rarvm.cpp

我把unrar的代码整理成vc工程了

      case VM_PUSH:
        R[7]-=4;
        SET_VALUE(false,(uint *)&Mem[R[7]&VM_MEMMASK],GET_VALUE(false,Op1));
        break;
      case VM_POP:
        SET_VALUE(false,Op1,GET_VALUE(false,(uint *)&Mem[R[7] & VM_MEMMASK]));
        R[7]+=4;
        break;
      case VM_CALL:
        R[7]-=4;
        SET_VALUE(false,(uint *)&Mem[R[7]&VM_MEMMASK],Cmd-PreparedCode+1);
        SET_IP(GET_VALUE(false,Op1));
        continue;
      case VM_NOT:
        SET_VALUE(Cmd->ByteMode,Op1,~GET_VALUE(Cmd->ByteMode,Op1));
        break;
      case VM_SHL:
        {
          uint Value1=GET_VALUE(Cmd->ByteMode,Op1);
          uint Value2=GET_VALUE(Cmd->ByteMode,Op2);
          uint Result=UINT32(Value1<<Value2);
          Flags=(Result==0 ? VM_FZ:(Result&VM_FS))|((Value1<<(Value2-1))&0x80000000 ? VM_FC:0);
          SET_VALUE(Cmd->ByteMode,Op1,Result);
        }
        break;
      case VM_SHR:
        {
          uint Value1=GET_VALUE(Cmd->ByteMode,Op1);
          uint Value2=GET_VALUE(Cmd->ByteMode,Op2);
          uint Result=UINT32(Value1>>Value2);
          Flags=(Result==0 ? VM_FZ:(Result&VM_FS))|((Value1>>(Value2-1))&VM_FC);
          SET_VALUE(Cmd->ByteMode,Op1,Result);
        }
        break;
      case VM_SAR:
        {
          uint Value1=GET_VALUE(Cmd->ByteMode,Op1);
          uint Value2=GET_VALUE(Cmd->ByteMode,Op2);
          uint Result=UINT32(((int)Value1)>>Value2);
          Flags=(Result==0 ? VM_FZ:(Result&VM_FS))|((Value1>>(Value2-1))&VM_FC);
          SET_VALUE(Cmd->ByteMode,Op1,Result);
        }
        break;
      case VM_NEG:
        {
          uint Result=UINT32(-GET_VALUE(Cmd->ByteMode,Op1));
          Flags=Result==0 ? VM_FZ:VM_FC|(Result&VM_FS);
          SET_VALUE(Cmd->ByteMode,Op1,Result);
        }
        break;
#ifdef VM_OPTIMIZE
      case VM_NEGB:
        SET_VALUE(true,Op1,-GET_VALUE(true,Op1));
        break;
      case VM_NEGD:
        SET_VALUE(false,Op1,-GET_VALUE(false,Op1));
        break;
#endif
      case VM_PUSHA:
        {
          const int RegCount=sizeof(R)/sizeof(R[0]);
          for (int I=0,SP=R[7]-4;I<RegCount;I++,SP-=4)
            SET_VALUE(false,(uint *)&Mem[SP & VM_MEMMASK],R[I]);
          R[7]-=RegCount*4;
        }
        break;
      case VM_POPA:
        {
          const int RegCount=sizeof(R)/sizeof(R[0]);
          for (uint I=0,SP=R[7];I<RegCount;I++,SP+=4)
            R[7-I]=GET_VALUE(false,(uint *)&Mem[SP & VM_MEMMASK]);
        }
        break;
      case VM_PUSHF:
        R[7]-=4;
        SET_VALUE(false,(uint *)&Mem[R[7]&VM_MEMMASK],Flags);
        break;
      case VM_POPF:
        Flags=GET_VALUE(false,(uint *)&Mem[R[7] & VM_MEMMASK]);
        R[7]+=4;
        break;
      case VM_MOVZX:
        SET_VALUE(false,Op1,GET_VALUE(true,Op2));
        break;
      case VM_MOVSX:
        SET_VALUE(false,Op1,(signed char)GET_VALUE(true,Op2));
        break;
      case VM_XCHG:
        {
          uint Value1=GET_VALUE(Cmd->ByteMode,Op1);
          SET_VALUE(Cmd->ByteMode,Op1,GET_VALUE(Cmd->ByteMode,Op2));
          SET_VALUE(Cmd->ByteMode,Op2,Value1);
        }
        break;
      case VM_MUL:
        {
          uint Result=GET_VALUE(Cmd->ByteMode,Op1)*GET_VALUE(Cmd->ByteMode,Op2);
          SET_VALUE(Cmd->ByteMode,Op1,Result);
        }
        break;
      case VM_DIV:
        {
          uint Divider=GET_VALUE(Cmd->ByteMode,Op2);
          if (Divider!=0)
          {
            uint Result=GET_VALUE(Cmd->ByteMode,Op1)/Divider;
            SET_VALUE(Cmd->ByteMode,Op1,Result);
          }
        }
        break;
      case VM_ADC:
        {
          uint Value1=GET_VALUE(Cmd->ByteMode,Op1);
          uint FC=(Flags&VM_FC);
          uint Result=UINT32(Value1+GET_VALUE(Cmd->ByteMode,Op2)+FC);
          if (Cmd->ByteMode)
            Result&=0xff;
          Flags=(Result<Value1 || Result==Value1 && FC)|(Result==0 ? VM_FZ:(Result&VM_FS));
          SET_VALUE(Cmd->ByteMode,Op1,Result);
        }
        break;
      case VM_SBB:
        {
          uint Value1=GET_VALUE(Cmd->ByteMode,Op1);
          uint FC=(Flags&VM_FC);
          uint Result=UINT32(Value1-GET_VALUE(Cmd->ByteMode,Op2)-FC);
          if (Cmd->ByteMode)
            Result&=0xff;
          Flags=(Result>Value1 || Result==Value1 && FC)|(Result==0 ? VM_FZ:(Result&VM_FS));
          SET_VALUE(Cmd->ByteMode,Op1,Result);
        }
        break;
#endif  // for #ifndef NORARVM
      case VM_RET:
        if (R[7]>=VM_MEMSIZE)
          return(true);
        SET_IP(GET_VALUE(false,(uint *)&Mem[R[7] & VM_MEMMASK]));
        R[7]+=4;
        continue;
#ifdef VM_STANDARDFILTERS
      case VM_STANDARD:
        ExecuteStandardFilter((VM_StandardFilters)Cmd->Op1.Data);
        break;
#endif
      case VM_PRINT:
        break;
    }
    Cmd++;
    --MaxOpCount;
  }
}




