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CLK/InstructionSets/x86/Decoder.cpp
Thomas Harte 1afcbba218 Clarify sign extension availability.
2022-03-05 16:44:26 -05:00

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//
// x86.cpp
// Clock Signal
//
// Created by Thomas Harte on 01/01/21.
// Copyright © 2021 Thomas Harte. All rights reserved.
//
#include "Decoder.hpp"
#include <algorithm>
#include <cassert>
#include <utility>
using namespace InstructionSet::x86;
template <Model model>
std::pair<int, typename Decoder<model>::InstructionT> Decoder<model>::decode(const uint8_t *source, size_t length) {
const uint8_t *const end = source + length;
// MARK: - Prefixes (if present) and the opcode.
/// Helper macro for those that follow.
#define SetOpSrcDestSize(op, src, dest, size) \
operation_ = Operation::op; \
source_ = Source::src; \
destination_ = Source::dest; \
operation_size_ = size
/// Covers anything which is complete as soon as the opcode is encountered.
#define Complete(op, src, dest, size) \
SetOpSrcDestSize(op, src, dest, size); \
phase_ = Phase::ReadyToPost
/// Handles instructions of the form rr, kk and rr, jjkk, i.e. a destination register plus an operand.
#define RegData(op, dest, size) \
SetOpSrcDestSize(op, DirectAddress, dest, size); \
source_ = Source::Immediate; \
operand_size_ = size; \
phase_ = Phase::DisplacementOrOperand
/// Handles instructions of the form Ax, jjkk where the latter is implicitly an address.
#define RegAddr(op, dest, op_size, addr_size) \
SetOpSrcDestSize(op, DirectAddress, dest, op_size); \
operand_size_ = addr_size; \
phase_ = Phase::DisplacementOrOperand
/// Handles instructions of the form jjkk, Ax where the former is implicitly an address.
#define AddrReg(op, source, op_size, addr_size) \
SetOpSrcDestSize(op, source, DirectAddress, op_size); \
operand_size_ = addr_size; \
destination_ = Source::DirectAddress; \
phase_ = Phase::DisplacementOrOperand
/// Covers both `mem/reg, reg` and `reg, mem/reg`.
#define MemRegReg(op, format, size) \
operation_ = Operation::op; \
phase_ = Phase::ModRegRM; \
modregrm_format_ = ModRegRMFormat::format; \
operand_size_ = DataSize::None; \
operation_size_ = size
/// Handles JO, JNO, JB, etc — jumps with a single byte displacement.
#define Jump(op, size) \
operation_ = Operation::op; \
phase_ = Phase::DisplacementOrOperand; \
displacement_size_ = size
/// Handles far CALL and far JMP — fixed four byte operand operations.
#define Far(op) \
operation_ = Operation::op; \
phase_ = Phase::DisplacementOrOperand; \
operand_size_ = data_size_; \
displacement_size_ = DataSize::Word
/// Handles ENTER — a fixed three-byte operation.
#define Displacement16Operand8(op) \
operation_ = Operation::op; \
phase_ = Phase::DisplacementOrOperand; \
displacement_size_ = DataSize::Word; \
operand_size_ = DataSize::Byte
#define undefined() { \
const auto result = std::make_pair(consumed_, InstructionT()); \
reset_parsing(); \
return result; \
}
#define Requires(x) if constexpr (model != Model::x) undefined();
#define RequiresMin(x) if constexpr (model < Model::x) undefined();
while(phase_ == Phase::Instruction && source != end) {
const uint8_t instr = *source;
++source;
++consumed_;
switch(instr) {
default: undefined();
#define PartialBlock(start, operation) \
case start + 0x00: MemRegReg(operation, MemReg_Reg, DataSize::Byte); break; \
case start + 0x01: MemRegReg(operation, MemReg_Reg, data_size_); break; \
case start + 0x02: MemRegReg(operation, Reg_MemReg, DataSize::Byte); break; \
case start + 0x03: MemRegReg(operation, Reg_MemReg, data_size_); break; \
case start + 0x04: RegData(operation, eAX, DataSize::Byte); break; \
case start + 0x05: RegData(operation, eAX, data_size_)
PartialBlock(0x00, ADD); break;
case 0x06: Complete(PUSH, ES, None, data_size_); break;
case 0x07: Complete(POP, None, ES, data_size_); break;
PartialBlock(0x08, OR); break;
case 0x0e: Complete(PUSH, CS, None, data_size_); break;
// The 286 onwards have a further set of instructions
// prefixed with $0f.
