从字节数组中读取 C# 中的 C/C++ 数据结构 [英] Reading a C/C++ data structure in C# from a byte array

问题描述

从数据来自 C/C++ 结构的 byte[] 数组填充 C# 结构的最佳方法是什么?C 结构看起来像这样(我的 C 非常生疏):

What would be the best way to fill a C# struct from a byte[] array where the data was from a C/C++ struct? The C struct would look something like this (my C is very rusty):

typedef OldStuff {
    CHAR Name[8];
    UInt32 User;
    CHAR Location[8];
    UInt32 TimeStamp;
    UInt32 Sequence;
    CHAR Tracking[16];
    CHAR Filler[12];
}

并且会填充这样的内容:

And would fill something like this:

[StructLayout(LayoutKind.Explicit, Size = 56, Pack = 1)]
public struct NewStuff
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 8)]
    [FieldOffset(0)]
    public string Name;

    [MarshalAs(UnmanagedType.U4)]
    [FieldOffset(8)]
    public uint User;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 8)]
    [FieldOffset(12)]
    public string Location;

    [MarshalAs(UnmanagedType.U4)]
    [FieldOffset(20)]
    public uint TimeStamp;

    [MarshalAs(UnmanagedType.U4)]
    [FieldOffset(24)]
    public uint Sequence;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
    [FieldOffset(28)]
    public string Tracking;
}

如果将 OldStuff 作为 byte[] 数组传递，将 OldStuff 复制到 NewStuff 的最佳方法是什么?

What is best way to copy OldStuff to NewStuff, if OldStuff was passed as byte[] array?

我目前正在做类似以下的事情，但感觉有点笨拙.

I'm currently doing something like the following, but it feels kind of clunky.

GCHandle handle;
NewStuff MyStuff;

int BufferSize = Marshal.SizeOf(typeof(NewStuff));
byte[] buff = new byte[BufferSize];

Array.Copy(SomeByteArray, 0, buff, 0, BufferSize);

handle = GCHandle.Alloc(buff, GCHandleType.Pinned);

MyStuff = (NewStuff)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(NewStuff));

handle.Free();

有没有更好的方法来实现这一点?

Is there better way to accomplish this?

使用 BinaryReader 类是否会比固定内存和使用 Marshal.PtrStructure 提供任何性能提升?

Would using the BinaryReader class offer any performance gains over pinning the memory and using Marshal.PtrStructure?

推荐答案

从我所看到的上下文来看，您不需要将 SomeByteArray 复制到缓冲区中.您只需要从 SomeByteArray 获取句柄，固定它，使用 PtrToStructure 复制 IntPtr 数据，然后释放.不需要副本.

From what I can see in that context, you don't need to copy SomeByteArray into a buffer. You simply need to get the handle from SomeByteArray, pin it, copy the IntPtr data using PtrToStructure and then release. No need for a copy.

那就是:

NewStuff ByteArrayToNewStuff(byte[] bytes)
{
    GCHandle handle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
    try
    {
        NewStuff stuff = (NewStuff)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(NewStuff));
    }
    finally
    {
        handle.Free();
    }
    return stuff;
}

通用版本:

T ByteArrayToStructure<T>(byte[] bytes) where T: struct 
{
    T stuff;
    GCHandle handle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
    try
    {
        stuff = (T)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(T));
    }
    finally
    {
        handle.Free();
    }
    return stuff;
}

更简单的版本(需要 unsafe 开关):

Simpler version (requires unsafe switch):

unsafe T ByteArrayToStructure<T>(byte[] bytes) where T : struct
{
    fixed (byte* ptr = &bytes[0])
    {
        return (T)Marshal.PtrToStructure((IntPtr)ptr, typeof(T));
    }
}

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