SiGetBootDeviceNameFromRegistry

INT64 __fastcall SiGetBootDeviceNameFromRegistry(PWCHAR KeyName, INT64 a2, INT64 a3, UINT64 *a4){
  NTSTATUS RegistryValue; 
  RegistryValue = SiGetRegistryValue(
                    KeyName,
                    KeyName,
                    (PVOID *)L"\\Registry\\Machine\\SYSTEM\\CurrentControlSet\\Control",
                    a4);
  if( RegistryValue >= 0 )
    return(unsigned int)-1073741823;
  return(unsigned int)RegistryValue;
}

Referenced by:

SiGetBootDeviceName
SiIsWinPeHardDiskZeroUfdBoot