case 0x0f:
RequiresMin(i80286);
phase_ = Phase::InstructionPageF;
break;
PartialBlock(0x10, ADC); break;
case 0x16: Complete(PUSH, SS, None, DataSize::Word); break;
case 0x17: Complete(POP, None, SS, DataSize::Word); break;
PartialBlock(0x18, SBB); break;
case 0x1e: Complete(PUSH, DS, None, DataSize::Word); break;
case 0x1f: Complete(POP, None, DS, DataSize::Word); break;
PartialBlock(0x20, AND); break;
case 0x26: segment_override_ = Source::ES; break;
case 0x27: Complete(DAA, eAX, eAX, DataSize::Byte); break;
PartialBlock(0x28, SUB); break;
case 0x2e: segment_override_ = Source::CS; break;
case 0x2f: Complete(DAS, eAX, eAX, DataSize::Byte); break;
PartialBlock(0x30, XOR); break;
case 0x36: segment_override_ = Source::SS; break;
case 0x37: Complete(AAA, eAX, eAX, DataSize::Word); break;
PartialBlock(0x38, CMP); break;
case 0x3e: segment_override_ = Source::DS; break;
case 0x3f: Complete(AAS, eAX, eAX, DataSize::Word); break;
#undef PartialBlock
#define RegisterBlock(start, operation) \
case start + 0x00: Complete(operation, eAX, eAX, data_size_); break; \
case start + 0x01: Complete(operation, eCX, eCX, data_size_); break; \
case start + 0x02: Complete(operation, eDX, eDX, data_size_); break; \
case start + 0x03: Complete(operation, eBX, eBX, data_size_); break; \
case start + 0x04: Complete(operation, eSP, eSP, data_size_); break; \
case start + 0x05: Complete(operation, eBP, eBP, data_size_); break; \
case start + 0x06: Complete(operation, eSI, eSI, data_size_); break; \
case start + 0x07: Complete(operation, eDI, eDI, data_size_)
RegisterBlock(0x40, INC); break;
RegisterBlock(0x48, DEC); break;
RegisterBlock(0x50, PUSH); break;
RegisterBlock(0x58, POP); break;
#undef RegisterBlock
case 0x60:
RequiresMin(i80186);
Complete(PUSHA, None, None, data_size_);
break;
case 0x61:
RequiresMin(i80186);
Complete(POPA, None, None, data_size_);
break;
case 0x62:
RequiresMin(i80186);
MemRegReg(BOUND, Reg_MemReg, data_size_);
break;
case 0x63:
RequiresMin(i80286);
MemRegReg(ARPL, MemReg_Reg, DataSize::Word);
break;
case 0x66:
RequiresMin(i80386);
data_size_ = DataSize(int(default_data_size_) ^ int(DataSize::Word) ^ int(DataSize::DWord));
break;
case 0x67:
RequiresMin(i80386);
address_size_ = AddressSize(int(default_address_size_) ^ int(AddressSize::b16) ^ int(AddressSize::b32));
break;
case 0x6c: // INSB
RequiresMin(i80186);
Complete(INS, None, None, DataSize::Byte);
break;
case 0x6d: // INSW
RequiresMin(i80186);
Complete(INS, None, None, data_size_);
break;
case 0x6e: // OUTSB
RequiresMin(i80186);
Complete(OUTS, None, None, DataSize::Byte);
break;
case 0x6f: // OUTSW
RequiresMin(i80186);
Complete(OUTS, None, None, data_size_);
break;
case 0x70: Jump(JO, DataSize::Byte); break;
case 0x71: Jump(JNO, DataSize::Byte); break;
case 0x72: Jump(JB, DataSize::Byte); break;
case 0x73: Jump(JNB, DataSize::Byte); break;
case 0x74: Jump(JE, DataSize::Byte); break;
case 0x75: Jump(JNE, DataSize::Byte); break;
case 0x76: Jump(JBE, DataSize::Byte); break;
case 0x77: Jump(JNBE, DataSize::Byte); break;
case 0x78: Jump(JS, DataSize::Byte); break;
case 0x79: Jump(JNS, DataSize::Byte); break;
case 0x7a: Jump(JP, DataSize::Byte); break;
case 0x7b: Jump(JNP, DataSize::Byte); break;
