将Delphi变体记录转换为C#

如何将此代码从Delphi转换为C#？我需要struct与unmaneged代码进行交互.

TDataTypeParam = packed record
 dtType : integer;
 case integer of
   cInt     :(dtInt      : integer);
   cFloat   :(dtFloat    : real);
   cLongInt :(dtLongInt  : Int64);
   cDateTime:(dtDateTime : TDateTime);
   cShortStr:(dtShortString : ShortString);
end;

TDataParam =   packed record
 NumberParam : integer;
 Param       : array [1..MaxParam] of TDataTypeParam;
end;

TEvData =   packed record
 dm       : TDateTime;
 CodeEV   : integer;
 IDCAM    : integer;
 Reserv1  : integer;

 Data     : TDataParam;
end;

TArrSrvData =   packed record
 NumberPack : integer;
 Address  : Cardinal;
 tpCL     : integer;
 tpEv     : integer;
 Reserv   : integer;
 Packs      : array [1..MaxPacks] of TEvData;
end;

这段代码抛出System.TypeLoadException：

//TDataTypeParam = packed record
//dtType : integer;//data type
// case integer of
//   cInt     :(dtInt      : integer);
//   cFloat   :(dtFloat    : real);
//   cLongInt :(dtLongInt  : Int64);
//   cDateTime:(dtDateTime : TDateTime);
//   cShortStr:(dtShortString : ShortString);
//end;

[StructLayout(LayoutKind.Explicit)]
[Serializable]
internal struct DataTypeParam
{
    [FieldOffset(0)]
    public DataType dtType;
    [FieldOffset(4)]
    public int dtInt;
    [FieldOffset(4)]
    public double dtFloat;
    [FieldOffset(4)]
    public long dtLongInt;
    [FieldOffset(4)]
    public double dtDateTime;
    [FieldOffset(4)]
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 256)]
    public byte[] dtShortString;
};

//TDataParam =   packed record
//  NumberParam : integer;
//  Param       : array [1..MaxParam] of TDataTypeParam;
// end;
[StructLayout(LayoutKind.Sequential, Pack = 1)]
[Serializable]
internal struct DataParam
{
    public int NumberParam;
    [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.Struct, SizeConst = Consts.MaxParam)]
    public DataTypeParam[] Param;
};

// TEvData =   packed record
//  dm       : TDateTime;
//  CodeEV   : integer;
//  IDCAM    : integer;
//  Reserv1  : integer;

//  Data     : TDataParam;
// end;
[StructLayout(LayoutKind.Sequential, Pack = 1)]
[Serializable]
internal struct EvData
{
    public DateTime dm;
    public int CodeEV;
    public int IDCAM;
    public int Reserv1;
    public DataParam Data;
}

// TArrSrvData =   packed record
//  NumberPack : integer;
//  Address  : Cardinal;
//  tpCL     : integer;
//  tpEv     : integer;
//  Reserv   : integer;
//  Packs      : array [1..MaxPacks] of TEvData;
// end;
// PArrSrvData = ^TArrSrvData;

[StructLayout(LayoutKind.Sequential, Pack = 1)]
[Serializable]
internal struct ArrSrvData
{
    public int NumberPack;
    public uint Address;
    public int tpCL;
    public int tpEv;
    public int Reserv;
    [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.Struct, SizeConst = Consts.MaxPacks)]
    public EvData[] Param;
}

这个问题出在cShortStr：(dtShortString：ShortString);转换…

这是实际代码：

void mySink_NewEvent(ref object Comm)
    {
        byte[] arr = Comm as byte[];
        if(arr == null) return;

        var data = (ArrSrvData)MarshalSerializer.RawDeserialize(arr, typeof(ArrSrvData));

    }

和RawDeserialize代码：

public static object RawDeserialize(byte[] rawData, Type type)
    {
        if (rawData == null)
            throw new ArgumentNullException(MethodBase.GetCurrentMethod().GetParameters()[0].Name);

        int rawsize = Marshal.SizeOf(type);
        if (rawsize > rawData.Length)
            return null;

        object retobj;

        GCHandle handle = GCHandle.Alloc(rawData, GCHandleType.Pinned);
        try
        {
            IntPtr buffer = handle.AddrOfPinnedObject();
            retobj = Marshal.PtrToStructure(buffer, type);
        }
        finally
        {
            handle.Free();
        }

        return retobj;
    }

你有几个问题.

首先,C#DateTime不映射到Delphi TDateTime.您需要在C#代码中使用double,并编写从C#日期/时间到Delphi日期/时间的映射.

第二个问题,更严重的是,确实是字符串.在Delphi中,ShortString是256字节宽.第一个字节包含字符串长度,其余255个是有效负载.

您不能在C#联合中使用非引用类型覆盖引用类型.这是你的问题.除了作为引用类型的字符串之外,所有重叠变量都是值类型. Hans Passant在这里讨论了这个问题：C# Platform-invoke, c-style union with reference and value types.请注意,他明确地提到了您遇到的异常.

在MSDN,您可以找到相同的信息：

In managed code, value types and reference types are not permitted to overlap.

对此问题的正常响应是停止混合引用和值类型.最好只使用blittable值类型.但我没有看到一个明显的方法来做到这一点.您可以使用固定的字节数组,但这会强制您使用不安全的处理固定数组并不是很有趣.可以在此处找到该方法的示例：Marshaling structure with reference-type and value-type members inside a union.

因此,我建议您手动编组记录的变体部分.使用UnmanagedType.ByValArray将其声明为byte [].

[StructLayout(LayoutKind.Sequential)]
[Serializable]
internal struct DataTypeParam
{
    public DataType dtType;
    [MarshalAs(UnmanagedType.ByValArray, SizeConst=256)]
    public byte[] dtUnion;
};

然后你需要编写助手来从/向字节数组读/写单个字段.有了这些助手,你的结构可能看起来像这样：

[StructLayout(LayoutKind.Sequential)]
[Serializable]
internal struct DataTypeParam
{
    public int dtType;
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 256)]
    private byte[] dtUnion;

    public int cInt
    {
        get { return BitConverter.ToInt32(dtUnion, 0); }
        set { dtUnion = BitConverter.GetBytes(value); }
    }

    public double cFloat
    {
        get { return BitConverter.ToDouble(dtUnion, 0); }
        set { dtUnion = BitConverter.GetBytes(value); }
    }
};

我会让你写下剩下的帮手.