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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 "base/bitfield.hh"
+#include "base/misc.hh"
+#include "sim/host.hh"
+
+class ThreadContext;
+
+namespace X86ISA
+{
+ class Predecoder
+ {
+ private:
+ static const uint8_t Prefixes[256];
+ static const uint8_t UsesModRM[2][256];
+
+ 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()
+ {
+ warn("About to process some bytes\n");
+ assert(!outOfBytes);
+ assert(!emiIsReady);
+ while(!emiIsReady && !outOfBytes)
+ {
+ uint8_t nextByte = (fetchChunk >> (offset * 8)) & 0xff;
+ switch(state)
+ {
+ case Prefix:
+ uint8_t prefix = Prefixes[nextByte];
+ switch(prefix)
+ {
+ //Operand size override prefixes
+ case OperandSizeOverride:
+ warn("Found operand size override prefix!\n");
+ offset++;
+ break;
+ case AddressSizeOverride:
+ warn("Found address size override prefix!\n");
+ offset++;
+ break;
+ //Segment override prefixes
+ case CSOverride:
+ warn("Found cs segment override!\n");
+ offset++;
+ break;
+ case DSOverride:
+ warn("Found ds segment override!\n");
+ offset++;
+ break;
+ case ESOverride:
+ warn("Found es segment override!\n");
+ offset++;
+ break;
+ case FSOverride:
+ warn("Found fs segment override!\n");
+ offset++;
+ break;
+ case GSOverride:
+ warn("Found gs segment override!\n");
+ offset++;
+ break;
+ case SSOverride:
+ warn("Found ss segment override!\n");
+ offset++;
+ break;
+ case Lock:
+ warn("Found lock prefix!\n");
+ offset++;
+ break;
+ case Rep:
+ warn("Found rep prefix!\n");
+ offset++;
+ break;
+ case Repne:
+ warn("Found repne prefix!\n");
+ offset++;
+ break;
+ case Rex:
+ warn("Found Rex prefix %#x!\n", nextByte);
+ offset++;
+ break;
+ case 0:
+ emi.twoByteOpcode = false;
+ state = Opcode;
+ break;
+ default:
+ panic("Unrecognized prefix %#x\n", nextByte);
+ }
+ break;
+ case Opcode:
+ if(nextByte == 0xf0)
+ {
+ warn("Found two byte opcode!\n");
+ emi.twoByteOpcode = true;
+ }
+ else
+ {
+ warn("Found opcode %#x!\n", nextByte);
+ if (UsesModRM[emi.twoByteOpcode ? 1 : 0][nextByte]) {
+ state = ModRM;
+ } else if(0 /* uses immediate */) {
+ //Figure out how big the immediate should be
+ immediateCollected = 0;
+ emi.immediate = 0;
+ state = Immediate;
+ } else {
+ emiIsReady = true;
+ state = Prefix;
+ }
+ }
+ offset++;
+ break;
+ case ModRM:
+ warn("Found modrm byte %#x!\n", nextByte);
+ if (0) {//in 16 bit mode
+ //figure out 16 bit displacement size
+ if(nextByte & 0xC7 == 0x06 ||
+ nextByte & 0xC0 == 0x40)
+ displacementSize = 1;
+ else if(nextByte & 0xC7 == 0x80)
+ displacementSize = 2;
+ else
+ displacementSize = 0;
+ } else {
+ //figure out 32/64 bit displacement size
+ if(nextByte & 0xC7 == 0x06 ||
+ nextByte & 0xC0 == 0x40)
+ displacementSize = 4;
+ else if(nextByte & 0xC7 == 0x80)
+ displacementSize = 2;
+ else
+ displacementSize = 4;
+ }
+ //If there's an SIB, get that next.
+ //There is no SIB in 16 bit mode.
+ if(nextByte & 0x7 == 4 &&
+ nextByte & 0xC0 != 0xC0) {
+ // && in 32/64 bit mode)
+ state = SIB;
+ } else if(displacementSize) {
+ displacementCollected = 0;
+ emi.displacement = 0;
+ state = Displacement;
+ } else if(immediateSize) {
+ immediateCollected = 0;
+ emi.immediate = 0;
+ state = Immediate;
+ } else {
+ emiIsReady = true;
+ state = Prefix;
+ }
+ //The ModRM byte is consumed no matter what
+ offset++;
+ break;
+ case SIB:
+ warn("Found SIB byte %#x!\n", nextByte);
+ offset++;
+ if(displacementSize) {
+ displacementCollected = 0;
+ emi.displacement = 0;
+ state = Displacement;
+ } else if(immediateSize) {
+ immediateCollected = 0;
+ emi.immediate = 0;
+ state = Immediate;
+ } else {
+ emiIsReady = true;
+ state = Prefix;
+ }
+ break;
+ case Displacement:
+ //Gather up the displacement, or at least as much of it
+ //as we can get.
+
+ //Figure out how many bytes we still need to get for the
+ //displacement.
+ toGet = displacementSize - displacementCollected;
+ //Figure out how many bytes are left in our "buffer"
+ 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
+ partialDisp = fetchChunk >> offset;
+ //Mask off what we don't want
+ partialDisp &= mask(toGet * 8);
+ //Shift it over to overlay with our displacement.
+ partialDisp <<= displacementCollected;
+ //Put it into our displacement
+ emi.displacement |= partialDisp;
+ //Update how many bytes we've collected.
+ displacementCollected += toGet;
+
+ if(displacementSize == displacementCollected) {
+ //Sign extend the displacement
+ switch(displacementSize)
+ {
+ case 1:
+ emi.displacement = sext<8>(emi.displacement);
+ break;
+ case 2:
+ emi.displacement = sext<16>(emi.displacement);
+ break;
+ case 4:
+ emi.displacement = sext<32>(emi.displacement);
+ break;
+ default:
+ panic("Undefined displacement size!\n");
+ }
+ if(immediateSize) {
+ immediateCollected = 0;
+ emi.immediate = 0;
+ state = Immediate;
+ } else {
+ emiIsReady = true;
+ state = Prefix;
+ }
+ }
+ break;
+ case Immediate:
+ //Gather up the displacement, or at least as much of it
+ //as we can get
+
+ //Figure out how many bytes we still need to get for the
+ //immediate.
+ toGet = immediateSize - immediateCollected;
+ //Figure out how many bytes are left in our "buffer"
+ 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
+ partialDisp = fetchChunk >> offset;
+ //Mask off what we don't want
+ partialDisp &= mask(toGet * 8);
+ //Shift it over to overlay with our immediate.
+ partialDisp <<= displacementCollected;
+ //Put it into our immediate
+ emi.displacement |= partialDisp;
+ //Update how many bytes we've collected.
+ displacementCollected += toGet;
+ if(immediateSize == immediateCollected)
+ {
+ emiIsReady = true;
+ state = Prefix;
+ }
+ break;
+ default:
+ panic("Unrecognized state! %d\n", state);
+ }
+ if(offset == sizeof(MachInst))
+ outOfBytes = true;
+ }
+ }
+
+ //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;
+ warn("About to call process.\n");
+ 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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