case 0x7c: Jump(JL, DataSize::Byte); break;
case 0x7d: Jump(JNL, DataSize::Byte); break;
case 0x7e: Jump(JLE, DataSize::Byte); break;
case 0x7f: Jump(JNLE, DataSize::Byte); break;
case 0x80: MemRegReg(Invalid, MemRegADD_to_CMP, DataSize::Byte); break;
case 0x81: MemRegReg(Invalid, MemRegADD_to_CMP, data_size_); break;
case 0x82: MemRegReg(Invalid, MemRegADD_to_CMP_SignExtend, DataSize::Byte); break;
case 0x83: MemRegReg(Invalid, MemRegADD_to_CMP_SignExtend, data_size_); break;
case 0x84: MemRegReg(TEST, MemReg_Reg, DataSize::Byte); break;
case 0x85: MemRegReg(TEST, MemReg_Reg, data_size_); break;
case 0x86: MemRegReg(XCHG, Reg_MemReg, DataSize::Byte); break;
case 0x87: MemRegReg(XCHG, Reg_MemReg, data_size_); break;
case 0x88: MemRegReg(MOV, MemReg_Reg, DataSize::Byte); break;
case 0x89: MemRegReg(MOV, MemReg_Reg, data_size_); break;
case 0x8a: MemRegReg(MOV, Reg_MemReg, DataSize::Byte); break;
case 0x8b: MemRegReg(MOV, Reg_MemReg, data_size_); break;
// 0x8c: not used.
case 0x8d: MemRegReg(LEA, Reg_MemReg, data_size_); break;
case 0x8e: MemRegReg(MOV, SegReg, data_size_); break;
case 0x8f: MemRegReg(POP, MemRegPOP, data_size_); break;
case 0x90: Complete(NOP, None, None, DataSize::None); break; // Or XCHG AX, AX?
case 0x91: Complete(XCHG, eAX, eCX, data_size_); break;
case 0x92: Complete(XCHG, eAX, eDX, data_size_); break;
case 0x93: Complete(XCHG, eAX, eBX, data_size_); break;
case 0x94: Complete(XCHG, eAX, eSP, data_size_); break;
case 0x95: Complete(XCHG, eAX, eBP, data_size_); break;
case 0x96: Complete(XCHG, eAX, eSI, data_size_); break;
case 0x97: Complete(XCHG, eAX, eDI, data_size_); break;
case 0x98: Complete(CBW, eAX, AH, DataSize::Byte); break;
case 0x99: Complete(CWD, eAX, eDX, data_size_); break;
case 0x9a: Far(CALLF); break;
case 0x9b: Complete(WAIT, None, None, DataSize::None); break;
case 0x9c: Complete(PUSHF, None, None, data_size_); break;
case 0x9d: Complete(POPF, None, None, data_size_); break;
case 0x9e: Complete(SAHF, None, None, DataSize::Byte); break;
case 0x9f: Complete(LAHF, None, None, DataSize::Byte); break;
case 0xa0: RegAddr(MOV, eAX, DataSize::Byte, DataSize::Byte); break;
case 0xa1: RegAddr(MOV, eAX, data_size_, data_size_); break;
case 0xa2: AddrReg(MOV, eAX, DataSize::Byte, DataSize::Byte); break;
case 0xa3: AddrReg(MOV, eAX, data_size_, data_size_); break;
case 0xa4: Complete(MOVS, None, None, DataSize::Byte); break;
case 0xa5: Complete(MOVS, None, None, data_size_); break;
case 0xa6: Complete(CMPS, None, None, DataSize::Byte); break;
case 0xa7: Complete(CMPS, None, None, data_size_); break;
case 0xa8: RegData(TEST, eAX, DataSize::Byte); break;
case 0xa9: RegData(TEST, eAX, data_size_); break;
case 0xaa: Complete(STOS, None, None, DataSize::Byte); break;
case 0xab: Complete(STOS, None, None, data_size_); break;
case 0xac: Complete(LODS, None, None, DataSize::Byte); break;
case 0xad: Complete(LODS, None, None, data_size_); break;
case 0xae: Complete(SCAS, None, None, DataSize::Byte); break;
case 0xaf: Complete(SCAS, None, None, data_size_); break;
case 0xb0: RegData(MOV, eAX, DataSize::Byte); break;
case 0xb1: RegData(MOV, eCX, DataSize::Byte); break;
case 0xb2: RegData(MOV, eDX, DataSize::Byte); break;
