365 lines
9.5 KiB
C++
365 lines
9.5 KiB
C++
#include "rar.hpp"
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RarVM::RarVM()
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{
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Mem=NULL;
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}
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RarVM::~RarVM()
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{
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delete[] Mem;
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}
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void RarVM::Init()
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{
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if (Mem==NULL)
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Mem=new byte[VM_MEMSIZE+4];
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}
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void RarVM::Execute(VM_PreparedProgram *Prg)
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{
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memcpy(R,Prg->InitR,sizeof(Prg->InitR));
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Prg->FilteredData=NULL;
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if (Prg->Type!=VMSF_NONE)
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{
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bool Success=ExecuteStandardFilter(Prg->Type);
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uint BlockSize=Prg->InitR[4] & VM_MEMMASK;
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Prg->FilteredDataSize=BlockSize;
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if (Prg->Type==VMSF_DELTA || Prg->Type==VMSF_RGB || Prg->Type==VMSF_AUDIO)
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Prg->FilteredData=2*BlockSize>VM_MEMSIZE || !Success ? Mem:Mem+BlockSize;
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else
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Prg->FilteredData=Mem;
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}
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}
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void RarVM::Prepare(byte *Code,uint CodeSize,VM_PreparedProgram *Prg)
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{
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// Calculate the single byte XOR checksum to check validity of VM code.
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byte XorSum=0;
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for (uint I=1;I<CodeSize;I++)
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XorSum^=Code[I];
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if (XorSum!=Code[0])
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return;
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struct StandardFilters
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{
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uint Length;
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uint CRC;
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VM_StandardFilters Type;
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} static StdList[]={
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53, 0xad576887, VMSF_E8,
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57, 0x3cd7e57e, VMSF_E8E9,
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120, 0x3769893f, VMSF_ITANIUM,
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29, 0x0e06077d, VMSF_DELTA,
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149, 0x1c2c5dc8, VMSF_RGB,
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216, 0xbc85e701, VMSF_AUDIO
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};
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uint CodeCRC=CRC32(0xffffffff,Code,CodeSize)^0xffffffff;
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for (uint I=0;I<ASIZE(StdList);I++)
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if (StdList[I].CRC==CodeCRC && StdList[I].Length==CodeSize)
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{
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Prg->Type=StdList[I].Type;
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break;
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}
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}
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uint RarVM::ReadData(BitInput &Inp)
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{
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uint Data=Inp.fgetbits();
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switch(Data&0xc000)
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{
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case 0:
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Inp.faddbits(6);
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return (Data>>10)&0xf;
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case 0x4000:
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if ((Data&0x3c00)==0)
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{
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Data=0xffffff00|((Data>>2)&0xff);
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Inp.faddbits(14);
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}
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else
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{
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Data=(Data>>6)&0xff;
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Inp.faddbits(10);
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}
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return Data;
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case 0x8000:
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Inp.faddbits(2);
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Data=Inp.fgetbits();
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Inp.faddbits(16);
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return Data;
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default:
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Inp.faddbits(2);
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Data=(Inp.fgetbits()<<16);
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Inp.faddbits(16);
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Data|=Inp.fgetbits();
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Inp.faddbits(16);
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return Data;
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}
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}
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void RarVM::SetMemory(size_t Pos,byte *Data,size_t DataSize)
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{
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if (Pos<VM_MEMSIZE && Data!=Mem+Pos)
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{
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// We can have NULL Data for invalid filters with DataSize==0. While most
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// sensible memmove implementations do not care about data if size is 0,
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// let's follow the standard and check the size first.
