoid a copy
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const ExtMachInst & getExtMachInst()
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{
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assert(emiIsReady);
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emiIsReady = false;
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return emi;
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}
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int getInstSize()
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{
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DPRINTF(Predecoder,
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"Calculating the instruction size: "
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"basePC: %#x offset: %#x origPC: %#x\n",
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basePC, offset, origPC);
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return basePC + offset - origPC;
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}
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};
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};
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#endif // __ARCH_X86_PREDECODER_HH__
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