case 0xb3: RegData(MOV, eBX, DataSize::Byte); break;
case 0xb4: RegData(MOV, AH, DataSize::Byte); break;
case 0xb5: RegData(MOV, CH, DataSize::Byte); break;
case 0xb6: RegData(MOV, DH, DataSize::Byte); break;
case 0xb7: RegData(MOV, BH, DataSize::Byte); break;
case 0xb8: RegData(MOV, eAX, data_size_); break;
case 0xb9: RegData(MOV, eCX, data_size_); break;
case 0xba: RegData(MOV, eDX, data_size_); break;
case 0xbb: RegData(MOV, eBX, data_size_); break;
case 0xbc: RegData(MOV, eSP, data_size_); break;
case 0xbd: RegData(MOV, eBP, data_size_); break;
case 0xbe: RegData(MOV, eSI, data_size_); break;
case 0xbf: RegData(MOV, eDI, data_size_); break;
case 0xc2: RegData(RETN, None, data_size_); break;
case 0xc3: Complete(RETN, None, None, DataSize::None); break;
case 0xc4: MemRegReg(LES, Reg_MemReg, data_size_); break;
case 0xc5: MemRegReg(LDS, Reg_MemReg, data_size_); break;
case 0xc6: MemRegReg(MOV, MemRegMOV, DataSize::Byte); break;
case 0xc7: MemRegReg(MOV, MemRegMOV, data_size_); break;
case 0xc8:
RequiresMin(i80186);
Displacement16Operand8(ENTER);
break;
case 0xc9:
RequiresMin(i80186);
Complete(LEAVE, None, None, DataSize::None);
break;
case 0xca: RegData(RETF, None, data_size_); break;
case 0xcb: Complete(RETF, None, None, DataSize::DWord); break;
case 0xcc: Complete(INT3, None, None, DataSize::None); break;
case 0xcd: RegData(INT, None, DataSize::Byte); break;
case 0xce: Complete(INTO, None, None, DataSize::None); break;
case 0xcf: Complete(IRET, None, None, DataSize::None); break;
case 0xd0: case 0xd1: {
const DataSize sizes[] = {DataSize::Byte, data_size_};
phase_ = Phase::ModRegRM;
modregrm_format_ = ModRegRMFormat::MemRegROL_to_SAR;
operation_size_ = sizes[instr & 1];
source_ = Source::Immediate;
operand_ = 1;
} break;
case 0xd2: case 0xd3: {
const DataSize sizes[] = {DataSize::Byte, data_size_};
phase_ = Phase::ModRegRM;
modregrm_format_ = ModRegRMFormat::MemRegROL_to_SAR;
operation_size_ = sizes[instr & 1];
source_ = Source::eCX;
} break;
case 0xd4: RegData(AAM, eAX, DataSize::Byte); break;
case 0xd5: RegData(AAD, eAX, DataSize::Byte); break;
case 0xd7: Complete(XLAT, None, None, DataSize::Byte); break;
case 0xd8: MemRegReg(ESC, MemReg_Reg, DataSize::None); break;
case 0xd9: MemRegReg(ESC, MemReg_Reg, DataSize::None); break;
case 0xda: MemRegReg(ESC, MemReg_Reg, DataSize::None); break;
case 0xdb: MemRegReg(ESC, MemReg_Reg, DataSize::None); break;
case 0xdc: MemRegReg(ESC, MemReg_Reg, DataSize::None); break;
case 0xdd: MemRegReg(ESC, MemReg_Reg, DataSize::None); break;
case 0xde: MemRegReg(ESC, MemReg_Reg, DataSize::None); break;
case 0xdf: MemRegReg(ESC, MemReg_Reg, DataSize::None); break;
case 0xe0: Jump(LOOPNE, DataSize::Byte); break;
case 0xe1: Jump(LOOPE, DataSize::Byte); break;
case 0xe2: Jump(LOOP, DataSize::Byte); break;
case 0xe3: Jump(JPCX, DataSize::Byte); break;
case 0xe4: RegAddr(IN, eAX, DataSize::Byte, DataSize::Byte); break;
case 0xe5: RegAddr(IN, eAX, data_size_, DataSize::Byte); break;
case 0xe6: AddrReg(OUT, eAX, DataSize::Byte, DataSize::Byte); break;
case 0xe7: AddrReg(OUT, eAX, data_size_, DataSize::Byte); break;
case 0xe8: RegData(CALLD, None, data_size_); break;
case 0xe9: RegData(JMPN, None, data_size_); break;
