Von C++ nach Delphi (Union + Struct)

[Robotiker]

Hallo,

hier ist die Doku zu Bitfeldern beim C++ Builder und Visual C++
http://docwiki.embarcadero.com/RADStudio/en/Bit_Fields
http://msdn.microsoft.com/de-de/library/ewwyfdbe.aspx

Man sollte auch schauen, von welchem C++ Compiler der umzusetzende Code kommt, denn in der C++ Builder Doku steht:

Zitat:

According to the C and C++ language specifications, the alignment and storage of bit fields is implementation defined. Therefore, compilers can align and store bit fields differently. If you want complete control over the layout of bit fields, it is advisable to write your own bit field accessing routines and create your own bit fields.

[omata]

Hier mal mein Vorschlag für D7:

Delphi-Quellcode:

type
  TBMRecContent = (bmRecipient, bmReserved, bmType, bmDir);
  TBMRec = record
    data : Byte;
  end;

  _BM_REQUEST_TYPE = packed record
    case Byte of
      0 : (_BM: TBMRec);
      1 : (B: Byte);
  end;

:

implementation

:

function getBMRecContent(BMRecContent:TBMRecContent; BMRec:TBMRec): Byte;
begin
  case BMRecContent of
    bmRecipient: result := (BMRec.data shr 6) and 3;
    bmReserved:  result := (BMRec.data shr 3) and 7;
    bmType:      result := (BMRec.data shr 1) and 3;
    bmDir:       result := (BMRec.data and 1);
  else
    Result:=0;
  end;
end;

procedure TForm.ButtonClick(Sender: TObject);
var BM_REQUEST_TYPE: _BM_REQUEST_TYPE;
begin
  BM_REQUEST_TYPE._BM.data:=3;
  ShowMessage(Format(
    'Recipient = %d, Reserved = %d, Type = %d, Dir = %d',
    [getBMRecContent(bmRecipient, BM_REQUEST_TYPE._BM),
     getBMRecContent(bmReserved, BM_REQUEST_TYPE._BM),
     getBMRecContent(bmType, BM_REQUEST_TYPE._BM),
     getBMRecContent(bmDir, BM_REQUEST_TYPE._BM)]
  ));
end;