int __thiscall PciRegClearBit(int this)
{
  int v2; // ecx
  _DWORD *v3; // edi
  int n15; // ebx
  int v5; // ecx
  char n3; // al
  int n3465; // ebx
  char v8; // al
  unsigned __int16 n4; // ax
  int n510533696; // edx
  int v11; // eax
  int v12; // edx
  int result; // eax
  int v14; // [esp+4h] [ebp-4h] BYREF

  if ( (VgaCrtcRegAnd(0xD0u, 0xFFu) & 0x80u) == 0 )
  {
    v2 = *(_DWORD *)(this + 60);
    if ( *(_BYTE *)(this + 28) < 0x20u )
    {
      v3 = &unk_FFE7776C;
      PciRegWrite(v2, 510525696, 168);
      while ( PciRegRead(*(_DWORD *)(this + 60), 510525696) != 168 )
        ;
    }
    else
    {
      v3 = &unk_FFE7758C;
      PciRegWrite(v2, 510533632, 378054824);
      while ( PciRegRead(*(_DWORD *)(this + 60), 510533632) != 1 )
        ;
      PciRegWrite(*(_DWORD *)(this + 60), 510525440, -60816631);
      while ( PciRegRead(*(_DWORD *)(this + 60), 510525440) != 1 )
        ;
    }
    while ( 1 )
    {
      n4 = *(_WORD *)v3;
      if ( *(_WORD *)v3 == 0xFFFF )
        break;
      if ( n4 == 0xFF00 )
      {
        n15 = 15;
        do
        {
          v5 = v3[1];
          if ( v5 )
            MicroSecondDelay(v5);
          --n15;
        }
        while ( n15 );
      }
      else if ( n4 == 4 && *(_BYTE *)(this + 28) >= 0x20u )
      {
        n3 = *(_BYTE *)(this + 29);
        n3465 = v3[1];
        if ( n3 == 1 )
        {
          n3465 = 3465;
        }
        else if ( n3 == 3 )
        {
          n3465 = 3213;
        }
        v8 = PciRegRead(*(_DWORD *)(this + 60), 510533744);
        PciRegWrite(*(_DWORD *)(this + 60), 510525444, (4 * (v8 & 0xC)) | n3465);
      }
      else
      {
        PciRegWrite(*(_DWORD *)(this + 60), n4 + 510525440, v3[1]);
      }
      v3 += 2;
    }
    if ( PciRegRead(*(_DWORD *)(this + 60), 510525728) == 20577 )
    {
      v14 = *(_DWORD *)(this + 60);
      PciRegRead(v14, 510525444);
      PciRegSetBit(&v14);
    }
    n510533696 = 510533696;
    if ( *(_BYTE *)(this + 28) < 0x10u )
      n510533696 = 510525760;
    v11 = PciRegRead(*(_DWORD *)(this + 60), n510533696);
    PciRegWrite(*(_DWORD *)(this + 60), v12, v11 | 0xC0);
  }
  do
    result = VgaCrtcRegAnd(0xD0u, 0xFFu);
  while ( (result & 0x40) == 0 );
  return result;
}