case 0xea: Far(JMPF); break;
case 0xeb: Jump(JMPN, DataSize::Byte); break;
case 0xec: Complete(IN, eDX, eAX, DataSize::Byte); break;
case 0xed: Complete(IN, eDX, eAX, data_size_); break;
case 0xee: Complete(OUT, eAX, eDX, DataSize::Byte); break;
case 0xef: Complete(OUT, eAX, eDX, data_size_); break;
case 0xf0: lock_ = true; break;
case 0xf2: repetition_ = Repetition::RepNE; break;
case 0xf3: repetition_ = Repetition::RepE; break;
case 0xf4: Complete(HLT, None, None, DataSize::None); break;
case 0xf5: Complete(CMC, None, None, DataSize::None); break;
case 0xf6: MemRegReg(Invalid, MemRegTEST_to_IDIV, DataSize::Byte); break;
case 0xf7: MemRegReg(Invalid, MemRegTEST_to_IDIV, data_size_); break;
case 0xf8: Complete(CLC, None, None, DataSize::None); break;
case 0xf9: Complete(STC, None, None, DataSize::None); break;
case 0xfa: Complete(CLI, None, None, DataSize::None); break;
case 0xfb: Complete(STI, None, None, DataSize::None); break;
case 0xfc: Complete(CLD, None, None, DataSize::None); break;
case 0xfd: Complete(STD, None, None, DataSize::None); break;
case 0xfe: MemRegReg(Invalid, MemRegINC_DEC, DataSize::Byte); break;
case 0xff: MemRegReg(Invalid, MemRegINC_to_PUSH, data_size_); break;
}
}
// MARK: - Additional F page of instructions.
if(phase_ == Phase::InstructionPageF && source != end) {
// Update the instruction acquired.
const uint8_t instr = *source;
++source;
++consumed_;
// NB: to reach here, the instruction set must be at least
// that of an 80286.
switch(instr) {
default: undefined();
case 0x00: MemRegReg(Invalid, MemRegSLDT_to_VERW, data_size_); break;
case 0x01: MemRegReg(Invalid, MemRegSGDT_to_LMSW, data_size_); break;
case 0x02: MemRegReg(LAR, Reg_MemReg, data_size_); break;
case 0x03: MemRegReg(LSL, Reg_MemReg, data_size_); break;
case 0x05:
Requires(i80286);
Complete(LOADALL, None, None, DataSize::None);
break;
case 0x06: Complete(CLTS, None, None, DataSize::Byte); break;
}
}
#undef Requires
#undef RequiresMin
#undef Far
#undef Jump
#undef MemRegReg
#undef AddrReg
#undef RegAddr
#undef RegData
#undef Complete
#undef SetOpSrcDestSize
// MARK: - ModRegRM byte, if any.
if(phase_ == Phase::ModRegRM && source != end) {
const uint8_t mod = *source >> 6; // i.e. mode.
const uint8_t reg = (*source >> 3) & 7; // i.e. register.
const uint8_t rm = *source & 7; // i.e. register/memory.
++source;
++consumed_;
Source memreg;
constexpr Source reg_table[8] = {
Source::eAX, Source::eCX, Source::eDX, Source::eBX,
Source::eSPorAH, Source::eBPorCH, Source::eSIorDH, Source::eDIorBH,
};
switch(mod) {
default: {
const DataSize sizes[] = {DataSize::Byte, data_size_};
displacement_size_ = sizes[mod == 2];
}
[[fallthrough]];
case 0: {
constexpr ScaleIndexBase rm_table[8] = {
ScaleIndexBase(0, Source::eBX, Source::eSI),
ScaleIndexBase(0, Source::eBX, Source::eDI),
ScaleIndexBase(0, Source::eBP, Source::eSI),
ScaleIndexBase(0, Source::eBP, Source::eDI),
ScaleIndexBase(0, Source::None, Source::eSI),
ScaleIndexBase(0, Source::None, Source::eDI),
ScaleIndexBase(0, Source::None, Source::eBP),
ScaleIndexBase(0, Source::None, Source::eBX),
};
memreg = Source::Indirect;
sib_ = rm_table[rm];
} break;
// Other operand is just a register.
