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CLK/InstructionSets/x86/Decoder.cpp
Thomas Harte 1725894fe9 Eliminate redundant CMPSD, CDQ, CWDE. 
Also removes IBTS for now, as I'm unclear where it should sit in the opcode map.
2022-03-12 12:24:44 -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) {
// Instruction length limits:
//
// 8086/80186: none*
// 80286: 10 bytes
// 80386: 15 bytes
//
// * but, can treat internally as a limit of 65536 bytes — after that distance the IP will
// be back to wherever it started, so it's safe to spit out a NOP and reset parsing
// without any loss of context. This reduces the risk of the decoder tricking a caller into
// an infinite loop.
constexpr int max_instruction_length = model >= Model::i80386 ? 15 : (model == Model::i80286 ? 10 : 65536);
const uint8_t *const end = source + std::min(length, size_t(max_instruction_length - consumed_));
// 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 — anything with only a displacement.
#define Displacement(op, size) \
operation_ = Operation::op; \
phase_ = Phase::DisplacementOrOperand; \
displacement_size_ = size
/// Handles PUSH [immediate], etc — anything with only an immediate operand.
#define Immediate(op, size) \
operation_ = Operation::op; \
source_ = Source::Immediate; \
phase_ = Phase::DisplacementOrOperand; \
operand_size_ = size
/// Handles far CALL and far JMP — fixed four or six byte operand operations.
#define Far(op) \
operation_ = Operation::op; \
phase_ = Phase::DisplacementOrOperand; \
operand_size_ = DataSize::Word; \
displacement_size_ = data_size(default_address_size_)
/// Handles ENTER — a fixed three-byte operation.
#define Displacement16Operand8(op) \
operation_ = Operation::op; \
phase_ = Phase::DisplacementOrOperand; \
displacement_size_ = DataSize::Word; \
operand_size_ = DataSize::Byte
/// Sets up the operation size, oncoming phase and modregrm format for a member of the shift group (i.e. 'group 2').
#define ShiftGroup() { \
const DataSize sizes[] = {DataSize::Byte, data_size_}; \
phase_ = Phase::ModRegRM; \
modregrm_format_ = ModRegRMFormat::MemRegROL_to_SAR; \
operation_size_ = sizes[instr & 1]; \
}
#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 0x64:
RequiresMin(i80386);
segment_override_ = Source::FS;
break;
case 0x65:
RequiresMin(i80386);
segment_override_ = Source::GS;
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 0x68:
RequiresMin(i80286);
Immediate(PUSH, data_size_);
operation_size_ = data_size_;
break;
case 0x69:
RequiresMin(i80286);
MemRegReg(IMUL_3, Reg_MemReg, data_size_);
operand_size_ = data_size_;
break;
case 0x6a:
RequiresMin(i80286);
Immediate(PUSH, DataSize::Byte);
break;
case 0x6b:
RequiresMin(i80286);
MemRegReg(IMUL_3, Reg_MemReg, data_size_);
operand_size_ = DataSize::Byte;
sign_extend_ = true;
break;
case 0x6c: // INSB
RequiresMin(i80186);
Complete(INS, None, None, DataSize::Byte);
break;
case 0x6d: // INSW/INSD
RequiresMin(i80186);
Complete(INS, None, None, data_size_);
break;
case 0x6e: // OUTSB
RequiresMin(i80186);
Complete(OUTS, None, None, DataSize::Byte);
break;
case 0x6f: // OUTSW/OUSD
RequiresMin(i80186);
Complete(OUTS, None, None, data_size_);
break;
case 0x70: Displacement(JO, DataSize::Byte); break;
case 0x71: Displacement(JNO, DataSize::Byte); break;
case 0x72: Displacement(JB, DataSize::Byte); break;
case 0x73: Displacement(JNB, DataSize::Byte); break;
case 0x74: Displacement(JE, DataSize::Byte); break;
case 0x75: Displacement(JNE, DataSize::Byte); break;
case 0x76: Displacement(JBE, DataSize::Byte); break;
case 0x77: Displacement(JNBE, DataSize::Byte); break;
case 0x78: Displacement(JS, DataSize::Byte); break;
case 0x79: Displacement(JNS, DataSize::Byte); break;