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size_t CopySize=Min(DataSize,VM_MEMSIZE-Pos);
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if (CopySize!=0)
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memmove(Mem+Pos,Data,CopySize);
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}
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}
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bool RarVM::ExecuteStandardFilter(VM_StandardFilters FilterType)
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{
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switch(FilterType)
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{
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case VMSF_E8:
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case VMSF_E8E9:
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{
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byte *Data=Mem;
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uint DataSize=R[4],FileOffset=R[6];
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if (DataSize>VM_MEMSIZE || DataSize<4)
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return false;
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const uint FileSize=0x1000000;
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byte CmpByte2=FilterType==VMSF_E8E9 ? 0xe9:0xe8;
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for (uint CurPos=0;CurPos<DataSize-4;)
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{
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byte CurByte=*(Data++);
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CurPos++;
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if (CurByte==0xe8 || CurByte==CmpByte2)
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{
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uint Offset=CurPos+FileOffset;
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uint Addr=RawGet4(Data);
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// We check 0x80000000 bit instead of '< 0' comparison
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// not assuming int32 presence or uint size and endianness.
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if ((Addr & 0x80000000)!=0) // Addr<0
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{
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if (((Addr+Offset) & 0x80000000)==0) // Addr+Offset>=0
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RawPut4(Addr+FileSize,Data);
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}
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else
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if (((Addr-FileSize) & 0x80000000)!=0) // Addr<FileSize
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RawPut4(Addr-Offset,Data);
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Data+=4;
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CurPos+=4;
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}
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}
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}
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break;
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case VMSF_ITANIUM:
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{
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byte *Data=Mem;
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uint DataSize=R[4],FileOffset=R[6];
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if (DataSize>VM_MEMSIZE || DataSize<21)
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return false;
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uint CurPos=0;
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FileOffset>>=4;
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while (CurPos<DataSize-21)
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{
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int Byte=(Data[0]&0x1f)-0x10;
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if (Byte>=0)
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{
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static byte Masks[16]={4,4,6,6,0,0,7,7,4,4,0,0,4,4,0,0};
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byte CmdMask=Masks[Byte];
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if (CmdMask!=0)
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for (uint I=0;I<=2;I++)
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if (CmdMask & (1<<I))
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{
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uint StartPos=I*41+5;
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uint OpType=FilterItanium_GetBits(Data,StartPos+37,4);
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if (OpType==5)
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{
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uint Offset=FilterItanium_GetBits(Data,StartPos+13,20);
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FilterItanium_SetBits(Data,(Offset-FileOffset)&0xfffff,StartPos+13,20);
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}
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}
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}
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Data+=16;
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CurPos+=16;
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FileOffset++;
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}
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}
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break;
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case VMSF_DELTA:
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{
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uint DataSize=R[4],Channels=R[0],SrcPos=0,Border=DataSize*2;
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if (DataSize>VM_MEMSIZE/2 || Channels>MAX3_UNPACK_CHANNELS || Channels==0)
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return false;
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// Bytes from same channels are grouped to continual data blocks,
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// so we need to place them back to their interleaving positions.
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for (uint CurChannel=0;CurChannel<Channels;CurChannel++)
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{
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byte PrevByte=0;
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for (uint DestPos=DataSize+CurChannel;DestPos<Border;DestPos+=Channels)
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Mem[DestPos]=(PrevByte-=Mem[SrcPos++]);
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}
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}
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break;
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case VMSF_RGB:
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{
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uint DataSize=R[4],Width=R[0]-3,PosR=R[1];
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if (DataSize>VM_MEMSIZE/2 || DataSize<3 || Width>DataSize || PosR>2)
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return false;
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byte *SrcData=Mem,*DestData=SrcData+DataSize;
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const uint Channels=3;
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for (uint CurChannel=0;CurChannel<Channels;CurChannel++)
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{
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uint PrevByte=0;
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for (uint I=CurChannel;I<DataSize;I+=Channels)
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{
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uint Predicted;
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if (I>=Width+3)
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{
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byte *UpperData=DestData+I-Width;
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uint UpperByte=*UpperData;
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uint UpperLeftByte=*(UpperData-3);
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Predicted=PrevByte+UpperByte-UpperLeftByte;
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int pa=abs((int)(Predicted-PrevByte));
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int pb=abs((int)(Predicted-UpperByte));
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int pc=abs((int)(Predicted-UpperLeftByte));
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if (pa<=pb && pa<=pc)
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Predicted=PrevByte;
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else
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if (pb<=pc)
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Predicted=UpperByte;
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else
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Predicted=UpperLeftByte;
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}
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else
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Predicted=PrevByte;
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DestData[I]=PrevByte=(byte)(Predicted-*(SrcData++));
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}
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}
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for (uint I=PosR,Border=DataSize-2;I<Border;I+=3)
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{
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byte G=DestData[I+1];
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DestData[I]+=G;
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DestData[I+2]+=G;
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}
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}
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break;
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case VMSF_AUDIO:
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{
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uint DataSize=R[4],Channels=R[0];
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byte *SrcData=Mem,*DestData=SrcData+DataSize;
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// In fact, audio channels never exceed 4.