case 3:
memreg = reg_table[rm];
// LES and LDS accept a memory argument only, not a register.
if(operation_ == Operation::LES || operation_ == Operation::LDS) {
undefined();
}
break;
}
switch(modregrm_format_) {
case ModRegRMFormat::Reg_MemReg:
case ModRegRMFormat::MemReg_Reg: {
if(modregrm_format_ == ModRegRMFormat::Reg_MemReg) {
source_ = memreg;
destination_ = reg_table[reg];
} else {
source_ = reg_table[reg];
destination_ = memreg;
}
} break;
case ModRegRMFormat::MemRegTEST_to_IDIV:
source_ = destination_ = memreg;
switch(reg) {
default: undefined();
case 0: operation_ = Operation::TEST; break;
case 2: operation_ = Operation::NOT; break;
case 3: operation_ = Operation::NEG; break;
case 4: operation_ = Operation::MUL; break;
case 5: operation_ = Operation::IMUL; break;
case 6: operation_ = Operation::DIV; break;
case 7: operation_ = Operation::IDIV; break;
}
break;
case ModRegRMFormat::SegReg: {
source_ = memreg;
constexpr Source seg_table[4] = {
Source::ES, Source::CS,
Source::SS, Source::DS,
};
if(reg & 4) {
undefined();
}
destination_ = seg_table[reg];
} break;
case ModRegRMFormat::MemRegROL_to_SAR:
destination_ = memreg;
switch(reg) {
default: undefined();
case 0: operation_ = Operation::ROL; break;
case 2: operation_ = Operation::ROR; break;
case 3: operation_ = Operation::RCL; break;
case 4: operation_ = Operation::RCR; break;
case 5: operation_ = Operation::SAL; break;
case 6: operation_ = Operation::SHR; break;
case 7: operation_ = Operation::SAR; break;
}
break;
case ModRegRMFormat::MemRegINC_DEC:
source_ = destination_ = memreg;
switch(reg) {
default: undefined();
case 0: operation_ = Operation::INC; break;
case 1: operation_ = Operation::DEC; break;
}
break;
case ModRegRMFormat::MemRegINC_to_PUSH:
source_ = destination_ = memreg;
switch(reg) {
default: undefined();
case 0: operation_ = Operation::INC; break;
case 1: operation_ = Operation::DEC; break;
case 2: operation_ = Operation::CALLN; break;
case 3:
operation_ = Operation::CALLF;
operand_size_ = DataSize::DWord;
source_ = Source::Immediate;
break;
case 4: operation_ = Operation::JMPN; break;
case 5:
operation_ = Operation::JMPF;
operand_size_ = DataSize::DWord;
source_ = Source::Immediate;
break;
case 6: operation_ = Operation::PUSH; break;
}
break;
case ModRegRMFormat::MemRegPOP:
source_ = destination_ = memreg;
if(reg != 0) {
undefined();
}
break;
case ModRegRMFormat::MemRegMOV:
source_ = Source::Immediate;
destination_ = memreg;
operand_size_ = operation_size_;
break;
case ModRegRMFormat::MemRegADD_to_CMP:
case ModRegRMFormat::MemRegADD_to_CMP_SignExtend:
source_ = Source::Immediate;
destination_ = memreg;
operand_size_ = (modregrm_format_ == ModRegRMFormat::MemRegADD_to_CMP_SignExtend) ? DataSize::Byte : operation_size_;
sign_extend_ = true; // Will be effective only if modregrm_format_ == ModRegRMFormat::MemRegADD_to_CMP_SignExtend.