case 0x7a: Displacement(JP, DataSize::Byte); break;
case 0x7b: Displacement(JNP, DataSize::Byte); break;
case 0x7c: Displacement(JL, DataSize::Byte); break;
case 0x7d: Displacement(JNL, DataSize::Byte); break;
case 0x7e: Displacement(JLE, DataSize::Byte); break;
case 0x7f: Displacement(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;
case 0x8c: MemRegReg(MOV, MemReg_Seg, DataSize::Word); break;
case 0x8d: MemRegReg(LEA, Reg_MemReg, data_size_); break;
case 0x8e: MemRegReg(MOV, Seg_MemReg, DataSize::Word); break;
case 0x8f: MemRegReg(POP, MemRegSingleOperand, 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, data_size_); break;
case 0x99: Complete(CWD, eAX, eDX, data_size_); break;
case 0x9a: Far(CALLfar); 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, data_size(address_size_)); break;
case 0xa1: RegAddr(MOV, eAX, data_size_, data_size(address_size_)); break;
case 0xa2: AddrReg(MOV, eAX, DataSize::Byte, data_size(address_size_)); break;
case 0xa3: AddrReg(MOV, eAX, data_size_, data_size(address_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 0xc0: case 0xc1:
RequiresMin(i80186);
ShiftGroup();
source_ = Source::Immediate;
operand_size_ = DataSize::Byte;
break;
case 0xc2: RegData(RETnear, None, data_size_); break;
case 0xc3: Complete(RETnear, 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(RETfar, None, data_size_); break;
case 0xcb: Complete(RETfar, None, None, DataSize::DWord); break;
case 0xcc:
// Encode INT3 as though it were INT with an
// immediate operand of 3.
Complete(INT, Immediate, None, DataSize::Byte);
operand_ = 3;
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:
ShiftGroup();
source_ = Source::Immediate;
operand_ = 1;
break;
case 0xd2: case 0xd3:
ShiftGroup();
source_ = Source::eCX;
break;
case 0xd4: RegData(AAM, eAX, DataSize::Byte); break;
case 0xd5: RegData(AAD, eAX, DataSize::Byte); break;
// Unused: 0xd6.
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: Displacement(LOOPNE, DataSize::Byte); break;
case 0xe1: Displacement(LOOPE, DataSize::Byte); break;
case 0xe2: Displacement(LOOP, DataSize::Byte); break;
case 0xe3: Displacement(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: Displacement(CALLrel, data_size_); break;
case 0xe9: Displacement(JMPrel, data_size_); break;
case 0xea: Far(JMPfar); break;
case 0xeb: Displacement(JMPrel, 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;
// Unused: 0xf1
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;
case 0x20:
RequiresMin(i80386);
MemRegReg(MOVfromCr, Reg_MemReg, DataSize::DWord);
break;
case 0x21:
RequiresMin(i80386);
MemRegReg(MOVfromDr, Reg_MemReg, DataSize::DWord);
break;
case 0x22:
RequiresMin(i80386);
MemRegReg(MOVtoCr, Reg_MemReg, DataSize::DWord);
break;
case 0x23:
RequiresMin(i80386);
MemRegReg(MOVtoDr, Reg_MemReg, DataSize::DWord);
break;
case 0x24:
RequiresMin(i80386);
MemRegReg(MOVfromTr, Reg_MemReg, DataSize::DWord);
break;
case 0x26:
RequiresMin(i80386);
MemRegReg(MOVtoTr, Reg_MemReg, DataSize::DWord);
break;
case 0x70: RequiresMin(i80386); Displacement(JO, data_size_); break;
case 0x71: RequiresMin(i80386); Displacement(JNO, data_size_); break;
case 0x72: RequiresMin(i80386); Displacement(JB, data_size_); break;
case 0x73: RequiresMin(i80386); Displacement(JNB, data_size_); break;
case 0x74: RequiresMin(i80386); Displacement(JE, data_size_); break;
case 0x75: RequiresMin(i80386); Displacement(JNE, data_size_); break;
case 0x76: RequiresMin(i80386); Displacement(JBE, data_size_); break;
case 0x77: RequiresMin(i80386); Displacement(JNBE, data_size_); break;
case 0x78: RequiresMin(i80386); Displacement(JS, data_size_); break;