void RarVM::Prepare(byte *Code,int CodeSize,VM_PreparedProgram *Prg)
{
  InitBitInput();
  memcpy(InBuf,Code,Min(CodeSize,BitInput::MAX_SIZE));

  // Calculate the single byte XOR checksum to check validity of VM code.
  byte XorSum=0;
  for (int I=1;I<CodeSize;I++)
    XorSum^=Code[I];

  faddbits(8);

  Prg->CmdCount=0;
  if (XorSum==Code[0]) // VM code is valid if equal.
  {
#ifdef VM_STANDARDFILTERS
    VM_StandardFilters FilterType=IsStandardFilter(Code,CodeSize);
    if (FilterType!=VMSF_NONE)
    {
      // VM code is found among standard filters.
      Prg->Cmd.Add(1);
      VM_PreparedCommand *CurCmd=&Prg->Cmd[Prg->CmdCount++];
      CurCmd->OpCode=VM_STANDARD;
      CurCmd->Op1.Data=FilterType;
      CurCmd->Op1.Addr=&CurCmd->Op1.Data;
      CurCmd->Op2.Addr=&CurCmd->Op2.Data;
      CurCmd->Op1.Type=CurCmd->Op2.Type=VM_OPNONE;
      CodeSize=0;
    }
#endif  
    uint DataFlag=fgetbits();
    faddbits(1);

    // Read static data contained in DB operators. This data cannot be
    // changed, it is a part of VM code, not a filter parameter.

    if (DataFlag&0x8000)
    {
      int DataSize=ReadData(*this)+1;
      for (int I=0;InAddr<CodeSize && I<DataSize;I++)
      {
        Prg->StaticData.Add(1);
        Prg->StaticData[I]=fgetbits()>>8;
        faddbits(8);
      }
    }