switch(reg) {
default: operation_ = Operation::ADD; break;
case 1: operation_ = Operation::OR; break;
case 2: operation_ = Operation::ADC; break;
case 3: operation_ = Operation::SBB; break;
case 4: operation_ = Operation::AND; break;
case 5: operation_ = Operation::SUB; break;
case 6: operation_ = Operation::XOR; break;
case 7: operation_ = Operation::CMP; break;
}
break;
case ModRegRMFormat::MemRegSLDT_to_VERW:
destination_ = source_ = memreg;
switch(reg) {
default: undefined();
case 0: operation_ = Operation::SLDT; break;
case 1: operation_ = Operation::STR; break;
case 2: operation_ = Operation::LLDT; break;
case 3: operation_ = Operation::LTR; break;
case 4: operation_ = Operation::VERR; break;
case 5: operation_ = Operation::VERW; break;
}
break;
case ModRegRMFormat::MemRegSGDT_to_LMSW:
destination_ = source_ = memreg;
switch(reg) {
default: undefined();
case 0: operation_ = Operation::SGDT; break;
case 2: operation_ = Operation::LGDT; break;
case 4: operation_ = Operation::SMSW; break;
case 6: operation_ = Operation::LMSW; break;
}
break;
default: assert(false);
}
phase_ = (displacement_size_ != DataSize::None || operand_size_ != DataSize::None) ? Phase::DisplacementOrOperand : Phase::ReadyToPost;
}
#undef undefined
// MARK: - ScaleIndexBase
if(phase_ == Phase::ScaleIndexBase && source != end) {
sib_ = *source;
++source;
++consumed_;
}
// MARK: - Displacement and operand.
if(phase_ == Phase::DisplacementOrOperand && source != end) {
const auto required_bytes = int(byte_size(displacement_size_) + byte_size(operand_size_));
const int outstanding_bytes = required_bytes - operand_bytes_;
const int bytes_to_consume = std::min(int(end - source), outstanding_bytes);
for(int c = 0; c < bytes_to_consume; c++) {
inward_data_ |= decltype(inward_data_)(source[0]) << next_inward_data_shift_;
++source;
next_inward_data_shift_ += 8;
}
consumed_ += bytes_to_consume;
operand_bytes_ += bytes_to_consume;
if(bytes_to_consume == outstanding_bytes) {
phase_ = Phase::ReadyToPost;
switch(displacement_size_) {
case DataSize::None: displacement_ = 0; break;
case DataSize::Byte: displacement_ = int8_t(inward_data_); break;
case DataSize::Word: displacement_ = int16_t(inward_data_); break;
case DataSize::DWord: displacement_ = int32_t(inward_data_); break;
}
inward_data_ >>= bit_size(displacement_size_);
// Use inequality of sizes as a test for necessary sign extension.
if(operand_size_ == data_size_ || !sign_extend_) {
operand_ = decltype(operand_)(inward_data_);
} else {
switch(operand_size_) {
case DataSize::None: operand_ = 0; break;
case DataSize::Byte: operand_ = decltype(operand_)(int8_t(inward_data_)); break;
case DataSize::Word: operand_ = decltype(operand_)(int16_t(inward_data_)); break;
case DataSize::DWord: operand_ = decltype(operand_)(int32_t(inward_data_)); break;
}
}
// TODO: split differently for far jumps/etc. But that information is
// no longer retained now that it's not implied by a DWord-sized operand.
} else {
// Provide a genuine measure of further bytes required.
return std::make_pair(-(outstanding_bytes - bytes_to_consume), InstructionT());
}
}
// MARK: - Check for completion.
if(phase_ == Phase::ReadyToPost) {
const auto result = std::make_pair(
consumed_,
InstructionT(
operation_,
source_,
destination_,
sib_,
lock_,
address_size_,
segment_override_,
repetition_,
DataSize(operation_size_),
static_cast<typename InstructionT::DisplacementT>(displacement_),
static_cast<typename InstructionT::ImmediateT>(operand_))
);
reset_parsing();
return result;
}
// i.e. not done yet.
return std::make_pair(0, InstructionT());
}
template <Model model> void Decoder<model>::set_32bit_protected_mode(bool enabled) {
if constexpr (!is_32bit(model)) {
assert(!enabled);
return;
}
if(enabled) {
default_address_size_ = address_size_ = AddressSize::b32;
default_data_size_ = data_size_ = DataSize::DWord;
} else {
default_address_size_ = address_size_ = AddressSize::b16;
default_data_size_ = data_size_ = DataSize::Word;
}
}
// Ensure all possible decoders are built.
template class InstructionSet::x86::Decoder<InstructionSet::x86::Model::i8086>;
template class InstructionSet::x86::Decoder<InstructionSet::x86::Model::i80186>;
template class InstructionSet::x86::Decoder<InstructionSet::x86::Model::i80286>;
template class InstructionSet::x86::Decoder<InstructionSet::x86::Model::i80386>;
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