Method LODSOp

FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp:3405–3486

}

void OpDispatchBuilder::LODSOp(OpcodeArgs) {
  if (Op->Flags & FEXCore::X86Tables::DecodeFlags::FLAG_ADDRESS_SIZE) {
    LogMan::Msg::EFmt("Can't handle adddress size");
    DecodeFailure = true;
    return;
  }

  const auto Size = OpSizeFromSrc(Op);
  const bool Repeat = (Op->Flags & (FEXCore::X86Tables::DecodeFlags::FLAG_REP_PREFIX | FEXCore::X86Tables::DecodeFlags::FLAG_REPNE_PREFIX)) != 0;

  if (!Repeat) {
    Ref Dest_RSI = MakeSegmentAddress(X86State::REG_RSI, Op->Flags, X86Tables::DecodeFlags::FLAG_DS_PREFIX);

    auto Src = _LoadMemAutoTSO(GPRClass, Size, Dest_RSI, Size);

    StoreResult(GPRClass, Op, Src, OpSize::iInvalid);

    // Offset the pointer
    Ref TailDest_RSI = LoadGPRRegister(X86State::REG_RSI);
    StoreGPRRegister(X86State::REG_RSI, OffsetByDir(TailDest_RSI, IR::OpSizeToSize(Size)));
  } else {
    // Calculate flags early. because end of block
    CalculateDeferredFlags();

    ForeachDirection([this, Op, Size](int32_t PtrDir) {
      // XXX: Theoretically LODS could be optimized to
      // RSI += {-}(RCX * Size)
      // RAX = [RSI - Size]
      // But this might violate the case of an application scanning pages for read permission and catching the fault
      // May or may not matter

      auto JumpStart = Jump();
      // Make sure to start a new block after ending this one
      auto LoopStart = CreateNewCodeBlockAfter(GetCurrentBlock());
      SetJumpTarget(JumpStart, LoopStart);
      SetCurrentCodeBlock(LoopStart);
      StartNewBlock();

      Ref Counter = LoadGPRRegister(X86State::REG_RCX);

      // Can we end the block?

      // We leave if RCX = 0
      auto CondJump_ = CondJump(Counter, {COND_EQ});

      auto LoopTail = CreateNewCodeBlockAfter(LoopStart);
      SetFalseJumpTarget(CondJump_, LoopTail);
      SetCurrentCodeBlock(LoopTail);
      StartNewBlock();

      // Working loop
      {
        Ref Dest_RSI = MakeSegmentAddress(X86State::REG_RSI, Op->Flags, X86Tables::DecodeFlags::FLAG_DS_PREFIX);

        auto Src = _LoadMemAutoTSO(GPRClass, Size, Dest_RSI, Size);

        StoreResult(GPRClass, Op, Src, OpSize::iInvalid);