unsigned __int8 __fastcall VgaSeqRegReadModifyWrite(unsigned __int16 a1, unsigned __int8 a2, char a3, char a4)
{
  unsigned __int8 v4; // al
  unsigned __int8 result; // al
  unsigned __int16 v6; // [esp+0h] [ebp-8h]

  __outbyte(a1, a2);
  v6 = a1 + 1;
  v4 = __inbyte(a1 + 1);
  result = a4 | a3 & v4;
  __outbyte(v6, result);
  return result;
}