#include "rar.hpp"
RarVM::RarVM()
{
Mem=NULL;
}
RarVM::~RarVM()
{
delete[] Mem;
}
void RarVM::Init()
{
if (Mem==NULL)
Mem=new byte[VM_MEMSIZE+4];
}
void RarVM::Execute(VM_PreparedProgram *Prg)
{
memcpy(R,Prg->InitR,sizeof(Prg->InitR));
Prg->FilteredData=NULL;
if (Prg->Type!=VMSF_NONE)
{
bool Success=ExecuteStandardFilter(Prg->Type);
uint BlockSize=Prg->InitR[4] & VM_MEMMASK;
Prg->FilteredDataSize=BlockSize;
if (Prg->Type==VMSF_DELTA || Prg->Type==VMSF_RGB || Prg->Type==VMSF_AUDIO)
Prg->FilteredData=2*BlockSize>VM_MEMSIZE || !Success ? Mem:Mem+BlockSize;
else
Prg->FilteredData=Mem;
}
}
void RarVM::Prepare(byte *Code,uint CodeSize,VM_PreparedProgram *Prg)
{
// Calculate the single byte XOR checksum to check validity of VM code.
byte XorSum=0;
for (uint I=1;I<CodeSize;I++)
XorSum^=Code[I];
if (XorSum!=Code[0])
return;
struct StandardFilters
{
uint Length;
uint CRC;
VM_StandardFilters Type;
} static StdList[]={
53, 0xad576887, VMSF_E8,
57, 0x3cd7e57e, VMSF_E8E9,
120, 0x3769893f, VMSF_ITANIUM,
29, 0x0e06077d, VMSF_DELTA,
149, 0x1c2c5dc8, VMSF_RGB,
216, 0xbc85e701, VMSF_AUDIO
};
uint CodeCRC=CRC32(0xffffffff,Code,CodeSize)^0xffffffff;
for (uint I=0;I<ASIZE(StdList);I++)
if (StdList[I].CRC==CodeCRC && StdList[I].Length==CodeSize)
{
Prg->Type=StdList[I].Type;
break;
}
}
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;
}
}
void RarVM::SetMemory(size_t Pos,byte *Data,size_t DataSize)
{
if (Pos<VM_MEMSIZE && Data!=Mem+Pos)
{
// We can have NULL Data for invalid filters with DataSize==0. While most
// sensible memmove implementations do not care about data if size is 0,
// let's follow the standard and check the size first.
size_t CopySize=Min(DataSize,VM_MEMSIZE-Pos);
if (CopySize!=0)
memmove(Mem+Pos,Data,CopySize);
}
}
bool RarVM::ExecuteStandardFilter(VM_StandardFilters FilterType)
{
switch(FilterType)
{
case VMSF_E8:
case VMSF_E8E9:
{
byte *Data=Mem;
uint DataSize=R[4],FileOffset=R[6];
if (DataSize>VM_MEMSIZE || DataSize<4)
return false;
const uint FileSize=0x1000000;
byte CmpByte2=FilterType==VMSF_E8E9 ? 0xe9:0xe8;
for (uint CurPos=0;CurPos<DataSize-4;)
{
byte CurByte=*(Data++);
CurPos++;
if (CurByte==0xe8 || CurByte==CmpByte2)
{
uint Offset=CurPos+FileOffset;
uint Addr=RawGet4(Data);
// We check 0x80000000 bit instead of '< 0' comparison
// not assuming int32 presence or uint size and endianness.
if ((Addr & 0x80000000)!=0) // Addr<0
{
if (((Addr+Offset) & 0x80000000)==0) // Addr+Offset>=0
RawPut4(Addr+FileSize,Data);
}
else
if (((Addr-FileSize) & 0x80000000)!=0) // Addr<FileSize
RawPut4(Addr-Offset,Data);
Data+=4;
CurPos+=4;
}
}
}
break;
case VMSF_ITANIUM:
{
byte *Data=Mem;
uint DataSize=R[4],FileOffset=R[6];
if (DataSize>VM_MEMSIZE || DataSize<21)
return false;
uint CurPos=0;
FileOffset>>=4;
while (CurPos<DataSize-21)
{
int Byte=(Data[0]&0x1f)-0x10;
if (Byte>=0)
{
static byte Masks[16]={4,4,6,6,0,0,7,7,4,4,0,0,4,4,0,0};
byte CmdMask=Masks[Byte];
if (CmdMask!=0)
for (uint I=0;I<=2;I++)
if (CmdMask & (1<<I))
{
uint StartPos=I*41+5;
uint OpType=FilterItanium_GetBits(Data,StartPos+37,4);
if (OpType==5)
{
uint Offset=FilterItanium_GetBits(Data,StartPos+13,20);
FilterItanium_SetBits(Data,(Offset-FileOffset)&0xfffff,StartPos+13,20);
}
}
}
Data+=16;
CurPos+=16;
FileOffset++;
}
}
break;
case VMSF_DELTA:
{
uint DataSize=R[4],Channels=R[0],SrcPos=0,Border=DataSize*2;
if (DataSize>VM_MEMSIZE/2 || Channels>MAX3_UNPACK_CHANNELS || Channels==0)
return false;
// Bytes from same channels are grouped to continual data blocks,
// so we need to place them back to their interleaving positions.
