delphi - 将C结构转换为delphi

Question

我需要将下面的结构转换为delphi。我对这个“:4”值在“保留”和“版本”成员中意味着什么感到怀疑。看起来它干扰了结构的尺寸!有人有什么建议吗？

typedef struct _FSRTL_COMMON_FCB_HEADER {
  CSHORT        NodeTypeCode;
  CSHORT        NodeByteSize;
  UCHAR         Flags;
  UCHAR         IsFastIoPossible;
  UCHAR         Flags2;
  UCHAR         Reserved  :4;
  UCHAR         Version  :4;
  PERESOURCE    Resource;
  ...

Answer 1

正如评论已经说过的，这是一个位域，即一组共同形成字节、字或双字的位。

最简单的解决方案是:

type
  _FSRTL_COMMON_FCB_HEADER = record
  private
    function GetVersion: Byte;
    procedure SetVersion(Value: Byte);
  public
    NodeTypeCode: Word;
    ...
    ReservedVersion: Byte; // low 4 bits: reserved
                           // top 4 bits: version 
    // all other fields here

    property Version: Byte read GetVersion write SetVersion;
    // Reserved doesn't need an extra property. It is not used.
  end;

  ...

implementation

function _FSRTL_COMMON_FCB_HEADER.GetVersion: Byte;    
begin
  Result := (ReservedVersion and $F0) shr 4;
end;

procedure _FSRTL_COMMON_FCB_HEADER.SetVersion(Value: Byte);
begin
  ReservedVersion := (Value and $0F) shl 4;
end;

一个不太简单(但更通用)的解决方案和解释可以在我的文章中找到:http://rvelthuis.de/articles/articles-convert.html#bitfields ，Uli 已链接到该链接。