Original decoding function

igned __int64 __fastcall sub_4007BE(__int64 a1, int a2)
{
  signed __int64 result; // rax@2
  char v3; // ST1F_1@4
  char v4; // ST1F_1@4
  unsigned __int8 v5; // ST1F_1@4
  signed int i; // [sp+14h] [bp-10h]@3

  if ( a2 == 16 )
  {
    for ( i = 0; i <= 15; ++i )
    {
      v3 = (*(_BYTE *)(a1
                     + (signed int)(((((unsigned int)((i + 3) >> 31) >> 28) + (_BYTE)i + 3) & 0xF)
                                  - ((unsigned int)((i + 3) >> 31) >> 28))) | *(_BYTE *)(a1
                                                                                       + (signed int)(((((unsigned int)(i >> 31) >> 28) + (_BYTE)i) & 0xF) - ((unsigned int)(i >> 31) >> 28))))
         - (*(_BYTE *)(a1
                     + (signed int)(((((unsigned int)(i >> 31) >> 28) + (_BYTE)i) & 0xF)
                                  - ((unsigned int)(i >> 31) >> 28))) & *(_BYTE *)(a1
                                                                                 + (signed int)(((((unsigned int)((i + 3) >> 31) >> 28)
                                                                                                + (_BYTE)i
                                                                                                + 3) & 0xF)
                                                                                              - ((unsigned int)((i + 3) >> 31) >> 28))));
      v4 = (v3 | *(_BYTE *)(a1
                          + (signed int)(((((unsigned int)((i + 5) >> 31) >> 28) + (_BYTE)i + 5) & 0xF)
                                       - ((unsigned int)((i + 5) >> 31) >> 28))))
         - (v3 & *(_BYTE *)(a1
                          + (signed int)(((((unsigned int)((i + 5) >> 31) >> 28) + (_BYTE)i + 5) & 0xF)
                                       - ((unsigned int)((i + 5) >> 31) >> 28))));
      v5 = (v4 | *(_BYTE *)(a1
                          + (signed int)(((((unsigned int)((i + 11) >> 31) >> 28) + (_BYTE)i + 11) & 0xF)
                                       - ((unsigned int)((i + 11) >> 31) >> 28))))
         - (v4 & *(_BYTE *)(a1
                          + (signed int)(((((unsigned int)((i + 11) >> 31) >> 28) + (_BYTE)i + 11) & 0xF)
                                       - ((unsigned int)((i + 11) >> 31) >> 28))));
      if ( byte_602060[(signed __int64)i] != (v5 | *(_BYTE *)(a1
                                                            + (signed int)(((((unsigned int)((i + 12) >> 31) >> 28)
                                                                           + (_BYTE)i
                                                                           + 12) & 0xF)
                                                                         - ((unsigned int)((i + 12) >> 31) >> 28))))
                                           - (v5 & *(_BYTE *)(a1
                                                            + (signed int)(((((unsigned int)((i + 12) >> 31) >> 28)
                                                                           + (_BYTE)i
                                                                           + 12) & 0xF)
                                                                         - ((unsigned int)((i + 12) >> 31) >> 28)))) )
        return 0LL;
    }
    result = 1LL;
  }
  else
  {
    result = 0LL;
  }
  return result;
}