for (uint CurChannel=0;CurChannel<Channels;CurChannel++)
{
byte PrevByte=0;
for (uint DestPos=DataSize+CurChannel;DestPos<Border;DestPos+=Channels)
Mem[DestPos]=(PrevByte-=Mem[SrcPos++]);
}
}
break;
case VMSF_RGB:
{
uint DataSize=R[4],Width=R[0]-3,PosR=R[1];
if (DataSize>VM_MEMSIZE/2 || DataSize<3 || Width>DataSize || PosR>2)
return false;
byte *SrcData=Mem,*DestData=SrcData+DataSize;
const uint Channels=3;
for (uint CurChannel=0;CurChannel<Channels;CurChannel++)
{
uint PrevByte=0;
for (uint I=CurChannel;I<DataSize;I+=Channels)
{
uint Predicted;
if (I>=Width+3)
{
byte *UpperData=DestData+I-Width;
uint UpperByte=*UpperData;
uint UpperLeftByte=*(UpperData-3);
Predicted=PrevByte+UpperByte-UpperLeftByte;
int pa=abs((int)(Predicted-PrevByte));
int pb=abs((int)(Predicted-UpperByte));
int pc=abs((int)(Predicted-UpperLeftByte));
if (pa<=pb && pa<=pc)
Predicted=PrevByte;
else
if (pb<=pc)
Predicted=UpperByte;
else
Predicted=UpperLeftByte;
}
else
Predicted=PrevByte;
DestData[I]=PrevByte=(byte)(Predicted-*(SrcData++));
}
}
for (uint I=PosR,Border=DataSize-2;I<Border;I+=3)
{
byte G=DestData[I+1];
DestData[I]+=G;
DestData[I+2]+=G;
}
}
break;
case VMSF_AUDIO:
{
uint DataSize=R[4],Channels=R[0];
byte *SrcData=Mem,*DestData=SrcData+DataSize;
// In fact, audio channels never exceed 4.
if (DataSize>VM_MEMSIZE/2 || Channels>128 || Channels==0)
return false;
for (uint CurChannel=0;CurChannel<Channels;CurChannel++)
{
uint PrevByte=0,PrevDelta=0,Dif[7];
int D1=0,D2=0,D3;
int K1=0,K2=0,K3=0;
memset(Dif,0,sizeof(Dif));
for (uint I=CurChannel,ByteCount=0;I<DataSize;I+=Channels,ByteCount++)
{
D3=D2;
D2=PrevDelta-D1;
D1=PrevDelta;
uint Predicted=8*PrevByte+K1*D1+K2*D2+K3*D3;
Predicted=(Predicted>>3) & 0xff;
uint CurByte=*(SrcData++);
Predicted-=CurByte;
DestData[I]=Predicted;
PrevDelta=(signed char)(Predicted-PrevByte);
PrevByte=Predicted;
int D=(signed char)CurByte;
// Left shift of negative value is undefined behavior in C++,
// so we cast it to unsigned to follow the standard.
D=(uint)D<<3;
Dif[0]+=abs(D);
Dif[1]+=abs(D-D1);
Dif[2]+=abs(D+D1);
Dif[3]+=abs(D-D2);
Dif[4]+=abs(D+D2);
Dif[5]+=abs(D-D3);
Dif[6]+=abs(D+D3);
if ((ByteCount & 0x1f)==0)
{
uint MinDif=Dif[0],NumMinDif=0;
Dif[0]=0;
for (uint J=1;J<ASIZE(Dif);J++)
{
if (Dif[J]<MinDif)
{
MinDif=Dif[J];
NumMinDif=J;
}
Dif[J]=0;
}
switch(NumMinDif)
{
case 1: if (K1>=-16) K1--; break;
case 2: if (K1 < 16) K1++; break;
case 3: if (K2>=-16) K2--; break;
case 4: if (K2 < 16) K2++; break;
case 5: if (K3>=-16) K3--; break;
case 6: if (K3 < 16) K3++; break;
}
}
}
}
}
break;
}
return true;
}
uint RarVM::FilterItanium_GetBits(byte *Data,uint BitPos,uint BitCount)
{
uint InAddr=BitPos/8;
uint InBit=BitPos&7;
uint BitField=(uint)Data[InAddr++];
BitField|=(uint)Data[InAddr++] << 8;
BitField|=(uint)Data[InAddr++] << 16;
BitField|=(uint)Data[InAddr] << 24;
BitField >>= InBit;
return BitField & (0xffffffff>>(32-BitCount));
}
void RarVM::FilterItanium_SetBits(byte *Data,uint BitField,uint BitPos,uint BitCount)
{
uint InAddr=BitPos/8;
uint InBit=BitPos&7;
uint AndMask=0xffffffff>>(32-BitCount);
AndMask=~(AndMask<<InBit);
BitField<<=InBit;
for (uint I=0;I<4;I++)
{
Data[InAddr+I]&=AndMask;
Data[InAddr+I]|=BitField;
AndMask=(AndMask>>8)|0xff000000;
BitField>>=8;
}
}