urarlib.c

一个解RAR文件的开发库源码

	    }
      }

      WrPtr=UnpPtr;
    }

    if (UnpAudioBlock)
    {
      DecodeNumber((struct Decode *)MDPtr[CurChannel]);
      if (Number==256)
      {
        ReadTables();
        continue;
      }
      UnpBuf[UnpPtr++]=DecodeAudio(Number);
      if (++CurChannel==UnpChannels)
        CurChannel=0;
      DestUnpSize--;
      continue;
    }

    DecodeNumber((struct Decode *)&LD);
    if (Number<256)
    {
      UnpBuf[UnpPtr++]=(UBYTE)Number;
      DestUnpSize--;
      continue;
    }
    if (Number>269)
    {
      Length=LDecode[Number-=270]+3;
      if ((Bits=LBits[Number])>0)
      {
        GetBits();
        Length+=BitField>>(16-Bits);
        AddBits(Bits);
      }

      DecodeNumber((struct Decode *)&DD);
      Distance=DDecode[Number]+1;
      if ((Bits=DBits[Number])>0)
      {
        GetBits();
        Distance+=BitField>>(16-Bits);
        AddBits(Bits);
      }

      if (Distance>=0x40000L)
        Length++;

      if (Distance>=0x2000)
        Length++;

       LastDist=OldDist[OldDistPtr++ & 3]=Distance;
       DestUnpSize-=(LastLength=Length);
       while (Length--)
       {
         UnpBuf[UnpPtr]=UnpBuf[(UnpPtr-Distance) & MAXWINMASK];
         UnpPtr=(UnpPtr+1) & MAXWINMASK;
       }

      continue;
    }
    if (Number==269)
    {
      ReadTables();
      continue;
    }
    if (Number==256)
    {
      Length=LastLength;
      Distance=LastDist;
       LastDist=OldDist[OldDistPtr++ & 3]=Distance;
       DestUnpSize-=(LastLength=Length);
       while (Length--)
       {
         UnpBuf[UnpPtr]=UnpBuf[(UnpPtr-Distance) & MAXWINMASK];
         UnpPtr=(UnpPtr+1) & MAXWINMASK;
       }
      continue;
    }
    if (Number<261)
    {
      Distance=OldDist[(OldDistPtr-(Number-256)) & 3];
      DecodeNumber((struct Decode *)&RD);
      Length=LDecode[Number]+2;
      if ((Bits=LBits[Number])>0)
      {
        GetBits();
        Length+=BitField>>(16-Bits);
        AddBits(Bits);
      }
      if (Distance>=0x40000)
        Length++;
      if (Distance>=0x2000)
        Length++;
      if (Distance>=0x101)
        Length++;
       LastDist=OldDist[OldDistPtr++ & 3]=Distance;
       DestUnpSize-=(LastLength=Length);
       while (Length--)
       {
         UnpBuf[UnpPtr]=UnpBuf[(UnpPtr-Distance) & MAXWINMASK];
         UnpPtr=(UnpPtr+1) & MAXWINMASK;
       }
      continue;
    }
    if (Number<270)
    {
      Distance=SDDecode[Number-=261]+1;
      if ((Bits=SDBits[Number])>0)
      {
        GetBits();
        Distance+=BitField>>(16-Bits);
        AddBits(Bits);
      }
      Length=2;
       LastDist=OldDist[OldDistPtr++ & 3]=Distance;
       DestUnpSize-=(LastLength=Length);
       while (Length--)
       {
         UnpBuf[UnpPtr]=UnpBuf[(UnpPtr-Distance) & MAXWINMASK];
         UnpPtr=(UnpPtr+1) & MAXWINMASK;
       }
      continue;
   }
  }
  ReadLastTables();

  if (FileFound)                            /* flush buffer                 */
  {

    if (UnpPtr<WrPtr)
    {
	  if((*temp_output_buffer_offset + UnpPtr) > NewLhd.UnpSize)
	  {
	    debug_log("Fatal! Buffer overrun during decompression!");
		DestUnpSize=-1;						
	  } else
	  {
        /* copy extracted data to output buffer                             */
        memcpy(temp_output_buffer + *temp_output_buffer_offset, &UnpBuf[WrPtr], 
               (0-WrPtr) & MAXWINMASK);
        /* update offset within buffer                                      */
        *temp_output_buffer_offset+= (0-WrPtr) & MAXWINMASK;   
        /* copy extracted data to output buffer                             */
        memcpy(temp_output_buffer + *temp_output_buffer_offset, UnpBuf, UnpPtr);
        /* update offset within buffer                                      */
        *temp_output_buffer_offset+=UnpPtr;
	  }
    } else
    {
	  if((*temp_output_buffer_offset + (UnpPtr-WrPtr)) > NewLhd.UnpSize)
	  {
	 	debug_log("Fatal! Buffer overrun during decompression!");
		DestUnpSize=-1;						
	  } else
	  {
        /* copy extracted data to output buffer                             */
        memcpy(temp_output_buffer + *temp_output_buffer_offset, &UnpBuf[WrPtr],
               UnpPtr-WrPtr);   
        /* update offset within buffer                                      */
        *temp_output_buffer_offset+=UnpPtr-WrPtr;
	  }
    }
  }