case 0x79: RequiresMin(i80386); Displacement(JNS, data_size_); break;
case 0x7a: RequiresMin(i80386); Displacement(JP, data_size_); break;
case 0x7b: RequiresMin(i80386); Displacement(JNP, data_size_); break;
case 0x7c: RequiresMin(i80386); Displacement(JL, data_size_); break;
case 0x7d: RequiresMin(i80386); Displacement(JNL, data_size_); break;
case 0x7e: RequiresMin(i80386); Displacement(JLE, data_size_); break;
case 0x7f: RequiresMin(i80386); Displacement(JNLE, data_size_); break;
#define Set(x) \
RequiresMin(i80386); \
MemRegReg(SET##x, MemRegSingleOperand, DataSize::Byte);
case 0x90: Set(O); break;
case 0x91: Set(NO); break;
case 0x92: Set(B); break;
case 0x93: Set(NB); break;
case 0x94: Set(Z); break;
case 0x95: Set(NZ); break;
case 0x96: Set(BE); break;
case 0x97: Set(NBE); break;
case 0x98: Set(S); break;
case 0x99: Set(NS); break;
case 0x9a: Set(P); break;
case 0x9b: Set(NP); break;
case 0x9c: Set(L); break;
case 0x9d: Set(NL); break;
case 0x9e: Set(LE); break;
case 0x9f: Set(NLE); break;
#undef Set
case 0xa0: RequiresMin(i80386); Complete(PUSH, FS, None, data_size_); break;
case 0xa1: RequiresMin(i80386); Complete(POP, FS, None, data_size_); break;
case 0xa3: RequiresMin(i80386); MemRegReg(BT, MemReg_Reg, data_size_); break;
case 0xa4:
RequiresMin(i80386);
MemRegReg(SHLDimm, Reg_MemReg, data_size_);
operand_size_ = DataSize::Byte;
break;
case 0xa5:
RequiresMin(i80386);
MemRegReg(SHLDCL, MemReg_Reg, data_size_);
break;
case 0xa8: RequiresMin(i80386); Complete(PUSH, GS, None, data_size_); break;
case 0xa9: RequiresMin(i80386); Complete(POP, GS, None, data_size_); break;
case 0xab: RequiresMin(i80386); MemRegReg(BTS, MemReg_Reg, data_size_); break;
case 0xac:
RequiresMin(i80386);
MemRegReg(SHRDimm, Reg_MemReg, data_size_);
operand_size_ = DataSize::Byte;
break;
case 0xad:
RequiresMin(i80386);
MemRegReg(SHRDCL, MemReg_Reg, data_size_);
break;
case 0xaf:
RequiresMin(i80386);
MemRegReg(IMUL_2, Reg_MemReg, data_size_);
break;
case 0xb2: RequiresMin(i80386); MemRegReg(LSS, Reg_MemReg, data_size_); break;
case 0xb3: RequiresMin(i80386); MemRegReg(BTR, MemReg_Reg, data_size_); break;
case 0xb4: RequiresMin(i80386); MemRegReg(LFS, Reg_MemReg, data_size_); break;
case 0xb5: RequiresMin(i80386); MemRegReg(LGS, Reg_MemReg, data_size_); break;
case 0xb6:
RequiresMin(i80386);
MemRegReg(MOVZX, Reg_MemReg, DataSize::Byte);
break;
case 0xb7:
RequiresMin(i80386);
MemRegReg(MOVZX, Reg_MemReg, DataSize::Word);
break;
case 0xba: RequiresMin(i80386); MemRegReg(Invalid, MemRegBT_to_BTC, data_size_); break;
case 0xbb: RequiresMin(i80386); MemRegReg(BTC, MemReg_Reg, data_size_); break;
case 0xbc: RequiresMin(i80386); MemRegReg(BSF, MemReg_Reg, data_size_); break;
case 0xbd: RequiresMin(i80386); MemRegReg(BSR, MemReg_Reg, data_size_); break;
case 0xbe:
RequiresMin(i80386);
MemRegReg(MOVSX, Reg_MemReg, DataSize::Byte);
break;
case 0xbf:
RequiresMin(i80386);
MemRegReg(MOVSX, Reg_MemReg, DataSize::Word);
break;
}
}
#undef Requires
#undef RequiresMin
#undef ShiftGroup
#undef Displacement16Operand8
#undef Far
#undef Immediate
#undef Displacement
#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.
bool expects_sib = false;
++source;
++consumed_;
Source memreg;
// These tables are fairly redundant due to the register ordering within
// Source, but act to improve readability and permit further Source
// reordering in the future.
constexpr Source reg_table[8] = {
Source::eAX, Source::eCX, Source::eDX, Source::eBX,
Source::eSPorAH, Source::eBPorCH, Source::eSIorDH, Source::eDIorBH,
};
constexpr Source seg_table[6] = {
Source::ES, Source::CS, Source::SS, Source::DS, Source::FS, Source::GS
};
// Mode 3 is the same regardless of 16/32-bit mode. So deal with that up front.
