win32 DCB structure feature

[FengChendian]

Hello,
I can't find DCB struct in this package. Would it be possible to provide wrappers to DCB interfaces in winbase.h? It's important to implement serial port communication.
Thanks.

[timsneath]

Of course! I've updated the main branch with this and added a number of relevant Win32 APIs.

Please let me know if you need anything else.

[timsneath]

v2.1.2 is published, including these changes: https://pub.dev/packages/win32

[FengChendian]

Thanks for quick updates! Now I can find DCB struct.

But I have a little problem about setting DCB parameters.
In C++, I can

DCB dcbSerialParameters = {0};
if (!GetCommState(this->handler, &dcbSerialParameters))
{
    std::cerr << "Failed to get current serial parameters\n";
} else
{
    dcbSerialParameters.BaudRate = CBR_115200;
}

How can I set dcbSerialParameters in dart? I try

final dcb = DCB();
dcb.BaudRate = 115200;

But I met "Exited (3221225477)"

[timsneath]

You need to do something like:

final dcb = calloc<DCB>();
dcb.ref.BaudRate = 115200;

DCB has to be natively allocated (hence the calloc). The first line returns a Pointer<DCB>, and then you can access the underlying members using the .ref property.

[FengChendian]

Thanks! Now I know how to use native Struct.

BTW, I found when I open "COM5" using dart, the handle always euqal -1. But I can open this port sucessfully with similar C++ code.
Because of GetLastError() #189 problem, I don't know if this is my code bug or package bug. When dart-lang/sdk#38832 fixed, I will track this. Here is my dart code:

final portName = TEXT("COM5");

final handler = CreateFile(portName, GENERIC_ALL, 0, nullptr, OPEN_EXISTING,
    FILE_ATTRIBUTE_NORMAL, NULL);

if (handler == INVALID_HANDLE_VALUE) {
  final lastError = GetLastError();
  if (lastError == ERROR_FILE_NOT_FOUND) {
    print(portName.toDartString() + "is not available");
  } else {
    print('get ${lastError}');
  }
  print("handler error");
  return;
}

[timsneath]

I added an example here:
https://github.com/timsneath/win32/blob/ac9a8bc7febc11f04e57da105b122c3941b23b0c/example/serial.dart

This seems to work successfully on my machine at least:

[C:\src\win32] dart example\serial.dart
BaudRate = 1200, ByteSize = 7, Parity = 2, StopBits = 0
BaudRate = 57600, ByteSize = 8, Parity = 0, StopBits = 0

[FengChendian]

LOL... After compare with the example, I found my code bug. I use GENERIC_ALL instead ofGENERIC_READ | GENERIC_WRITE in dart.
Now it worked! Thank you very much!