  WrPtr=UnpPtr;
}


unsigned int UnpRead(unsigned char *Addr,unsigned int Count)
{
  int RetCode=0;
  unsigned int I,ReadSize,TotalRead=0;
  unsigned char *ReadAddr;
  ReadAddr=Addr;
  while (Count > 0)
  {
    ReadSize=(unsigned int)((Count>(unsigned long)UnpPackedSize) ? 
                                                  UnpPackedSize : Count);
#ifdef _USE_MEMORY_TO_MEMORY_DECOMPRESSION
    if(MemRARFile->data == NULL)
      return(0);
    RetCode=tread(MemRARFile, ReadAddr, ReadSize);
#else
    if (ArcPtr==NULL)
      return(0);
    RetCode=tread(ArcPtr,ReadAddr,ReadSize);
#endif
    CurUnpRead+=RetCode;
    ReadAddr+=RetCode;
    TotalRead+=RetCode;
    Count-=RetCode;
    UnpPackedSize-=RetCode;
      break;
  }
  if (RetCode!= -1)
  {
    RetCode=TotalRead;
    if (Encryption)
    {
      if (Encryption<20)
          {
            debug_log("Old Crypt() not supported!");
          }
      else
      {
        for (I=0;I<(unsigned int)RetCode;I+=16)
          DecryptBlock(&Addr[I]);
      }
    }
  }
  return(RetCode);
}


void UnpReadBuf(int FirstBuf)
{
  int RetCode;
  if (FirstBuf)
  {
    ReadTop=UnpRead(InBuf,sizeof(InBuf));
    InAddr=0;
  }
  else
  {
    memcpy(InBuf,&InBuf[sizeof(InBuf)-32],32);
    InAddr&=0x1f;
    RetCode=UnpRead(&InBuf[32],sizeof(InBuf)-32);
    if (RetCode>0)
      ReadTop=RetCode+32;
    else
      ReadTop=InAddr;
  }
}


void ReadTables(void)
{
  UBYTE BitLength[BC];
  unsigned char Table[MC*4];
  int TableSize,N,I;
  if (InAddr>sizeof(InBuf)-25)
    UnpReadBuf(0);
  GetBits();
  UnpAudioBlock=(BitField & 0x8000);

  if (!(BitField & 0x4000))
    memset(UnpOldTable,0,sizeof(UnpOldTable));
  AddBits(2);


  if (UnpAudioBlock)
  {
    UnpChannels=((BitField>>12) & 3)+1;
    if (CurChannel>=UnpChannels)
      CurChannel=0;
    AddBits(2);
    TableSize=MC*UnpChannels;
  }
  else
    TableSize=NC+DC+RC;


  for (I=0;I<BC;I++)
  {
    GetBits();
    BitLength[I]=(UBYTE)(BitField >> 12);
    AddBits(4);
  }
  MakeDecodeTables(BitLength,(struct Decode *)&BD,BC);
  I=0;
  while (I<TableSize)
  {
    if (InAddr>sizeof(InBuf)-5)
      UnpReadBuf(0);
    DecodeNumber((struct Decode *)&BD);
    if (Number<16)
      Table[I++]=(Number+UnpOldTable[I]) & 0xf;
    else
      if (Number==16)
      {
        GetBits();
        N=(BitField >> 14)+3;
        AddBits(2);
        while (N-- > 0 && I<TableSize)
        {
          Table[I]=Table[I-1];
          I++;
        }
      }
      else
      {
        if (Number==17)
        {
          GetBits();
          N=(BitField >> 13)+3;
          AddBits(3);
        }
        else
        {
          GetBits();
          N=(BitField >> 9)+11;
          AddBits(7);
        }
        while (N-- > 0 && I<TableSize)
          Table[I++]=0;
      }
  }
  if (UnpAudioBlock)
    for (I=0;I<UnpChannels;I++)
      MakeDecodeTables(&Table[I*MC],(struct Decode *)MDPtr[I],MC);
  else
  {
    MakeDecodeTables(&Table[0],(struct Decode *)&LD,NC);
    MakeDecodeTables(&Table[NC],(struct Decode *)&DD,DC);
    MakeDecodeTables(&Table[NC+DC],(struct Decode *)&RD,RC);
  }
  memcpy(UnpOldTable,Table,sizeof(UnpOldTable));
}


