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Diffstat (limited to 'src/arch/x86/predecoder.hh')
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diff --git a/src/arch/x86/predecoder.hh b/src/arch/x86/predecoder.hh new file mode 100644 index 000000000..d7734be88 --- /dev/null +++ b/src/arch/x86/predecoder.hh @@ -0,0 +1,225 @@ +/* + * 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 "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; + + inline uint8_t getNextByte() + { + return (fetchChunk >> (offset * 8)) & 0xff; + } + + 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 partialDisp = fetchChunk >> (offset * 8); + //Mask off what we don't want + partialDisp &= mask(toGet * 8); + //Shift it over to overlay with our displacement. + partialDisp <<= (displacementCollected * 8); + //Put it into our displacement + current |= partialDisp; + //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; + } + + //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; + + enum State { + Prefix, + Opcode, + ModRM, + SIB, + Displacement, + Immediate, + //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), 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__ |