从用 C++ 编写的 DLL 调用自定义类型；来自 c#

发布于 2024-08-20 11:06:52 字数 467 浏览 6 评论 0原文

我在我的 C# 项目中使用用 C++ 编写的 DLL。我已经能够使用以下代码调用 DLL 中的函数：

[DllImport("hidfuncs", EntryPoint = "vm_hid_scan", ExactSpelling = true, CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
        public static extern IntPtr VmHidScan();

现在我需要调用一个需要自定义类型指针的函数。 DLL 的文档布局如下：

hid_get_info(int n,PDEV_INFO *pdi)

我不知道如何使用这个自定义指针。这是在DLL中定义的吗？如果是这样，如何从 C# 项目中使用它？如果没有，我需要在 c# 中包含头文件吗？预先感谢您的帮助。

原文

I'm using a DLL written in c++ in my C# project. I have been able to call functions within the DLL using this code:

[DllImport("hidfuncs", EntryPoint = "vm_hid_scan", ExactSpelling = true, CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
        public static extern IntPtr VmHidScan();

Now I need to call a function that requres a custom type pointer. The Docs for the DLL layout the function like this:

hid_get_info(int n,PDEV_INFO *pdi)

I don't know how to use this custom pointer. Is this defined in the DLL? If so how can use it from C# project? If not do I need to include the header file in c#? Thanks in advance for your help.

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南烟 2024-08-27 11:06:52

给定“P”前缀，看起来真正的声明是

hid_get_info(int n, DEV_INFO **pdi)

DEV_INFO 是一个结构。您需要找到此结构的声明，并使用 [StructLayout] 属性将其添加到 C# 代码中。然后，您可以在 C# 代码中声明如下函数：

[DllImport("blah.dll")]
private static extern something hid_get_info(int n, out IntPtr pdi);

并使用 Marshal.PtrToStructure() 获取结构值。希望你不必释放结构，否则你会被搞砸的。

第二种解释是“pid”返回指向 DEV_INFO 结构的指针数组。有点可能给出“n”参数，这很可能意味着您传递给函数填充的数组中的元素数量。在这种情况下，传递 IntPtr[] 并将“n”设置为其长度。

Given the "P" prefix, it looks like the real declaration is

hid_get_info(int n, DEV_INFO **pdi)

where DEV_INFO is a structure. You'll need to find the declaration of this structure and add it to your C# code with the [StructLayout] attribute. You'd then declare the function like this in your C# code:

[DllImport("blah.dll")]
private static extern something hid_get_info(int n, out IntPtr pdi);

and use Marshal.PtrToStructure() to obtain the structure value. Hopefully you don't have to free the structure, you'd be screwed.

A second interpretation is that "pid" returns an array of pointers to DEV_INFO structures. Somewhat likely given the "n" argument, which could well mean the number of elements in the array you pass to be filled by the function. In that case, pass an IntPtr[] and set "n" to its Length.

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踏月而来 2024-08-27 11:06:52

您需要在 C# 中创建一个 struct 来镜像 C++ 中的 C++ PDEV_INFO struct。

您应该将 [StructLayout(LayoutKind.Sequential)] 应用于该结构，然后按顺序从 C++ 结构复制字段（查看头文件）。

然后，您可以编写一个将 struct 作为 ref 参数的 extern 方法。

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悸初 2024-08-27 11:06:52

我可以放心地假设 PDEV_INFO* 是 DEV_INFO**。

在 C# 中使用它：

class DEV_INFO
{
    // fields go here
}

static class NativeMethods
{
    [DllImport...]
    public static extern int hid_get_info(int n, ref DEV_INFO pdi);
}

I'll safely assume PDEV_INFO* is a DEV_INFO**.

Use this in C#:

class DEV_INFO
{
    // fields go here
}

static class NativeMethods
{
    [DllImport...]
    public static extern int hid_get_info(int n, ref DEV_INFO pdi);
}

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