static void ReadLastTables(void)
{
  if (ReadTop>=InAddr+5)
  {
    if (UnpAudioBlock)
    {
      DecodeNumber((struct Decode *)MDPtr[CurChannel]);
      if (Number==256)
        ReadTables();
    }
    else
    {
      DecodeNumber((struct Decode *)&LD);
      if (Number==269)
        ReadTables();
    }
  }
}


static void MakeDecodeTables(unsigned char *LenTab,
                             struct Decode *Dec,
                             int Size)
{
  int LenCount[16],TmpPos[16],I;
  long M,N;
  memset(LenCount,0,sizeof(LenCount));
  for (I=0;I<Size;I++)
    LenCount[LenTab[I] & 0xF]++;

  LenCount[0]=0;
  for (TmpPos[0]=Dec->DecodePos[0]=Dec->DecodeLen[0]=0,N=0,I=1;I<16;I++)
  {
    N=2*(N+LenCount[I]);
    M=N<<(15-I);
    if (M>0xFFFF)
      M=0xFFFF;
    Dec->DecodeLen[I]=(unsigned int)M;
    TmpPos[I]=Dec->DecodePos[I]=Dec->DecodePos[I-1]+LenCount[I-1];
  }

  for (I=0;I<Size;I++)
    if (LenTab[I]!=0)
      Dec->DecodeNum[TmpPos[LenTab[I] & 0xF]++]=I;
  Dec->MaxNum=Size;
}


static void DecodeNumber(struct Decode *Deco)
/* *** 52.6% of all CPU time is spent within this function!!!               */
{
  unsigned int I;
  register unsigned int N;
  GetBits();

#ifdef _USE_ASM
  
#ifdef _WIN_32
 __asm {

    xor eax, eax
    mov eax, BitField                       // N=BitField & 0xFFFE;
    and eax, 0xFFFFFFFE
    mov [N], eax                                                 
    mov edx, [Deco]                         // EAX=N, EDX=Deco

          cmp  eax, dword ptr[edx + 8*4 + 4]// if (N<Dec->DecodeLen[8])
          jae  else_G

             cmp  eax, dword ptr[edx + 4*4 + 4]// if (N<Dec->DecodeLen[4]) 
             jae  else_F


                cmp  eax, dword ptr[edx + 2*4 + 4]// if (N<Dec->DecodeLen[2]) 
                jae  else_C

                   cmp  eax, dword ptr[edx + 1*4 + 4]// if (N<Dec->DecodeLen[1]) 
                   jae  else_1
                   mov  I, 1                         //  I=1;
                   jmp  next_1
                 else_1:                             // else
                   mov  I, 2                         //  I=2;
                 next_1:
                
                jmp  next_C
              else_C:                             // else
                   
                   cmp  eax, dword ptr[edx + 3*4 + 4]// if (N<Dec->DecodeLen[3]) 
                   jae  else_2
                   mov  I, 3                         //  I=3;
                   jmp  next_2
                 else_2:                             // else
                   mov  I, 4                         //  I=4;
                 next_2:

              next_C:                             // else

             jmp  next_F
           else_F:


             cmp  eax, dword ptr[edx + 6*4 + 4]// if (N<Dec->DecodeLen[6]) 
             jae  else_E

                cmp  eax, dword ptr[edx + 5*4 + 4]// if (N<Dec->DecodeLen[5]) 
                jae  else_3
                mov  I, 5                         //  I=5;
                jmp  next_3
              else_3:                             // else
                mov  I, 6                         //  I=6;
              next_3:

             jmp  next_E
           else_E:                             // else

                cmp  eax, dword ptr[edx + 7*4 + 4]// if (N<Dec->DecodeLen[7]) 
                jae  else_4
                mov  I, 7                         //  I=7;
                jmp  next_4
              else_4:                             // else
                mov  I, 8                         //  I=8;
              next_4:

           next_E:

           next_F:

          jmp  next_G
        else_G:

          cmp  eax, dword ptr[edx + 12*4 + 4] // if (N<Dec->DecodeLen[12]) 
          jae  else_D

             cmp  eax, dword ptr[edx + 10*4 + 4]// if (N<Dec->DecodeLen[10]) 
             jae  else_B

                cmp  eax, dword ptr[edx + 9*4 + 4]// if (N<Dec->DecodeLen[9])
                jae  else_5
                mov  I, 9                         //  I=9;