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if (DataSize>VM_MEMSIZE/2 || Channels>128 || Channels==0)
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return false;
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for (uint CurChannel=0;CurChannel<Channels;CurChannel++)
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{
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uint PrevByte=0,PrevDelta=0,Dif[7];
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int D1=0,D2=0,D3;
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int K1=0,K2=0,K3=0;
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memset(Dif,0,sizeof(Dif));
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for (uint I=CurChannel,ByteCount=0;I<DataSize;I+=Channels,ByteCount++)
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{
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D3=D2;
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D2=PrevDelta-D1;
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D1=PrevDelta;
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uint Predicted=8*PrevByte+K1*D1+K2*D2+K3*D3;
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Predicted=(Predicted>>3) & 0xff;
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uint CurByte=*(SrcData++);
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Predicted-=CurByte;
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DestData[I]=Predicted;
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PrevDelta=(signed char)(Predicted-PrevByte);
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PrevByte=Predicted;
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int D=(signed char)CurByte;
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// Left shift of negative value is undefined behavior in C++,
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// so we cast it to unsigned to follow the standard.
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D=(uint)D<<3;
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Dif[0]+=abs(D);
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Dif[1]+=abs(D-D1);
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Dif[2]+=abs(D+D1);
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Dif[3]+=abs(D-D2);
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Dif[4]+=abs(D+D2);
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Dif[5]+=abs(D-D3);
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Dif[6]+=abs(D+D3);
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if ((ByteCount & 0x1f)==0)
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{
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uint MinDif=Dif[0],NumMinDif=0;
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Dif[0]=0;
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for (uint J=1;J<ASIZE(Dif);J++)
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{
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if (Dif[J]<MinDif)
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{
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MinDif=Dif[J];
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NumMinDif=J;
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}
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Dif[J]=0;
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}
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switch(NumMinDif)
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{
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case 1: if (K1>=-16) K1--; break;
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case 2: if (K1 < 16) K1++; break;
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case 3: if (K2>=-16) K2--; break;
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case 4: if (K2 < 16) K2++; break;
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case 5: if (K3>=-16) K3--; break;
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case 6: if (K3 < 16) K3++; break;
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}
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}
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}
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}
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}
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break;
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}
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return true;
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}
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uint RarVM::FilterItanium_GetBits(byte *Data,uint BitPos,uint BitCount)
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{
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uint InAddr=BitPos/8;
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uint InBit=BitPos&7;
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uint BitField=(uint)Data[InAddr++];
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BitField|=(uint)Data[InAddr++] << 8;
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BitField|=(uint)Data[InAddr++] << 16;
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BitField|=(uint)Data[InAddr] << 24;
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BitField >>= InBit;
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return BitField & (0xffffffff>>(32-BitCount));
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}
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void RarVM::FilterItanium_SetBits(byte *Data,uint BitField,uint BitPos,uint BitCount)
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{
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uint InAddr=BitPos/8;
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uint InBit=BitPos&7;
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uint AndMask=0xffffffff>>(32-BitCount);
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AndMask=~(AndMask<<InBit);
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BitField<<=InBit;
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for (uint I=0;I<4;I++)
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{
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Data[InAddr+I]&=AndMask;
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Data[InAddr+I]|=BitField;
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AndMask=(AndMask>>8)|0xff000000;
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BitField>>=8;
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}
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}
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