struct PKGHeader
{
   DWORD dwTableOffset;
};

goto dwTableOffset

struct PKGTableHeader
{
   DWORD dwTableSize;
   DWORD dwTableBlockCount;
};

struct PKGTableBlockEntry
{
   DWORD dwBlockPosition;
   WORD dwBlockTableZSize;
   WORD dwBlockTableSize;
};

File data compressed too and have custom header

struct PKGFileDataHeader
{
   DWORD dwBlockCount;
};

struct PKGFileDataEntry
{
   DWORD dwBlockOffset;
   WORD dwBlockZSize;  //can be 0 , don't know how avoid it
   WORD dwBlockSize;
};

// for Table
struct PKGDataEntry
{
   DWORD dwNameLength;
   String pFileName; // Unicode
   DWORD dwOffset;
   DWORD dwSize;
};

int __cdecl System__Compression__Decompress(unsigned int pScrBuffer, int pScrSize, unsigned int pDstBuffer, int pDstSize)
{
  unsigned int v4; // eax@1
  unsigned int v5; // ebx@1
  unsigned int v6; // edi@1
  unsigned int v7; // edx@2
  int v8; // edx@3
  int v9; // edx@6
  int v10; // esi@6
  unsigned int v11; // esi@6
  int v12; // ecx@8
  int v13; // ecx@10
  int v15; // [sp+14h] [bp+8h]@1
  unsigned int v16; // [sp+1Ch] [bp+10h]@1

  v5 = pDstBuffer;
  v6 = pScrBuffer;
  v16 = pScrBuffer + pScrSize;
  v4 = v5;
  v15 = v5 + pDstSize;
  while ( 1 )
  {
    v7 = *(BYTE *)v6++;
    if ( v7 >= 0x20 )
      break;
    v8 = v7 + 1;
    if ( v8 + v4 > v15 )
      return 0;
    do
    {
      *(BYTE *)v4++ = *(BYTE *)v6++;
      --v8;
    }
    while ( v8 );
LABEL_12:
    if ( v6 >= v16 )
      return v4 - v5;
  }
  v11 = v7;
  v9 = (v7 & 0x1F) << 8;
  v10 = v11 >> 5;
  if ( v10 == 7 )
    v10 = *(BYTE *)v6++ + 7;
  v12 = v4 - v9 - 1 - *(BYTE *)v6++;
  if ( v10 + v4 + 2 <= v15 && v12 >= v5 )
  {
    *(BYTE *)v4 = *(BYTE *)v12;
    *(BYTE *)(v4 + 1) = *(BYTE *)(v12 + 1);
    v4 += 2;
    v13 = v12 + 2;
    do
    {
      *(BYTE *)v4++ = *(BYTE *)v13++;
      --v10;
    }
    while ( v10 );
    goto LABEL_12;
  }
  return 0;
}