if(mod == 3) {
// Other operand is just a register.
memreg = reg_table[rm];
// LES, LDS, etc accept a memory argument only, not a register.
if(
operation_ == Operation::LES ||
operation_ == Operation::LDS ||
operation_ == Operation::LGS ||
operation_ == Operation::LSS ||
operation_ == Operation::LFS) {
undefined();
}
} else {
const DataSize sizes[] = {
DataSize::None,
DataSize::Byte,
data_size(address_size_)
};
displacement_size_ = sizes[mod];
memreg = Source::Indirect;
if(address_size_ == AddressSize::b32) {
// 32-bit decoding: the range of potential indirections is expanded,
// and may segue into obtaining a SIB.
sib_ = ScaleIndexBase(0, Source::None, reg_table[rm]);
expects_sib = rm == 4; // Indirect via eSP isn't directly supported; it's the
// escape indicator for reading a SIB.
} else {
// Classic 16-bit decoding: mode picks a displacement size,
// and a few fixed index+base pairs are defined.
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),
};
sib_ = rm_table[rm];
}
}
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_1; break;
case 6: operation_ = Operation::DIV; break;
case 7: operation_ = Operation::IDIV; break;
}
break;
case ModRegRMFormat::Seg_MemReg:
case ModRegRMFormat::MemReg_Seg:
// The 16-bit chips have four segment registers;
// the 80386 onwards has six.
if(!is_32bit(model) && reg > 3) {
undefined();
} else if(reg > 5) {
undefined();
}
if(modregrm_format_ == ModRegRMFormat::Seg_MemReg) {
source_ = memreg;
destination_ = seg_table[reg];
// 80286 and later disallow MOV to CS.
if(model >= Model::i80286 && destination_ == Source::CS) {
undefined();
}
} else {
source_ = seg_table[reg];
destination_ = memreg;
}
break;
case ModRegRMFormat::MemRegROL_to_SAR:
destination_ = memreg;
switch(reg) {
default: undefined();
case 0: operation_ = Operation::ROL; break;
case 1: operation_ = Operation::ROR; break;
case 2: operation_ = Operation::RCL; break;
case 3: operation_ = Operation::RCR; break;
case 4: operation_ = Operation::SAL; break;
case 5: 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::CALLabs; break;
case 3: operation_ = Operation::CALLfar; break;
case 4: operation_ = Operation::JMPabs; break;
case 5: operation_ = Operation::JMPfar; break;
case 6: operation_ = Operation::PUSH; break;
}
break;
case ModRegRMFormat::MemRegSingleOperand:
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 1: operation_ = Operation::SIDT; break;
case 2: operation_ = Operation::LGDT; break;
case 3: operation_ = Operation::LIDT; break;
case 4: operation_ = Operation::SMSW; break;
case 6: operation_ = Operation::LMSW; break;
}
break;
case ModRegRMFormat::MemRegBT_to_BTC:
destination_ = memreg;
source_ = Source::Immediate;
operand_size_ = DataSize::Byte;
switch(reg) {
default: undefined();
case 4: operation_ = Operation::BT; break;
case 5: operation_ = Operation::BTS; break;
case 6: operation_ = Operation::BTR; break;
case 7: operation_ = Operation::BTC; break;
}
break;
default: assert(false);
}
if(expects_sib && (source_ == Source::Indirect | destination_ == Source::Indirect)) {
phase_ = Phase::ScaleIndexBase;
} else {
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_;
// Potentially record the lack of a base.
if(displacement_size_ == DataSize::None && (uint8_t(sib_)&7) == 5) {
source_ = (source_ == Source::Indirect) ? Source::IndirectNoBase : source_;
destination_ = (destination_ == Source::Indirect) ? Source::IndirectNoBase : destination_;
}
phase_ = (displacement_size_ != DataSize::None || operand_size_ != DataSize::None) ? Phase::DisplacementOrOperand : Phase::ReadyToPost;
}
// MARK: - Displacement and operand.
if(phase_ == Phase::DisplacementOrOperand) {
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;
}
}
} 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_),
consumed_
)
);
reset_parsing();
return result;
}
// Check for a too-long instruction.
if(consumed_ == max_instruction_length) {
std::pair<int, InstructionT> result;
if(max_instruction_length == 65536) {
result = std::make_pair(consumed_, InstructionT(Operation::NOP, consumed_));
} else {
result = std::make_pair(consumed_, InstructionT());
}
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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