    while (InAddr<CodeSize)
    {
      Prg->Cmd.Add(1);
      VM_PreparedCommand *CurCmd=&Prg->Cmd[Prg->CmdCount];
      uint Data=fgetbits();
      if ((Data&0x8000)==0)
      {
        CurCmd->OpCode=(VM_Commands)(Data>>12);
        faddbits(4);
      }
      else
      {
        CurCmd->OpCode=(VM_Commands)((Data>>10)-24);
        faddbits(6);
      }
      if (VM_CmdFlags[CurCmd->OpCode] & VMCF_BYTEMODE)
      {
        CurCmd->ByteMode=fgetbits()>>15;
        faddbits(1);
      }
      else
        CurCmd->ByteMode=0;
      CurCmd->Op1.Type=CurCmd->Op2.Type=VM_OPNONE;
      int OpNum=(VM_CmdFlags[CurCmd->OpCode] & VMCF_OPMASK);
      CurCmd->Op1.Addr=CurCmd->Op2.Addr=NULL;
      if (OpNum>0)
      {
        DecodeArg(CurCmd->Op1,CurCmd->ByteMode); // reading the first operand
        if (OpNum==2)
          DecodeArg(CurCmd->Op2,CurCmd->ByteMode); // reading the second operand
        else
        {
          if (CurCmd->Op1.Type==VM_OPINT && (VM_CmdFlags[CurCmd->OpCode]&(VMCF_JUMP|VMCF_PROC)))
          {
            // Calculating jump distance.
            int Distance=CurCmd->Op1.Data;
            if (Distance>=256)
              Distance-=256;
            else
            {
              if (Distance>=136)
                Distance-=264;
              else
                if (Distance>=16)
                  Distance-=8;
                else
                  if (Distance>=8)
                    Distance-=16;
              Distance+=Prg->CmdCount;
            }
            CurCmd->Op1.Data=Distance;
          }
        }
      }
      Prg->CmdCount++;
    }
  }

  // Adding RET command at the end of program.
  Prg->Cmd.Add(1);
  VM_PreparedCommand *CurCmd=&Prg->Cmd[Prg->CmdCount++];
  CurCmd->OpCode=VM_RET;
  CurCmd->Op1.Addr=&CurCmd->Op1.Data;
  CurCmd->Op2.Addr=&CurCmd->Op2.Data;
  CurCmd->Op1.Type=CurCmd->Op2.Type=VM_OPNONE;

  // If operand 'Addr' field has not been set by DecodeArg calls above,
  // let's set it to point to operand 'Data' field. It is necessary for
  // VM_OPINT type operands (usual integers) or maybe if something was 
  // not set properly for other operands. 'Addr' field is required
  // for quicker addressing of operand data.
  for (int I=0;I<Prg->CmdCount;I++)
  {
    VM_PreparedCommand *Cmd=&Prg->Cmd[I];
    if (Cmd->Op1.Addr==NULL)
      Cmd->Op1.Addr=&Cmd->Op1.Data;
    if (Cmd->Op2.Addr==NULL)
      Cmd->Op2.Addr=&Cmd->Op2.Data;
  }

#ifdef VM_OPTIMIZE
  if (CodeSize!=0)
    Optimize(Prg);
#endif
}


void RarVM::DecodeArg(VM_PreparedOperand &Op,bool ByteMode)
{
  uint Data=fgetbits();
  if (Data & 0x8000)
  {
    Op.Type=VM_OPREG;     // Operand is register (R[0]..R[7])
    Op.Data=(Data>>12)&7; // Register number
    Op.Addr=&R[Op.Data];  // Register address
    faddbits(4);          // 1 flag bit and 3 register number bits 
  }
  else
    if ((Data & 0xc000)==0)
    {
      Op.Type=VM_OPINT;   // Operand is integer
      if (ByteMode)
      {
        Op.Data=(Data>>6) & 0xff;  // Byte integer.
        faddbits(10);
      }
      else
      {
        faddbits(2);
        Op.Data=ReadData(*this);   // 32 bit integer.
      }
    }
    else
    {
      // Operand is data addressed by register data, base address or both.
      Op.Type=VM_OPREGMEM;
      if ((Data & 0x2000)==0)
      {
        // Base address is zero, just use the address from register.
        Op.Data=(Data>>10)&7;
        Op.Addr=&R[Op.Data];
        Op.Base=0;
        faddbits(6);
      }
      else
      {
        if ((Data & 0x1000)==0)
        {
          // Use both register and base address.
          Op.Data=(Data>>9)&7;
          Op.Addr=&R[Op.Data];
          faddbits(7);
        }
        else
        {
          // Use base address only. Access memory by fixed address.
          Op.Data=0;
          faddbits(4);
        }
        Op.Base=ReadData(*this); // Read base address.
      }
    }
}


uint RarVM::ReadData(BitInput &Inp)
{
  uint Data=Inp.fgetbits();
  switch(Data&0xc000)
  {
    case 0:
      Inp.faddbits(6);
      return((Data>>10)&0xf);
    case 0x4000:
      if ((Data&0x3c00)==0)
      {
        Data=0xffffff00|((Data>>2)&0xff);
        Inp.faddbits(14);
      }
      else
      {
        Data=(Data>>6)&0xff;
        Inp.faddbits(10);
      }
      return(Data);
    case 0x8000:
      Inp.faddbits(2);
      Data=Inp.fgetbits();
      Inp.faddbits(16);
      return(Data);
    default:
      Inp.faddbits(2);
      Data=(Inp.fgetbits()<<16);
      Inp.faddbits(16);
      Data|=Inp.fgetbits();
      Inp.faddbits(16);
      return(Data);