C＃指向非托管结构的数组 [英] C# pointer to unmanaged struct with array

问题描述

这是我要转换的字符串的结构：

  typedef struct 
 {
 UINT8 TrafficClass0：4; 
 UINT8版本：4; 
 UINT8 FlowLabel0：4; 
 UINT8 TrafficClass1：4; 
 UINT16 FlowLabel1; 
 UINT16长度; 
 UINT8 NextHdr; 
 UINT8 HopLimit; 
 UINT32 SrcAddr [4]; 
 UINT32 DstAddr [4]; 
} DIVERT_IPV6HDR，* PDIVERT_IPV6HDR; 
  

这里是我的C＃结构：

  [StructLayoutAttribute（LayoutKind.Sequential）] 
 public struct DivertIPv6Header 
 {
 /// TrafficClass0：4 
 ///版本：4 
 /// FlowLabel0：4 
 /// TrafficClass1：4 
 public uint bitvector1; 
 
 /// UINT16-> unsigned short 
 public ushort FlowLabel1; 
 
 /// UINT16-> unsigned short 
 public ushort长度; 
 
 /// UINT8-> unsigned char 
 public byte NextHdr; 
 
 /// UINT8-> unsigned char 
 public byte HopLimit; 
 
 /// UINT32 [4] 
 [MarshalAsAttribute（UnmanagedType.ByValArray，SizeConst = 4，ArraySubType = UnmanagedType.U4）] 
 public uint [] SrcAddr; 
 
 /// UINT32 [4] 
 [MarshalAsAttribute（UnmanagedType.ByValArray，SizeConst = 4，ArraySubType = UnmanagedType.U4）] 
 public uint [] DstAddr; 
 
 public uint TrafficClass0 
 {
 get 
 {
 return bitvector1& 15岁
} 
 set 
 {
 bitvector1 = value | bitvector1; 
} 
} 
 
 public uint Version 
 {
 get 
 {
 return（bitvector1& 240u）/ 16; 
} 
 set 
 {
 bitvector1 =（value * 16）| bitvector1; 
} 
} 
 
 public uint FlowLabel0 
 {
 get 
 {
 return（bitvector1& 3840u）/ 256; 
} 
 set 
 {
 bitvector1 =（value * 256）| bitvector1; 
} 
} 
 
 public uint TrafficClass1 
 {
 get 
 {
 return（bitvector1& 61440u）/ 4096; 
} 
 set 
 {
 bitvector1 =（value * 4096）| bitvector1; 
} 
} 
} 
  

这里唯一的问题是我需要声明一个指向此结构的指针，以便我可以与它的数据重叠。

如果我尝试声明一个指针，我得到这个编译时错误： p>

 无法声明非非托管类型的指针。 
  

任何想法？

解决方案

使用 Marshal.PtrToStructure ：

  var bytes = yourUnmanagedByteArray; 
 
固定（byte * b = bytes）
 return（T）Marshal.PtrToStructure（new IntPtr（b），typeof（DivertIPv6Header））; 
  

您可以使其无需固定缓冲区，如果你不想使用不安全的代码。

I am trying to implement a C style struct in C# for interoperability.

Here is the struct I'm string to convert:

typedef struct
{
    UINT8  TrafficClass0:4;
    UINT8  Version:4;
    UINT8  FlowLabel0:4;
    UINT8  TrafficClass1:4;
    UINT16 FlowLabel1;
    UINT16 Length;
    UINT8  NextHdr;
    UINT8  HopLimit;
    UINT32 SrcAddr[4];
    UINT32 DstAddr[4];
} DIVERT_IPV6HDR, *PDIVERT_IPV6HDR;

And here is my C# struct:

[StructLayoutAttribute(LayoutKind.Sequential)]
public struct DivertIPv6Header
{
    /// TrafficClass0 : 4
    /// Version : 4
    /// FlowLabel0 : 4
    /// TrafficClass1 : 4
    public uint bitvector1;

    /// UINT16->unsigned short
    public ushort FlowLabel1;

    /// UINT16->unsigned short
    public ushort Length;

    /// UINT8->unsigned char
    public byte NextHdr;

    /// UINT8->unsigned char
    public byte HopLimit;

    /// UINT32[4]
    [MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 4, ArraySubType = UnmanagedType.U4)]
    public uint[] SrcAddr;

    /// UINT32[4]
    [MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 4, ArraySubType = UnmanagedType.U4)]
    public uint[] DstAddr;

    public uint TrafficClass0
    {
        get
        {
            return bitvector1 & 15u;
        }
        set
        {
            bitvector1 = value | bitvector1;
        }
    }

    public uint Version
    {
        get
        {
            return (bitvector1 & 240u) / 16;
        }
        set
        {
            bitvector1 = (value * 16) | bitvector1;
        }
    }

    public uint FlowLabel0
    {
        get
        {
            return (bitvector1 & 3840u) / 256;
        }
        set
        {
            bitvector1 = (value * 256) | bitvector1;
        }
    }

    public uint TrafficClass1
    {
        get
        {
            return (bitvector1 & 61440u) / 4096;
        }
        set
        {
            bitvector1 = (value * 4096) | bitvector1;
        }
    }
}

The only problem here is that I need to declare a pointer to this structure so that I can overlap with it's data.

If I try to declare a pointer I got this compile-time error:

cannot declare pointer to non-unmanaged type.

Any ideas?

解决方案

Use Marshal.PtrToStructure:

        var bytes = yourUnmanagedByteArray;

        fixed (byte* b = bytes)
            return (T)Marshal.PtrToStructure(new IntPtr(b), typeof(DivertIPv6Header));

You could make it work without a fixed buffer too, if you don't want to use unsafe code.

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